Increasing the Mission Capability

of the Attack Submarine Force

The Congress of the United States

Congressional Budget Office
NOTES

Unless otherwise indicated, all years referred to in this report are fiscal years and all costs are in 2002

dollars.

The cover shows (top) the Los Angeles class attack submarine Jefferson City (SSN-759) entering

Apra Harbor in Guam and (bottom) the Trident ballistic missile submarine Michigan (SSBN-727),

which was scheduled for retirement in 2003 but will now be converted into a guided-missle submarine. Photos courtesy of the U.S. Navy.
Preface

Today’s U.S. Navy fleet includes 54 attack submarines (SSNs). In 1999, the Chairman of the

Joint Chiefs of Staff released a study concluding that the Navy would need 68 SSNs by 2015

and 76 by 2025 to carry out critical peacetime missions. In public statements and testimony

to the Congress, Navy officials have endorsed those numbers. However, reaching those force goals

by building more submarines would require a substantial investment, which would compete with

many other demands for defense dollars. Are there alternative ways to operate the currently planned

force of 55 SSNs and four SSGNs (converted Trident ballistic missile submarines) that would meet

those goals without increasing the number of attack submarines?

This Congressional Budget Office (CBO) study—prepared at the request of the Subcommittee

on Seapower of the Senate Committee on Armed Services—examines that question. It looks at the

missions and modernization plans of the SSN fleet and analyzes the budgetary implications both of

maintaining that fleet at 55 and of achieving the force goals in the 1999 study by building additional

submarines. The analysis also evaluates three options to increase the mission capability of the

attack submarine force through changes in such things as operating concepts and basing locations.

Those options would enable a force of 55 SSNs to provide the same number of mission days by

2015 and 2025 that 68 or 76 attack submarines, respectively, would provide under current policies—at substantially lower cost than building more submarines.

Eric J. Labs of CBO’s National Security Division wrote this study under the general supervision of J. Michael Gilmore and R. William Thomas. Raymond Hall of CBO’s Budget Analysis

Division prepared the cost estimates under the general supervision of Jo Ann Vines. Russ Beland

helped review the manuscript for factual accuracy before publication. Barry Anderson, David

Austin, Debbie Clay-Mendez, Arlene Holen, and David Moore of CBO provided thoughtful comments on an earlier draft of the study, as did independent naval analyst Norman Polmar. The author

is especially grateful to numerous officials and analysts at the Department of the Navy who answered many requests for information and thereby improved this analysis. (The assistance of such

external participants implies no responsibility for the final product, which rests solely with CBO.)

Christian Spoor edited the study, and Leah Mazade proofread it. Cindy Cleveland produced

drafts of the manuscript, Kathryn Winstead prepared the study for publication, and Annette Kalicki

prepared the electronic versions for CBO’s Web site.

Dan L. Crippen

Director

March 2002

This publication and others by CBO

are available at the agency’s Web site:

www.cbo.gov

Contents

SUMMARY ix

ONE SUBMARINE REQUIREMENTS AND THEIR

IMPLICATIONS FOR THE NAVY’S BUDGET 1

Setting Force Requirements for Attack Submarines 2

The Composition of the SSN Force 3

Evolving Roles and Missions of Attack Submarines 5

The Resource Implications of Building

a Larger SSN Force 7

Bridging the Gap: Basing Three Attack

Submarines in Guam 10

TWO OPTIONS FOR INCREASING THE MISSION

CAPABILITY OF ATTACK SUBMARINES 15

Option I: Convert Four Trident Submarines to SSGNs 15

Option II: Use More Than One Crew on Some 

Virginia Class Submarines 20

Option III: Base More Attack Submarines in Guam 30

Implications of the Options 32

APPENDIXES

A Determining the Size of the Submarine Force 39

B Estimating the Total Cost per Mission Day

and Cost per Additional Mission Day

Under Various Options 41
vi INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

TABLES

S-1. Average Annual Costs of Different Options for

the Attack Submarine Force xiii

S-2. Cost-Effectiveness of Different Options for

the Attack Submarine Force xiv

S-3. Actual and Equivalent Force Levels in 2015 and 2025

Under Various Options xv

S-4. Relative Costs of Different Ways to Add Mission Days

to the Attack Submarine Force xvii

1. Capabilities of Navy Attack Submarines 3

2. Shortfall in Recent Ship Construction, by Type of Ship 11

3. Average Annual Costs of Different Options for

the Attack Submarine Force 19

4. Cost-Effectiveness of Different Options for

the Attack Submarine Force 20

5. Relative Costs of Different Ways to Add Mission Days

to the Attack Submarine Force 32

6. How CBO’s Estimates of Cost per Additional Mission

Day Would Change Under Alternative Assumptions 33

FIGURES

S-1. Composition of the Attack Submarine Force, by Class,

in 2002 and 2025 x

S-2. Average Annual Production Rate for Attack Submarines xi

S-3. Share of the Navy’s Annual Shipbuilding Budget

Devoted to Attack Submarines xii

S-4. Number of Attack Submarines Through 2030 Under

the Navy’s Plan and the Current Production Rate xii

1. Composition of the Attack Submarine Force, by Class,

in 2002 and 2025 2

2. Total Weapons and VLS Cells in the Attack Submarine

Force in 2002, 2015, and 2025 5
CONTENTS vii

3. Average Annual Production Rate for Attack Submarines 8

4. Share of the Navy’s Annual Shipbuilding Budget

Devoted to Attack Submarines 9

5. Number of Attack Submarines Through 2030 Under

the Navy’s Plan and the Current Production Rate 10

6. Effect on Equivalent Force Levels of Basing Three

Attack Submarines in Guam 12

7. Deployment Cycle for an SSGN Assigned to the

Atlantic Fleet and Based in King’s Bay, Georgia 17

8. Effect on Equivalent Force Levels of Converting Four

Trident Submarines to Perform Conventional Missions 18

9. Current Notional Deployment Cycle for an 

Attack Submarine 22

10. Notional Blue/Gold Deployment Cycle for 

an Attack Submarine 24

11. Effect on Equivalent Force Levels of Using Duel Crews

on Some Virginia Class Submarines 25

12. Notional Deployment Cycle for Two Submarines

Operated by Three Rotating Crews 27

13. Effect on Equivalent Force Levels of Using Multiple

Crews on Some Virginia Class Submarines 28

14. Effect on Equivalent Force Levels of Basing

Eleven Submarines in Guam by 2025 30

15. Equivalent Force Levels Under Various Options,

Assuming a Construction Rate of One Attack

Submarine per Year 34

BOXES

1. Estimating the Service Life of an Attack Submarine 4

2. Possible Future Capabilities of Attack Submarines 7

3. Other Forward-Basing Options for Attack Submarines 31

Summary

I

n 1999, the Chairman of the Joint Chiefs of Staff

(CJCS) released a study concluding that the

United States will need a force of 68 attack submarines (SSNs) by 2015 and a force of 76 by 2025 to

fulfill critical missions during peacetime. The study

added that if the number of attack submarines fell

below 55 in 2015 or 62 in 2025, regional commanders in chief would not be able to respond to crucial

demands without putting other national security

needs at risk. (The study also stated that 55 SSNs

were necessary to meet submarine requirements in

wartime.) The Navy’s military leadership endorsed

the higher numbers in the CJCS study, arguing that

today’s fleet of 54 attack submarines is too small to

perform all of its missions.

One factor driving those force goals is the fact

that under current operating policies, attack submarines spend only about 10 percent of their service life

carrying out required missions. Like other types of

Navy ships, they spend most of their service life conducting training, making port calls, going to and from

theaters of operation, and undergoing maintenance.

Building a larger submarine force would require

the Navy to spend much more on attack submarines

than it does today. Alternatively, the Navy could

take various steps to get more mission days from its

current force for less than the cost of building additional submarines. This Congressional Budget Office

(CBO) study looks at three such options, which expand on ideas or practices that the Navy intends to

pursue or that have been mentioned in policy debates.

Those options are:

• Retaining four Trident ballistic missile submarines that are set to be retired and converting

them to perform conventional rather than nuclear missions,

• Using two alternating crews (dual crewing) or

three crews rotating between two submarines

(multiple crewing) to operate some attack submarines more efficiently, and

• Basing more submarines in the Pacific island of

Guam rather than in the United States.

Converting four Trident submarines to perform

conventional missions cited in the CJCS study (using

a so-called SSGN configuration) would provide a

cost-effective way to increase the mission capability

of the attack submarine force until those subs were

retired by the mid-2020s.1

 After that, basing 11 submarines in Guam or using dual or multiple crews for

some attack submarines would enable a force of 55

SSNs to provide the same number of mission days as

a 76-submarine force operating under today’s policies. (Of course, the Navy would not have to wait

until the mid-2020s to make those two changes.)

Overall, basing submarines in Guam represents the

most cost-effective option of the three that CBO examined.

1. In the Navy’s designations, SSN refers to a nuclear-powered attack

submarine and SSGN to a nuclear-powered guided-missile submarine. Trident subs are SSBNs, nuclear-powered ballistic missile

submarines.
x INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

2002

Seawolf

(2)

Other

(1)

Improved

Los Angeles

(23) Los Angeles

with VLS

(8)

Pre-VLS

Los Angeles

(20)

2025

Seawolf

(3)

Improved

Los Angeles

(12)

Virginia and

Successor

(42)

To keep its analysis impartial, CBO used assumptions and methods to evaluate cost-effectiveness

that did not favor either submarine construction or

the alternatives to it. On average, CBO estimated

that the Navy’s new Virginia class submarines would

cost about $2.1 billion to produce and that an SSGN

would cost the same amount to operate per year as a

Trident ballistic missile submarine. CBO estimated

that a dual- or multiple-crewed attack submarine

would have higher operating costs than a singlecrewed attack submarine would, though not as high

as those of an SSGN or a ballistic missile submarine

(both of which are dual crewed, have larger crews

than an attack submarine’s, follow a more stringent

and costly maintenance program, and are used more

intensively than a dual- or multiple-crewed SSN

would be in this analysis).

In addition, because the attack submarines with

dual or multiple crews and those based in Guam are

assumed to operate more intensively than singlecrewed attack submarines do, they would have a

shorter service life. That shorter life is incorporated

into CBO’s analysis of cost-effectiveness.

The Attack Submarine Force

and Its Missions

Today’s SSN force consists of 51 Los Angeles class

submarines, two new Seawolf class submarines, and

one submarine equipped to perform special operations and high-value intelligence missions. The Navy

is also developing and beginning to build Virginia

class submarines. Under the Navy’s long-term shipbuilding plan, by 2025 the SSN force will comprise

42 Virginia class submarines and their successors,

three Seawolf class submarines, and 12 Los Angeles

class submarines (see Summary Figure 1).

Although the Virginia will be technologically

more sophisticated than the Los Angeles and thus

may be able to conduct SSN missions more effec

tively, it will not necessarily perform those missions

more efficiently. Thus, the introduction of a new

class of submarine may not reduce the number of

submarines required. In fact, new capabilities could

lead to new missions and thus to greater requirements.

Summary Figure 1.

Composition of the Attack Submarine Force, by Class, in 2002 and 2025 (By number of submarines)

SOURCE: Congressional Budget Office based on data from the Navy.

NOTE: VLS = vertical launch system.
SUMMARY xi

1990s 2002 To Maintain To Field To Field

0

1

2

3

4

Submarines per Year

(Actual) (Planned) 55 SSNs 68 SSNs

by 2015

76 SSNs

by 2025

Traditionally, the missions of attack submarines

included performing covert intelligence gathering,

surveillance, and reconnaissance; conducting covert

special operations; attacking targets on land with

Tomahawk missiles; and engaging in mine warfare,

antisubmarine warfare, and anti-surface-ship warfare.

Those missions are still part of the SSN repertoire,

although in recent years the focus on antisubmarine

warfare has declined and the emphasis on intelligence gathering has grown. The CJCS study expects

that the need for intelligence missions will continue

to increase substantially.

The Resource Implications of

Building a Larger SSN Force

Fielding a force of 68 attack submarines in 2015 and

76 in 2025 would necessitate a higher construction

rate than is now planned or funded. The Navy currently intends to buy six attack submarines between

2002 and 2007, an average of one per year—twice

the production rate of the 1990s (see Summary Figure 2). To meet the 2015 goal, the service would

have to build 24 submarines between 2002 and 2009,

an average of three per year. (Typically, six years

elapse between an attack submarine’s authorization

by the Congress and its commissioning in the Navy.)

To meet the 2025 goal, the Navy would need to order

58 submarines between 2002 and 2019, an average of

3.2 per year.

Reaching and sustaining the 2025 force goal

would require the Navy to spend an average of $6.1

billion per year on submarine construction between

2002 and 2025, CBO estimates. That level of funding represents about 58 percent of the average annual

shipbuilding budget for the next five years envisioned

in the 2003 Future Years Defense Program (FYDP).

By comparison, the Navy devoted 14 percent of its

shipbuilding budget to attack submarines in the 1990s

and 24 percent in 2002 (see Summary Figure 3).

If the Navy indefinitely extended the currently

planned production rate of one submarine per year, it

could sustain the minimum CJCS force level of 55

Summary Figure 2.

Average Annual Production Rate

for Attack Submarines

SOURCE: Congressional Budget Office.

NOTE: SSN = nuclear-powered attack submarine.

SSNs through 2015.2 After that, however, the force

would decline rapidly (see Summary Figure 4). It

would shrink to 36 attack submarines by 2025 and 28

by 2030 as many Los Angeles class submarines

(which were built at rates of three or four a year during the 1970s and 1980s) reached the end of their service life. The Navy’s long-term building plan envisions constructing an average of 2.2 submarines per

year until 2020, which would maintain the SSN force

at about 55 through 2030. That plan would cost an

average of $4.5 billion per year for procurement between 2002 and 2025, CBO estimates—or about 43

percent of the average shipbuilding budget in the

2003 FYDP.3

2. That statement assumes that all of the current Los Angeles class

submarines remain in the fleet for the duration of their service life

(30 to 33 years).

3. As proposed by the President in February, the 2003 FYDP includes

the conversion of all four retiring Trident submarines to SSGNs.

For the purposes of this analysis, however, the Navy’s long-term

plan is not assumed to include those SSGN conversions.
xii INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

1990s 2002 To Maintain To Field To Field

0

10

20

30

40

50

60

70

Percent

(Actual) (Planned) 55 SSNs 68 SSNs

by 2015

76 SSNs

by 2025

2000 2005 2010 2015 2020 2025 2030

0

10

20

30

40

50

60

70

80

90

100

Number of Attack Submarines

Navy's Long-Term Procurement Plan

Current

Production Rate

The gap between the Navy’s long-term procurement plan and its current funding and construction

levels is especially important because attack submarines represent the largest shortfall in the Navy’s

shipbuilding account. By the end of the year, the

Navy expects to have devoted 22 percent of its ship

construction budget between 1998 and 2002 to SSNs,

or an average of $1.9 billion out of $8.8 billion annually. If those numbers were held constant (a steady

state), the Navy could buy 30 attack submarines at an

average price of $2.1 billion apiece (using CBO’s

estimate)—well below the minimum force goal of 55.

In dollar terms, that shortfall amounts to about $1.6

billion a year. Although other shipbuilding programs

face similar problems, their shortfalls are not nearly

as great as the one for SSNs.

To boost the number of mission days provided

by the current SSN force, the Navy has decided to

base three attack submarines in Guam by the end of

Summary Figure 3.

Share of the Navy’s Annual Shipbuilding

Budget Devoted to Attack Submarines

SOURCE: Congressional Budget Office.

NOTES: This figure assumes a future shipbuilding budget of

$10.5 billion per year (adjusted for inflation)—the average under the 2003 Future Years Defense Program.

SSN = nuclear-powered attack submarine.

Summary Figure 4.

Number of Attack Submarines Through 2030

Under the Navy’s Plan and the Current

Production Rate

SOURCE: Congressional Budget Office.

NOTES: The Navy’s long-term plan assumes an average production rate of 2.2 subs a year between 2002 and 2020,

compared with the current rate of one per year. After

2020, it assumes a production rate sufficient to maintain

a force of 55 attack submarines.

Dashed lines identify the force goals of 55, 68, and 76

submarines.

2003. The Navy’s operating concept for Guam-based

submarines would allow them to provide 88 to 123

mission days per year, as opposed to 36 mission days

per year for U.S.-based subs. 

The reason for the difference is that whereas an

SSN based in the United States goes on a six-month

deployment every two years, one based in Guam will

spend a total of six months at sea each year (although

every deployment will last no more than 56 days).

That operating tempo complies with the Navy’s policies about how much time a submarine’s crew may

spend away from its home port—policies that the

Navy considers crucial to recruit and retain personnel. On the basis of the different operating concept

and the fact that Guam is closer than the United

States to likely theaters of operation, CBO calculated

that an attack submarine in Guam would provide an

average of 106 mission days per year (with the rest of

its time at sea spent on other tasks, such as training).
SUMMARY xiii

The Navy’s decision to base three submarines in

Guam has the effect of reducing the number of SSNs

needed to meet the CJCS requirements. With respect

to mission days, a force of 62 attack submarines, assuming that three are stationed in Guam, is equivalent

to 68 U.S.-based SSNs operated under current policies. Similarly, a force of 70 submarines with three

based in Guam is equivalent to 76 SSNs. Stationing

three subs in Guam and building those smaller forces

would cost about $600 million less each year through

2025 in procurement and operating costs than building the full force of 68 or 76 submarines (see Summary Table 1). Moreover, it would lower the cost per

mission day of the SSN force from $2.7 million to

about $2.5 million (see Summary Table 2).

Options for Increasing the

Mission Capability of 

the SSN Force

The Navy could take several other steps to use attack

submarines more efficiently and further increase the

number of mission days provided by the SSN force.

Summary Table 1.

Average Annual Costs of Different Options for the Attack Submarine Force (In millions of dollars)

Procurement

Costs

Operation and

Support Costs

Other

Costsa

Total

Costs

Average Annual Costs Through 2007

Navy’s Current Planb 2,870 1,840 0 4,710

Costs in Addition to the Navy’s Current Plan

Build 68 SSNs by 2015 3,500 0 0 3,500

Build 68 SSN equivalents by 2015c 1,540 0 0 1,540

Build 76 SSNs by 2025 2,510 0 0 2,510

Build 76 SSN equivalents by 2025c 1,440 0 0 1,440

Option I: Convert four Trident subs to SSGNs 550 60 0 610

Option IIA: Use dual crews on some SSNs 0 0 0 0

Option IIB: Use three crews to operate two SSNs 0 0 0 0

Option III: Base more SSNs in Guam 0 0 0 0

Average Annual Costs Through 2025

Navy’s Current Planb 4,480 1,870 0 6,350

Costs in Addition to the Navy’s Current Plan

Build 68 SSNs by 2015 880 260 20 1,160

Build 68 SSN equivalents by 2015c 530 140 10 680

Build 76 SSNs by 2025 1,640 230 30 1,900

Build 76 SSN equivalents by 2025c 1,130 170 20 1,320

Option I: Convert four Trident subs to SSGNs 170 190 10 370

Option IIA: Use dual crews on some SSNs 0 110 20 130

Option IIB: Use three crews to operate two SSNs 0 60 10 70

Option III: Base more SSNs in Guam 0 10 10 20

SOURCE: Congressional Budget Office.

NOTE: SSN = nuclear-powered attack submarine; SSGN = nuclear-powered guided-missile submarine.

a. These costs, which include such things as infrastructure improvements, would occur between 2008 and about 2015.

b. Does not include the cost of converting four Trident submarines to SSGNs.

c. This alternative includes the basing of three submarines in Guam, which reduces the total number of attack submarines required under the

Chairman of the Joint Chiefs of Staff’s submarine study to 62 by 2015 and 70 by 2025.
xiv INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

Summary Table 2.

Cost-Effectiveness of Different Options for the

Attack Submarine Force (In millions of dollars)

Total Cost per

Mission Day

Provided by

the SSN Force

Navy’s Current Plan 2.5

Build 68 SSNs by 2015 2.7

Build 68 SSN Equivalents by 2015a 2.5

Build 76 SSNs by 2025 2.7

Build 76 SSN Equivalents by 2025a 2.5

Option I: Convert Four Trident Subs

to SSGNs 2.2

Option IIA: Use Dual Crews

on Some SSNs 2.2

Option IIB: Use Three Crews

to Operate Two SSNs 2.2

Option III: Base More SSNs in Guam 2.0

SOURCE: Congressional Budget Office.

NOTES: Cost per mission day is calculated using steady-state

estimates of procurement and operation and support

costs. Other costs, such as changes in infrastructure,

are also included.

SSN = nuclear-powered attack submarine; SSGN =

nuclear-powered guided-missile submarine.

a. This alternative includes the basing of three submarines in

Guam, which reduces the total number of attack submarines

required under the Chairman of the Joint Chiefs of Staff’s submarine study to 62 by 2015 and 70 by 2025.

For example, it could convert Trident ballistic missile

submarines to perform missions specified in the

CJCS study, use more than one crew per submarine,

or base more than three SSNs in Guam. CBO compared the mission days that each of those options

could provide with the force goals of the CJCS study.

To show the results in graphic form, CBO converted

the mission-day analysis to equivalent force levels.

In other words, if an attack submarine could provide

an average of 72 mission days per year by adopting a

more efficient crewing concept, it was counted as

two submarines. CBO also compared the cost of the

options with the cost of achieving the same capability

by building new submarines. (Each of the options

assumes that the Navy will base three attack submarines in Guam indefinitely.)

Option I: Convert Four

Trident Submarines to Perform

Conventional Missions

In this alternative, the Navy would maintain 55 attack

submarines and convert four Trident ballistic missile

submarines to perform nonnuclear missions—changing them to an SSGN configuration. With the Cold

War over and the United States planning to reduce its

arsenal of strategic nuclear warheads, the Navy intends to decrease the Trident fleet from 18 submarines to 14, retiring two subs in 2003 and two in

2004. If, instead, their nuclear reactors were refueled, those submarines would have about 20 years

of useful service life left. In this option, the SSGNs

would retain the dual-crew system that Trident submarines use now.

Most of the past discussion about turning Trident submarines into SSGNs has focused on having

them available to perform land-attack or specialoperations missions. Land attack, however, was not

mentioned in the CJCS study as one of the required

missions of attack submarines. For purposes of this

analysis, CBO assumed that the SSGNs would be

used as much as practicable to perform missions

identified in the CJCS study. Whether or not they

should be used that way is an important policy decision.

In any event, SSGNs would not be equipped to

carry out all of the missions of attack submarines.

On the basis of information provided by the Navy,

CBO calculated that SSGNs could perform 17 percent of the mission days identified in the CJCS study.

Thus, although each SSGN could provide a raw average of 142 mission days per year (assuming some of

that time was not needed for at-sea training and certifications), the four SSGNs would be equivalent to

about 12 attack submarines with respect to the total

number of mission days identified in the CJCS
SUMMARY xv

Summary Table 3.

Actual and Equivalent Force Levels in 2015 and 2025 Under Various Options

2015 2025

Actual

Force Levela

Equivalent

Force Level

Actual

Force Levela

Equivalent

Force Level

Option I: Convert Four Trident Subs

to SSGNs 63 76 58 66

Option IIA: Use Dual Crews

on Some SSNs 59 72 57 78

Option IIB: Use Three Crews

to Operate Two SSNs 59 73 57 78

Option III: Base More SSNs in Guam 59 73 57 79

Memorandum:

Force Goal in 1999 CJCS Study n.a. 68 n.a. 76

SOURCE: Congressional Budget Office.

NOTE: SSGN = nuclear-powered guided-missile submarine; SSN = nuclear-powered attack submarine; CJCS = Chairman of the Joint Chiefs

of Staff; n.a. = not applicable.

a. The actual number of submarines tends to vary from year to year according to retirement and commissioning schedules. As it happens,

2015 is one of the peak years for attack submarines under the Navy’s current plan.

study.4 In terms of equivalent force levels, the currently planned force of attack submarines (including

the three in Guam), augmented by four SSGNs,

would achieve even the 76-SSN force goal in 2015.

However, by 2025, it would fall well below that goal

(see Summary Table 3).

Option I would have relatively high costs in the

near term but would be more cost-effective over the

longer term. To refuel, convert, and arm four SSGNs

would cost a total of $4 billion. For the next six

years, costs to convert and operate the subs would

average $610 million per year more than the Navy’s

plan. Over the 2002-2025 period, Option I would

cost an average of $370 million more per year than

the Navy’s plan, but it would reduce the SSN fleet’s

cost per mission day from $2.7 million to $2.2 million. (Option I is the only alternative examined by

CBO that would involve significant start-up costs.)

Option II: Use Dual- or MultipleCrewed Submarines

Another approach would be for the Navy to maintain

55 attack submarines but operate some of them using

either two alternating crews (as it does with Trident

submarines) or three crews rotating between two submarines. In either case, the 55-SSN force would provide the same number of missions days as would a

larger force built to meet the CJCS goals, but much

more cost-effectively.

Option IIA: Adapt the Trident Blue/Gold Crewing Model to SSNs. Under this variant, the Navy

would use a dual-crew operating concept for its new

Virginia class submarines, beginning with the one

4. To provide the exact number of mission days SSGNs could perform

and, therefore, how that calculation was made would reveal information that is currently classified. 

If four SSGNs were equivalent to 12 attack submarines with respect

to the total number of mission days identified in the CJCS study,

each SSGN would have a little more than 35 days a year, on average, to perform other missions or to conduct at-sea training.
xvi INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

due to be authorized in 2003 and commissioned in

2009. By 2015, nine Virginia class submarines

would have dual crews, and by 2025, 19 would have

them. A dual-crewed submarine, as envisioned in

this option, would spend an average of 65 days per

year conducting missions—80 percent more than an

SSN today. As a result, the Navy could perform the

same number of mission days provided by a 68-submarine force using 55 SSNs.

This option would cost an average of $130 million more per year than the Navy’s current plan

through 2025, mostly to pay for the additional crews.

However, the total cost per mission day of the SSN

fleet would decline to $2.2 million.

The Navy has raised several concerns about using dual crews on attack submarines. Those concerns

focus on maintaining the submarines, developing the

new crews, and keeping the crews proficient between

deployments. Navy officials point out that ballistic

missile submarines, which use dual crews, are very

different from Los Angeles class attack submarines,

which do not. Specifically, some of the physical features of today’s ballistic missile submarines were designed with a dual-crew concept in mind. 

In addition, the two types of submarines have

distinct operating cycles. Tridents deploy for two

and one-half months and then return to port for a

short, intensive maintenance period lasting a little

more than a month. That cycle repeats for many

years, with each crew alternating the deployment. In

contrast, attack submarines and their crews spend

about 18 months resting, training, and maintaining

equipment, followed by a six-month deployment. As

a result of those cycles, the maintenance and training

procedures for ballistic missile and attack submarines

are quite different and cannot be easily substituted

for one another.

This option was designed to address the Navy’s

concerns. Rather than adopt the concept used by ballistic missile submarines, it would compress the

planned operating cycle of the new Virginia class

attack submarine using two crews. Both crews would

assist in maintaining the submarine before its deployment. The operating schedule in this option would

allow about the same ratio of maintenance time to atsea time that today’s SSNs have. Moreover, the first

dual-crewed Virginia would not be commissioned

until 2009, giving the Navy time to develop the new

crews. 

In terms of training, this option envisions an

expanded shore-based training infrastructure, as well

as opportunities for both crews to train at sea before a

submarine goes on deployment. The crew deploying

with the sub would receive its normal at-sea training

before departure. During that period, the other crew

would also be able to spend some time at sea so that

it was not completely dependent on shore-based

training to maintain its skills between deployments.

Option IIB: Use Three Crews to Operate Two

Submarines. This alternative would operate two

Virginia class SSNs with three crews, which would

rotate every 90 days to a submarine on a nine-month

deployment. Under this concept, eight Virginia class

submarines would operate with multiple crews by

2015 and 14 by 2025. Those submarines would

spend an average of 73 days per year conducting missions over the course of their service life—double

what SSNs perform today.

This option would meet the CJCS force goals in

2015 and 2025 with the same number of submarines

that the Navy hopes to buy under its current plan.

The annual cost would be $70 million more than the

Navy’s plan through 2025, but the total cost per mission day of this force would be $300,000 lower ($2.2

million).

The principal disadvantage of this option is that

it would represent a radical departure from the way

the Navy operates attack (or ballistic missile) submarines today. Each relief crew would be flown out to a

forward location to take over from the crew operating

a submarine, rather than waiting for the submarine to

return to its home port. The Navy has not used that

technique with attack submarines, although it did so

with some ballistic missile submarines during the

Cold War. 

This alternative would pose other challenges as

well. To make sure the two SSNs that three crews

shared were as similar as possible, the Navy might

need to design and build attack submarines in pairs.

In addition, this option would keep attack submarines

at sea three months longer than SSNs are now, which

could make it harder to keep them in working order.
SUMMARY xvii

Option III: Base More Attack

Submarines in Guam

Under this option, the Navy would permanently base

four more SSNs in Guam by 2015 and eight more by

2025 (besides the three that it already plans to station

there by the end of 2003). Because those submarines

would use a different operating concept and spend

less time in transit than ones based in the United

States, having additional submarines in Guam would

allow a force of 55 SSNs to provide the same number

of mission days as at least 68 subs in 2015 and 76 in

2025.

The principal disadvantage of this option is that

it would require substantially greater infrastructure in

Guam, at a total cost of about $200 million, CBO

estimates. Overall, however, the SSN fleet’s cost per

mission day would fall to $2.0 million—the lowest

cost of all the options that CBO examined.

Force Levels If the Production Rate

Does Not Increase

The options analyzed in this study assume that the

Navy will implement its long-term procurement plan

to keep the attack submarine force at 55. At the same

time, this analysis shows that carrying out that plan

could be difficult because of its cost. 

If the production rate remains at the current

level of one submarine per year, for how long could

the approaches represented in these options maintain

an SSN force equivalent to 55? Option I would sustain that level until 2023. However, because of the

six-year interval between authorizing a submarine

and fielding it, the production rate would need to increase to two or more SSNs per year in 2017. Under

Options IIA and IIB, that rate would have to increase

in 2013 or 2021, respectively, to maintain a force

equivalent to 55 SSNs—assuming that all new Virginia class submarines after the fourth ship were dual

or multiple crewed rather than the smaller numbers

envisioned in the options. Finally, if the Navy put as

many as 12 SSNs in Guam—probably the largest

number it might reasonably want to base there—the

production rate would not have to rise until 2022.

Under all of those scenarios, however, the SSN force

would fall below 55 actual submarines (as opposed to

their equivalent in mission days), which is the wartime requirement stated in the CJCS study.

Overall Cost-Effectiveness

of the Options

All of the options examined by CBO would exceed

the CJCS study’s force goal in 2015 with respect to

equivalent force levels and mission days provided

(see Summary Table 3). In 2025, Options IIA, IIB,

and III would exceed the study’s goal for that year.

Option I would not, however, largely because three of

the four SSGNs would have been retired by then.

Those alternatives would meet the force goals at

a much lower incremental cost than buying new submarines would. (A discussion of how CBO made

that calculation is contained in Appendix B.) Transferring a submarine to Guam would cost $0.2 million

for each additional mission day it provided, making it

the most cost-effective of the options (see Summary

Table 4). Converting a Trident into an SSGN or using more than one crew to operate a Virginia class

Summary Table 4.

Relative Costs of Different Ways to Add

Mission Days to the Attack Submarine Force

(In millions of dollars)

Cost per

Additional

Mission Day

Provided

Build a New Submarine 2.7

Convert a Trident Sub to an SSGN 0.8

Operate an SSN with Two Crews 1.2

Operate an SSN with Three Crews

per Two Subs 0.9

Transfer an SSN to Guam 0.2

SOURCE: Congressional Budget Office.

NOTE: SSGN = nuclear-powered guided-missile submarine; SSN

= nuclear-powered attack submarine.
xviii INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

attack submarine would cost between $0.8 million

and $1.2 million per additional mission day. In comparison, a new submarine would cost an estimated

$2.7 million for each mission day it added to the SSN

force.

The relative cost-effectiveness of those options

is not particularly sensitive to changes in assumptions

about operating or procurement costs. If a dual- or

multiple-crewed attack submarine cost as much to

operate as an SSGN or a Trident ballistic missile submarine (a reasonable upper limit) or even twice as

much as a single-crewed submarine, Options IIA and

IIB would still be more cost-effective than building

submarines with respect to the additional mission

days provided. Further, if costs for procuring new

submarines were lower than what CBO assumed, the

relative cost-effectiveness of the options would be

almost unchanged. (If procurement costs were substantially higher than CBO’s estimate, the cost per

additional mission day of submarine construction

would worsen relative to that of the alternatives.)

Thus, to the extent that the costs both of operating

attack submarines and of producing them are uncertain, all four options are still much more cost-effective than building additional submarines would be.
Chapter One

Submarine Requirements and Their

Implications for the Navy’s Budget

I

n recent years, the Navy has been looking to increase its fleet of attack submarines (SSNs) in

keeping with a 1999 study conducted for the

Chairman of the Joint Chiefs of Staff (CJCS).1

 That

study concluded that the Navy would need 68 attack

submarines by 2015—of which 18 should be from the

new Virginia class—and 76 attack submarines by

2025 to meet the most critical peacetime requirements of the regional commanders in chief as well as

requirements set by the national intelligence community. The study also concluded that 55 SSNs were

necessary to meet potential requirements in wartime.

Those force goals are driven in part by the fact

that under current policies, attack submarines spend

an average of 36 days per year—or 10 percent of

their service life—on-station performing missions

identified as critical or high priority by the President,

the Secretary of Defense, and the regional commanders in chief. Like other Navy ships, SSNs spend the

rest of their service life in training missions, port

calls, transit, and maintenance.

In this study, the Congressional Budget Office

(CBO) looks at the composition of the SSN force today and its expected composition in 2025 under the

Navy’s long-term procurement plan. The study estimates the resources needed either to build more submarines to meet the CJCS force goals or simply to

maintain a force of 55 attack submarines.

Because building a larger force would require

much greater resources than the Navy expects to be

able to devote to submarine construction over the

next 20 years, this study also examines several options for providing additional mission days by using

existing SSNs more cost-effectively. Those options

involve keeping Trident ballistic missile submarines

that would otherwise be retired and converting them

to a guided-missile (SSGN) configuration so they

could perform nonnuclear missions; using dual crews

(two per sub) or multiple crews (in this study, three

crews for two subs) to operate some SSNs more efficiently; and basing more attack submarines in the

Pacific island of Guam. Each of those options would

be more cost-effective than building additional submarines, CBO estimates.

In analyzing the cost-effectiveness of the options, CBO generally used cautious assumptions and

methods to estimate such things as the expected cost

of new Virginia class submarines or of SSGN conversions. Specifically, it assumed that Virginia class

submarines would cost about $2.1 billion to produce,

on average, and that the annual operating costs for an

SSGN would be the same as for a Trident ballistic

missile submarine. Operating costs for a dual- or

multiple-crewed attack submarine would be greater

than for a single-crewed attack submarine, CBO estimated, but not as high as for an SSGN or ballistic

missile submarine (both of which employ a dual-crew

system and have larger crews, a more stringent and

costly maintenance program, and a more intensive

operating tempo than a dual- or multiple-crewed attack submarine would have in this analysis). 

1. Department of Defense, Office of the Joint Chiefs of Staff, CJCS

Attack Submarine Study (November 1999). That study is classified

as secret.
2 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

2002

Seawolf

(2)

Other

(1)

Improved

Los Angeles

(23) Los Angeles

with VLS

(8)

Pre-VLS

Los Angeles

(20)

2025

Seawolf

(3)

Improved

Los Angeles

(12)

Virginia and

Successor

(42)

Further, because this study’s dual- or multiplecrewed attack submarines and submarines based in

Guam would be used more intensively than current

single-crewed SSNs are, they would have a much

shorter service life. CBO’s cost-effectiveness analysis takes that shorter life into account.

Setting Force Requirements

for Attack Submarines

To estimate the necessary force level for SSNs, the

CJCS study used a methodology based on required

mission days. The Joint Staff asked regional military

commanders in chief (CINCs) to identify the missions that attack submarines would perform in their

respective regions in both 2015 and 2025. To generate their estimates, the CINCs used an analysis of the

future global situation and threat environment by

U.S. intelligence agencies. They also ranked each

SSN mission by order of importance. The Joint Staff

then totaled the number of days needed for those missions.

The Joint Staff combined those regional estimates of submarine needs with anticipated national

requirements. For purposes of the CJCS study, they

assumed that all of the critical and most of the highpriority missions would be performed. The desired

size of the SSN force was established using a formula

derived from historical experience that converts the

total number of mission days needed into the total

number of submarines needed (see Appendix A).

For this analysis, CBO retained the mission-day

focus of the CJCS study. Specifically, CBO compared the number of mission days that alternative

submarine force structures would provide. If, for

example, one way of operating a submarine would

provide twice the number of mission days per year,

on average, as operating a submarine under current

practices, that submarine would be considered equivFigure 1.

Composition of the Attack Submarine Force, by Class, in 2002 and 2025 (By number of submarines)

SOURCE: Congressional Budget Office based on data from the Navy.

NOTE: VLS = vertical launch system.
CHAPTER ONE SUBMARINE REQUIREMENTS AND THEIR IMPLICATIONS FOR THE NAVY’S BUDGET 3

alent to two submarines today (taking into account

any reduction in its expected service life).

The Composition of 

the SSN Force

The Navy’s current force of attack submarines comprises two new Seawolf (SSN-21) class submarines,

51 Los Angeles class (SSN-688) submarines, and one

specially equipped submarine for high-value intelligence missions (see Figure 1).

The two Seawolfs are among the quietest and

most capable nuclear-powered attack submarines in

the world. They can launch Tomahawk missiles from

their torpedo tubes, and their overall complement of

weapons is greater than those of Los Angeles class

submarines or the first boats of the new Virginia

class (see Table 1).

The Los Angeles class forms the backbone of

the current attack submarine force. That class, however, consists of three similar but distinct groups of

submarines.

• The earliest group does not have vertical launch

system (VLS) cells for launching Tomahawk

missiles. It also lacks under-ice and minelaying

capabilities, which are considered vital for modern submarine warfare. The Navy has 20 of

those early submarines in the fleet today.

• The second group consists of eight Los Angeles

class submarines that lack under-ice and minelaying capabilities but that are equipped with 12

VLS cells apiece.

• The third group is composed of 23 submarines,

called the Improved Los Angeles class, or

688Is. Submarines in that group possess 12

VLS cells as well as the under-ice and mineTable 1.

Capabilities of Navy Attack Submarines

Los Angeles

Class (Improved)

Seawolf

Class

Virginia

Class 

Size

Displacement (Tons, submerged) 6,900 9,100 7,800

Length (Feet) 360 353 377

Draft (Feet) 32 35 31

Beam (Feet) 33 40 34

Speed (Knots)

Maximum More than 25 More than 25 More than 25

Tactical (Silent speed) n.a. 20 n.a.

Operating Depth (Feet) More than 800 About 1,600 More than 800

Crew Size 129 133 113

Armament (Number of missiles or torpedoes) 37 50 38

Weapon Launchers

Torpedo tubes (21 inches)a 48 4

Vertical launch system cells 12 0 12

SOURCE: Congressional Budget Office.

NOTE: n.a. = not available.

a. The Seawolf has 26.5-inch torpedo tubes that launch its weapons.
4 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

laying capabilities missing in earlier groups.

They also have much quieter machinery than

other submarines of their class.

The sub used for special missions is the Parche,

a Sturgeon class attack submarine that has operated

in that role since 1976. The Navy specially fitted that

boat with equipment for ocean-engineering missions

(such as recovery of satellites and other equipment

from the ocean floor) as well as highly specialized

intelligence-gathering gear. The Parche is slated to

retire in 2004 and will be replaced by another submarine.

By 2025, the attack submarine force will look

very different, according to the Navy’s current plans.

Forty of today’s submarines will have been retired,

having reached the end of their notional service life

of 30 to 33 years. (For a discussion of how the service life of a submarine is determined, see Box 1.)

The fleet will still have three Seawolf submarines

and 12 Improved Los Angeles class submarines, but

the remainder will consist of 42 submarines from the

Virginia class or its successor—for a total force of 57

attack submarines. As a result, the force in 2025 will

carry about 275 more VLS cells and 450 more weapons than the current fleet (see Figure 2).

The Navy argues that its new Virginia class submarine will be much more capable than the Los Angeles class, especially with respect to quietness and

sensors. The technological advances of the Virginia

should enable it to perform SSN missions more effectively, but those advances will not necessarily make

the Virginia more efficient than earlier submarines.

In other words, the introduction of a new class of

submarine does not appear likely to reduce the overall requirement for mission days. Indeed, the new

capabilities of the Virginia and hoped-for (but not yet

proven) technological improvements might allow it to

Box 1.

Estimating the Service Life of an Attack Submarine

Determining the useful service life of a submarine—

and thus when it needs to be replaced—can be difficult. As recently as 1998, the official service life of

both Los Angeles class attack submarines (SSNs) and

Ohio class Trident ballistic missile submarines was 30

years. The Navy designs an SSN to withstand a specific number of events (such as dives) that stress the

hull, as well as the cumulative effects that routine operations have on materials and equipment. More recently, the Navy studied the material condition of its

submarines and determined that under current operating assumptions, the service life of most SSNs could

be increased to 33 years and that of Trident submarines to 42 years. The Navy expects that new Seawolf

and Virginia class attack submarines will also last for

33 years.

Some Los Angeles class submarines may be able

to operate longer than 33 years, the Navy speculates.

Los Angeles SSNs with hull numbers 719 or above

were constructed with “life of the submarine” reactor

cores, meaning that those reactors could operate for a

full 33 years without needing to be refueled. Refueling a nuclear-propelled submarine is a time-consuming and expensive task. Earlier Los Angeles SSNs,

with earlier-design reactors, were (or will be) refueled

at around the 20-year point. With refueling, those

submarines have enough nuclear fuel to last a total of

38 years under current operating assumptions.

Whether the hulls of those submarines and other major components could last that long is not clear, however. In 10 to 15 years, when those submarines are

approaching 33 years of age, the Navy may analyze

their material condition and determine whether they

can cost-effectively be retained for another five years.

Can the later Los Angeles or even the new Seawolf or Virginia class submarines last longer than 33

years? No one will know until some of those submarines start to reach the end of their notional service life

around 2020. One outcome could be that those later

submarines might be able to last for an additional five

years but refueling them for such a short period would

not be cost-effective. Another conceivable outcome is

that all of those submarines will not last as long as 33

years. Historically, only a few U.S. nuclear attack

submarines were in service for more than 30 years.

The Navy has almost always retired nuclear submarines before 30 years because of reduced requirements

or lower budgets or because the age and condition of

the submarines made them unsuitable for continued

operations.
CHAPTER ONE SUBMARINE REQUIREMENTS AND THEIR IMPLICATIONS FOR THE NAVY’S BUDGET 5

2002 2015 2025

0

500

1,000

1,500

2,000

2,500

3,000

 VLS Cells Weapons

Figure 2.

Total Weapons and VLS Cells in the Attack

Submarine Force in 2002, 2015, and 2025

SOURCE: Congressional Budget Office.

NOTES: This figure assumes that the number of weapons on future Virginia class submarines will remain the same as

on the first ship of that class.

VLS = vertical launch system.

perform new missions, possibly increasing requirements for SSNs.

Evolving Roles and Missions

of Attack Submarines

The attack submarine force can perform a variety of

peacetime and wartime missions. Those missions

include covert intelligence, surveillance, and reconnaissance; covert insertion and extraction of specialoperations forces; covert attack of targets on land

with Tomahawk cruise missiles; offensive and defensive mine warfare; antisubmarine warfare; and antisurface-ship warfare. All of those missions were part

of the attack submarine’s role during the Cold War

(and some were part of that role as far back as World

War II). Since then, however, the types of missions

assigned to SSNs have changed, and they may continue to evolve.

Missions During the Cold War

The principal purpose of U.S. attack submarines during the Cold War was to conduct antisubmarine warfare in the open ocean. Their job was to locate and

trail Soviet submarines, especially ones carrying ballistic missiles, so those subs could be destroyed in the

event of war.

Other important missions included covert intelligence, surveillance, and reconnaissance of the Soviet Union or its allies and the insertion of specialoperations forces. Although most of the fleet’s attack

submarines could conduct those missions, the Navy

converted several submarines to have special capabilities to perform particularly high-value missions.

The development of the Tomahawk cruise missile in the 1970s gave Navy submarines a modern

land-attack capability. The first attack submarines

armed with Tomahawks—the Sturgeon class—could

only launch those missiles horizontally from their

torpedo tubes. Today, many Los Angeles class submarines (as well as the planned Virginia class submarines) have 12 vertical launch system cells from

which to launch cruise missiles.2

 During the Cold

War, attack submarines carried nuclear-tipped versions of the Tomahawk. In the post-Cold War era,

however, Navy ships (other than ballistic missile submarines) do not carry nuclear weapons. All of the

Tomahawk missiles now deployed on attack submarines have conventional warheads.

Current Missions

The primary missions of attack submarines today are

intelligence, surveillance, and reconnaissance (ISR).

The exact nature of those missions is highly classified. In general, the types of ISR missions that submarines can perform include intercepting important

communications of target countries or observing their

military exercises so as to give the United States a

better understanding of those countries’ weapons,

operations, and military doctrine. Navy officials contend that submarines perform only those intelligence2. Those submarines can also launch cruise missiles through their

torpedo tubes, as can the three Seawolf class submarines, which do

not have VLS cells.
6 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

collection missions “for which there is not another

national collection capability to achieve the desired

end.”3

In addition, the submarine force is increasingly

focused on operating in the world’s littoral (coastal)

regions. Most intelligence operations are likely to

take place in fairly shallow waters, since few of the

probable target countries have naval forces capable

of sustained operations away from their coasts.

Submarines have also played an important role

in land-attack operations since the Gulf War. The

Tomahawk missile has been the weapon of choice in

many punitive operations, such as the 1998 cruise

missile strikes on Afghanistan and Sudan and Operation Desert Fox against Iraq in 1998. Tomahawks are

also an effective weapon in the earliest stages of a

broader conflict, when an opponent’s antiair and antiship defenses have not yet been destroyed. During

the Gulf War, for example, two submarines launched

some of the 288 Tomahawks used in the war. And

during the 1999 campaign against Serbia, submarines

launched 25 percent of the Tomahawk missiles used.

In short, different missions are in high demand today

than was the case during the Cold War.4

Nevertheless, some critics have argued that the

attack submarine is a Cold War relic. If its principal

role during that era was to trail Soviet ballistic missile submarines and that mission essentially no longer

exists, then a large fleet of attack submarines may not

be necessary. Some defense analysts who take that

view argue that the United States could make do with

as few as 35 or even 25 attack submarines.5

Future Missions

How might SSN missions evolve in the future? Several studies of that question have been conducted by

the Navy as well as by outside analysts.6

 For example, according to the CJCS study, the intelligence and

surveillance missions that attack submarines perform

today will still be necessary in 2025. Moreover, if

Russia or China emerged as a “peer competitor” of

the United States, trailing its ballistic missile and attack submarines would probably again be a high priority for U.S. submarine forces. The CJCS study predicted that a growing proportion of SSN missions

will take place in the Asia-Pacific region. Today, 26

attack submarines—about half of the force—are assigned to the Pacific Fleet. By 2015, according to the

CJCS study, 41 of the 68 required SSNs would be

needed in the Pacific Fleet “to counter the threat in

the Asia-Pacific region.”7

The changing nature of the security environment, combined with new technologies, could lead to

even greater demands for attack submarines than the

1999 CJCS study envisioned. Of course, new technologies might also handle many of the intelligence

missions that attack submarines now perform.

The Navy has become increasingly concerned

about the proliferation of relatively inexpensive

weapons that could greatly limit its freedom of action, thereby undermining U.S. foreign policy interests. Countries that invested in such weapons as antiship cruise missiles, fast-attack torpedo boats, dieselelectric submarines, and mines could implement an

“access-denial” strategy. That strategy would not attempt to challenge and defeat U.S. naval forces directly. Instead, it would seek to inhibit the Navy’s

operations in a region by strewing coastal areas with

3. Rear Admiral Malcolm I. Fages, Director of Submarine Warfare for

the Chief of Naval Operations, quoted in “The U.S. Submarine

Force Today: Operational Demands Grow as Numbers Fall,” Sea

Power (July 1999), p. 10.

4. Edward C. Whitman, “Submarines in Network Centric Warfare,”

Sea Power (July 1999), p. 33.

5. See Michael O’Hanlon, How to Be a Cheap Hawk: The 1999 and

2000 Defense Budgets (Washington, D.C.: Brookings Institution

Press, 1998), pp. 125-126; and Ivan Eland, Subtract Unneeded

Nuclear Attack Submarines from the Fleet, Foreign Policy Briefing

No. 47 (Washington, D.C.: Cato Institute, April 2, 1998).

6. See, for example, Defense Science Board Task Force, Submarine of

the Future (Department of Defense, Office of the Under Secretary

of Defense for Acquisition and Technology, July 1998); and Naval

Studies Board, Technology for the United States Navy and Marine

Corps, 2000-2035, 9 vols. (Washington, D.C.: National Academy

Press, 1997).

7. Rear Admiral Albert H. Konetzni, “How Many Subs Do We Need?”

Proceedings, U.S. Naval Institute (November 2000), p. 57. Admiral Konetzni is the former commander of the U.S. Pacific Fleet’s

submarine force.
CHAPTER ONE SUBMARINE REQUIREMENTS AND THEIR IMPLICATIONS FOR THE NAVY’S BUDGET 7

mines, putting hundreds of antiship cruise missiles

along the shore, and having several quiet dieselelectric submarines roam littoral waters.

If the Navy’s operations were inhibited, ground

and tactical air forces would also suffer. The Army

and, to a much lesser degree, the Air Force require

substantial amounts of sealift (transport ships) to conduct operations far from U.S. shores. If the Navy

Box 2.

Possible Future Capabilities

of Attack Submarines

The Navy, in conjunction with the Defense Advanced Research Projects Agency, is pursuing a

dramatic leap in attack submarine capabilities

through its Payloads and Sensors Program. The

vision underlying the program is that advances in

missile accuracy and miniaturization could permit

future classes of submarines, including the Virginia, to be equipped with hundreds of missiles

and dozens of underwater and aerial sensors

launched from unmanned underwater or aerial

vehicles. Weapons modules loaded with dozens

of weapons could be deposited on the ocean floor

in a theater of operations and linked back to the

submarine. The sub could then launch those missiles against targets that were far from the weapons modules and whose locations were relayed to

it through the aerial sensors—without ever revealing its position.

If that technology came to fruition, attack

submarines could destroy enemy weapons that

posed a threat to surface ships and arriving

ground and air forces. Cruise missile emplacements, surface-to-air missile batteries, commandand-control systems, and important operating

bases could all be eliminated by weapons that the

opponent had never seen or detected. Once that

was accomplished, other forces could operate

more easily in the theater.

The technological barriers to that vision are

considerable, however. For submarines to operate as described above, substantial leaps in technology would be necessary in a number of areas:

accuracy and miniaturization of ballistic missiles,

connectivity between submarines and aerial or

satellite sensors, and the ability to quickly retarget

strike weapons on board a submarine so they

could destroy mobile targets.

cannot clear the way, sealift and other forces cannot

follow. As the Navy puts it, “In future crises and

conflicts . . . access-denial weapons could make the

projection of U.S. power so costly that the United

States might be deterred from acting.”8

Some analysts see the attack submarine as the

main solution to the access-denial problem. Unlike

surface warships, submarines are stealthy, making

them difficult to detect and locate. That stealth renders them immune to the threats posed by antiship

cruise missiles and fast-attack torpedo boats. (However, a diesel-electric submarine can threaten an attack submarine, and mines can constrain its operations.)

Currently, one major limitation of attack submarines is their small payloads, relative to those of surface ships. Los Angeles class submarines and the

first Virginia class subs each carry fewer than 40

Tomahawk land-attack missiles and torpedoes combined. Another drawback of SSNs is their limited

ability to understand from underwater what is happening on a battlefield. Those problems may have

technological solutions, but probably not in the near

future (see Box 2).

In short, if naval forces as a whole represent the

vanguard of U.S. military power—preparing the path

and securing the beachheads for much larger ground

and air forces in areas where they do not have access

to land bases—then submarines may be key to clearing the way for other naval forces that are more vulnerable to an enemy’s access-denial strategy.

Whether such a broad mission would require more or

fewer submarines than the Navy now says it needs

would depend in part on how the Navy operated its

submarines.

The Resource Implications of

Building a Larger SSN Force

Defense officials’ goals for the attack submarine

force have fluctuated in recent years. The submarine

requirements in the CJCS study represented a sub8. Department of the Navy, Vision . . . Presence . . . Power: A Program Guide to the U.S. Navy (1999), p. 3.
8 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

1990s 2002 To Maintain To Field To Field

0

1

2

3

4

Submarines per Year

(Actual) (Planned) 55 SSNs 68 SSNs

by 2015

76 SSNs

by 2025

Figure 3.

Average Annual Production Rate

for Attack Submarines

SOURCE: Congressional Budget Office.

NOTE: SSN = nuclear-powered attack submarine.

stantial increase from the force goals published two

years earlier in the 1997 Quadrennial Defense Review. That review had determined that the Navy

needed 50 attack submarines to perform necessary

missions. More recently, the Department of Defense

under Secretary William Cohen appeared to endorse

55 as the right size for the SSN force. The Secretary

of Defense’s 2000 Annual Report used language that

supported 55 attack submarines while dropping references to the 1997 goal. However, the 2001 Annual

Report (the last one written by Secretary Cohen) was

more ambiguous and did not mention any force level

as being the right one.9

Although the force goals in the CJCS study represent future requirements, Navy admirals argue that

they already need more than 55 attack submarines. In

the past two years, some admirals and civilian Navy

officials have told the Congress and the media that

the SSN force is overworked—specifically, that submarines on deployment have spent 80 percent to 90

percent of their time under way, mostly performing

missions. That figure is much higher than the Navy’s

notional operating tempo for deployed submarines:

65 percent of their time under way.10 The Navy fears

that if the higher rates continue, they will undermine

the morale of submarine crews (possibly causing

fewer sailors to remain in the service) and shorten the

lives of submarines (by using up their reactor cores

faster). Moreover, the Navy says that the SSN force

has had to decline some missions because it lacked

the submarines to accomplish them.

Meeting the CJCS Force Goals

Building a force of 68 SSNs by 2015 and 76 by 2025

would require a much higher construction rate for

submarines than is now funded. The Navy would

need to build 24 submarines between 2002 and 2009

—an average of 3.0 per year—to meet the requirement for 2015 (see Figure 3). To achieve the goal for

2025, it would have to build 58 submarines between

2002 and 2019—an average of 3.2 per year.11

9. See Secretary of Defense William S. Cohen, Annual Report to the

President and Congress (2000), p. 47; and Secretary of Defense

William S. Cohen, Annual Report to the President and Congress

(2001), p. 60.

10. See the statements of Rear Admiral Albert H. Konetzni, Commander, Submarine Force, U.S. Pacific Fleet, and Rear Admiral

John B. Padgett III, Commander, Submarine Group Two and Navy

Region Northeast, before the Subcommittee on Procurement of the

House Committee on Armed Services, June 27, 2000. Press reports

have also emphasized submarines’ relatively high operating tempo.

See William Matthews and Bradley Peniston, “Taking a Dive: Is the

Navy Wasting Its Best Asset?” Navy Times (March 22, 1999), pp.

16-18; Robert Holzer, “Overwork Strains U.S. Sub Fleet,” Defense

News (March 15, 1999), p. 4; and Don Ward, “New Horizons: As

Subs Surface from Cold War, the View Is Friendlier but Busier,”

Navy Times (November 15, 1993), pp. 14, 18.

11. The Congressional Research Service (CRS) performed a similar

analysis of this issue and reached similar conclusions. CRS, like

CBO, determined that the Navy would need to build 58 submarines

between 2002 and 2019 to meet the 2025 force goal. CRS was

slightly more optimistic than CBO in stating that the Navy would

need to build 20 new submarines between 2002 and 2009 to meet

the 2015 force goal. The difference between that number and

CBO’s estimate of 24 submarines derives from slightly different

assumptions about the service lives of existing Los Angeles class

submarines. CRS assumes that all of them will operate for 33

years, whereas CBO, on the basis of information provided by the

Navy, assumes that some of those submarines will last between 30

and 32 years. See Ronald O’Rourke, Navy Attack Submarine Programs: Background and Issues for Congress, CRS Report for Congress RL30045 (Congressional Research Service, June 1, 2000).
CHAPTER ONE SUBMARINE REQUIREMENTS AND THEIR IMPLICATIONS FOR THE NAVY’S BUDGET 9

1990s 2002 To Maintain To Field To Field

0

10

20

30

40

50

60

70

Percent

(Actual) (Planned) 55 SSNs 68 SSNs

by 2015

76 SSNs

by 2025

Figure 4.

Share of the Navy’s Annual Shipbuilding

Budget Devoted to Attack Submarines

SOURCE: Congressional Budget Office.

NOTES: This figure assumes a future shipbuilding budget of

$10.5 billion per year (adjusted for inflation)—the average under the 2003 Future Years Defense Program.

SSN = nuclear-powered attack submarine.

Boosting submarine construction to meet the

CJCS force goals would require much more money

than the Navy has been spending on submarines. To

reach and sustain the 2015 force level would cost an

average of about $5.4 billion a year between 2002

and 2025 for submarine construction and $2.1 billion

a year for operations, CBO estimates. To reach and

sustain the 2025 force level would require an average

of $6.1 billion per year in submarine construction and

$2.1 billion in operating costs. At that level, the SSN

force would cost about $2.7 million for each mission

day it performed.

The effect on future shipbuilding budgets would

be significant. For example, under the fiscal year

2003 Future Years Defense Program (FYDP), the

Navy plans to spend an average of $10.5 billion per

year on ship construction. If that budget remained

constant through 2025 (adjusted for inflation) and the

Navy chose to build to the 2025 requirement, submarines would account for about 58 percent of ship construction, CBO projects—more than twice the current

average (see Figure 4). Conversely, if the percentage

of ship construction devoted to submarines remained

the same as under the 2003 FYDP, the total budget

for shipbuilding would have to rise to about $30 billion a year.

Sustaining the Existing Fleet

Under Current Construction Rates

and Budgets

Keeping the fleet at 55 attack submarines through

2015 would require fewer resources than building at

a rate to achieve the CJCS force goals. The current

construction rate of one submarine per year will be

sufficient to maintain the fleet at 55 SSNs through

2015.12 If that rate is not increased, however, the size

of the force will fall to 36 by 2025 (see Figure 5). To

prevent that decline, the Navy envisions building an

average of 2.2 submarines a year between 2002 and

2020.13 If it can achieve that rate of construction, the

SSN force will remain at about 55 submarines

through 2030. A fleet that size would cost an average

of $4.5 billion per year for procurement and $1.9 billion per year for operations between 2002 and 2025,

CBO estimates.

During the 1990s, the Navy devoted 14 percent

of its shipbuilding budget to attack submarines, or

about $1.1 billion annually (in 2002 dollars). According to the 2003 FYDP, the Navy expects to devote about 21 percent of its shipbuilding budget to

submarine construction between 2003 and 2007, or

approximately $2.1 billion per year. However, to

maintain 55 submarines, the Navy would need to

spend 43 percent of its shipbuilding budget through

2020 ($4.5 billion a year) on submarines, assuming a

future annual shipbuilding budget of $10.5 billion

(adjusted for inflation). Conversely, if the Navy had

12. That statement assumes that all of the existing Los Angeles class

submarines are refueled to last their full notional service life of 30

to 33 years. At this writing, that appears to be the Navy’s intention.

13. Maintaining a 55-submarine force under a steady rate of procurement would normally require building an average of 1.67 submarines per year. But since 1991, the Navy has ordered only five submarines, an average of 0.5 per year. Thus, a “backlog” of submarine construction is building up. See O’Rourke, Navy Attack Submarine Programs, for a more extensive discussion of the backlog.
10 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

2000 2005 2010 2015 2020 2025 2030

0

10

20

30

40

50

60

70

80

90

100

Number of Attack Submarines

Navy's Long-Term Procurement Plan

Current

Production Rate

Figure 5.

Number of Attack Submarines Through 2030

Under the Navy’s Plan and the Current

Production Rate

SOURCE: Congressional Budget Office.

NOTES: The Navy’s plan assumes an average production rate of

2.2 subs a year between 2002 and 2020, compared with

the current rate of one per year. After 2020, it assumes

a production rate sufficient to maintain a force of 55 attack submarines.

Dashed lines identify the force goals of 55, 68, and 76

submarines.

to keep the share of the shipbuilding budget devoted

to submarine construction the same as under the 2003

FYDP, that budget would have to rise to $22 billion a

year, on average.

SSNs Are Central to the Navy’s

Long-Term Procurement Shortfall

A steady-state comparison of the Navy’s force goals

and its recent shipbuilding budgets shows that attack

submarines represent by far the greatest shortfall that

the Navy faces in its shipbuilding account.14 By the

end of the year, the Navy expects to have devoted 22

percent of its ship construction budget between 1998

and 2002 to attack submarines, or an average of

about $1.9 billion out of $8.8 billion annually. If

those numbers were held constant (a steady state),

they would purchase 30 attack submarines at an average price of $2.1 billion apiece (using CBO’s estimate)—well below the force goal of 55. That shortfall amounts to about $1.6 billion per year (see

Table 2).

Other types of Navy ships, notably ballistic missile submarines, also have shortfalls. But the Navy

will not need to buy a new ballistic missile submarine

until 2020, when the first of the planned force of 14

Trident submarines is retired. Amphibious ships actually have a small “surplus,” in that during the past

five years the Navy has spent more on them than is

necessary to maintain a fleet of 36, the current force

goal.

Bridging the Gap: Basing

Three Attack Submarines

in Guam

Last year, the Navy announced that it would base

three of its SSNs in Guam by the end of 2003.15 The

purpose of the change is to use those submarines

more efficiently in two ways.

First, by moving attack submarines some 3,300

nautical miles west of Pearl Harbor, the Navy will

have SSNs centrally located in the area of responsibility of the Seventh Fleet Commander. As a result,

the time those submarines would otherwise have

spent traveling from Pearl Harbor or San Diego to

their areas of operation in the Far East can instead be

used for conducting missions.

Second, and more significant, stationing submarines in Guam allows them to follow a different operating concept, further increasing the number of mis14. That steady-state analysis divides the force goals for different types sion days they can perform. Attack submarines based of ships by the ships’ estimated service life to determine the average

annual purchases necessary to meet those goals and sustain the resulting force. Those annual purchases are then multiplied by estimates of the unit (per-item) cost for each type of ship. CBO used

the same methodology in its October 2000 study, Budgeting for

Naval Forces: Structuring Tomorrow’s Navy at Today’s Funding

Level.

15. Today, Navy attack submarines in the Pacific Fleet are based at

Pearl Harbor, Hawaii; San Diego, California; and Bangor, Washington. SSNs in the Atlantic Fleet are based at Norfolk, Virginia,

and Groton, Connecticut.
CHAPTER ONE SUBMARINE REQUIREMENTS AND THEIR IMPLICATIONS FOR THE NAVY’S BUDGET 11

Table 2.

Shortfall in Recent Ship Construction, by Type of Ship

Percentage

of Ship

Construction

Budget,

1998-2002

Steady-State

Fleet Resulting

from That Level

of Construction

Current

Force Goal

Difference Between SteadyState Fleet and Force Goal

Number Millions of

of Ships 2002 Dollars

Aircraft Carriers 12 9 12 -3 -380

Attack Submarines 22 30 55 -25 -1,580

Ballistic Missile Submarines/SSGNs 1 1 18a -17a -910a

Surface Combatants 36 110 116 -6 -170

Amphibious Ships 10 38 36 2 50

Support Ships 3 29 70 -41 -350

SOURCE: Congressional Budget Office.

NOTES: This table assumes a future steady-state budget of $8.8 billion for ship construction—the average of actual 2002 funding and the

Navy’s 2003 budget request.

SSGN = nuclear-powered guided-missile submarine.

a. This number may be overstated because it includes the four SSGNs, which the Navy has not said it will replace when they are retired. The

current force goal for ballistic missile submarines is 14.

in the United States typically deploy for a 180-day

stretch every two years or so. Submarines based in

Guam will deploy for periods of up to 56 days, but

much more often, so they will spend about 182 days a

year at sea and 183 days a year in their home port.16

Except for periods of at-sea training, most of the days

in those short deployments will be available for conducting missions (because of Guam’s proximity to

important areas of operation). According to the

Navy, the average number of mission days for submarines based in Guam will be 88 to 123 a year (depending on how the submarine is operated)—about

three times what an SSN provides today.17

Transferring three submarines to Guam will entail some costs, both monetary and personnel-related.

The Navy says it will need to improve military housing, medical services, schools, and maintenance facilities on the island. However, most of the improvements in maintenance will involve moving additional

support staff to Guam rather than building more infrastructure, so the Navy expects the overall cost to

be nominal.

Furthermore, although the planned schedule for

Guam-based subs complies with the Navy’s rules for

personnel tempo, the crews of those submarines will

spend more days a year at sea, on average, than their

counterparts in other submarines. (The personnel

tempo for a submarine based in Guam will be slightly

less than 50 percent, compared with about 48 percent

for a U.S.-based submarine.) The Navy does not

know what effect, if any, that increase will have on

the morale and, ultimately, the retention of personnel.

16. That schedule complies with the Navy’s policies about the amount

of time that sailors can spend away from their home port. Those

policies require that after a deployment of 57 days or more, crews

must spend at least twice as long as the deployment time in their

home port. With the Guam-based submarines, because no individual deployment will be as long as 57 days, a crew can return to its

home port, rest for a few weeks, and then return to sea.

17. Navy briefing to the Congressional Budget Office, 2001. The briefing put that estimate at 100 to 140 mission days per year, but according to the Navy, it did not take into account long-term,

shipyard-level maintenance. The Navy has determined (and CBO

assumes) that a single-crewed attack submarine would spend about

12 percent of its service life in long-term maintenance. When that

time is factored in, 100 to 140 mission days becomes 88 to 123

mission days.
12 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

2000 2005 2010 2015 2020 2025 2030

0

10

20

30

40

50

60

70

80

90

100

Number of SSN Equivalents

Navy's Current Plan

(Includes Three SSNs in Guam)

Force Level Under the

Long-Term Procurement

Plan Without

Guam-Based SSNs

Generally, the Navy’s personnel experts suspect that

retention will be no better or worse than for U.S.-

based subs. (CBO’s analysis suggests that even if

very high bonuses were necessary to retain Guambased submariners, the plan would still be cost-effective. See the discussion of Option III in the next

chapter.)

Finally, Guam is not a good base for Navy personnel to “homestead.” The island offers few shorebased assignments that a submarine officer or crew

member could move to after his or her tour of duty at

sea was finished. Consequently, personnel would

have few opportunities to stay there for any length of

time. In fact, the Navy’s current rules prohibit people

from being assigned to Guam for longer than two

years; the Navy expects to increase that period to

three years to provide some stability to the crews of

the transferred submarines.

How Long Will the Change Last?

Right now, the Navy considers the stationing of three

SSNs in Guam to be a temporary measure, lasting

only as long as those submarines’ remaining service

life (until about 2015).18 When it is transferred, each

submarine will have just completed a major maintenance and refueling overhaul. Thus, it will have

more nuclear fuel available for operations than could

be used over its remaining service life. As a result,

the higher operating tempo associated with Guambased submarines will not reduce their service life to

less than 33 years.

CBO assumed in this study that the decision to

base some SSNs in Guam will be permanent. If the

benefits prove to be as great and the costs as low as

the Navy expects, the service will have a substantial

incentive to continue the practice after the first set of

submarines is retired. However, any replacement

submarines based in Guam would have a service life

of about 27 years rather than the notional 33 years

because the higher operating tempo would use up

their nuclear fuel more quickly.

Figure 6.

Effect on Equivalent Force Levels of Basing

Three Attack Submarines in Guam

SOURCE: Congressional Budget Office.

NOTES: Both the Navy’s current plan and the long-term procurement plan assume an average production rate of 2.2

subs a year between 2002 and 2020, compared with the

current rate of one per year. After 2020, they assume a

production rate sufficient to maintain a force of 55 attack

submarines.

Dashed lines identify the force goals of 55, 68, and 76

submarines.

SSN = nuclear-powered attack submarine.

Effects on Force Goals 

and Procurement

Basing three submarines in Guam will substantially

increase the mission capability of the SSN force. The

Navy estimates that Guam-based attack submarines

could provide 88 to 123 mission days per year, compared with 36 for today’s U.S.-based submarines.19

For the purposes of this analysis, CBO assumed an

average of 106 mission days per year (midway between those numbers). Thus, one SSN based in

Guam would be equivalent to about three SSNs based

in the United States.

18. For example, Rear Admiral Konetzni, the former commander of the

Pacific Fleet’s submarine force, told Inside the Pentagon that the

move was a temporary, “band-aid” solution. See P.J. Skibitshi,

“Pacific Submarines Consider Basing Nuclear Attack Boats in

Guam,” Inside the Pentagon (July 13, 2000), p. 1.

19. The Navy will not know exactly how many mission days Guambased submarines can provide until it actually begins operating

them from that location this autumn.
CHAPTER ONE SUBMARINE REQUIREMENTS AND THEIR IMPLICATIONS FOR THE NAVY’S BUDGET 13

That difference has implications for the CJCS

force goals, the Navy’s long-term procurement plan,

and the current construction rate and budget. The

requirements in the CJCS study (which was released

more than a year before the Navy decided to station

SSNs in Guam) were based on the notion of each

submarine providing an average of 36 mission days

per year. With three submarines in Guam, the force

goals can be reduced to 62 attack submarines by 2015

and 70 by 2025. The average construction rate necessary to meet the CJCS goal in 2025 would thus fall

to 2.7 SSNs per year between 2002 and 2019. That

decline would save an average of about $500 million

annually in potential procurement and operating costs

between 2002 and 2025 and reduce the cost per mission day of the SSN force from $2.7 million to $2.5

million.

Basing three subs in Guam does not fundamentally alter the Navy’s long-term problem, however. If

the Navy can implement its long-term procurement

plan as well as transfer three SSNs to Guam, equivalent force levels will stay well above 55 through 2025

and even exceed the CJCS minimum for that year of

62 attack submarines (see Figure 6). If not, the current production rate of one submarine per year will

keep the equivalent force level at or above 55 for

only one year longer with Guam-based submarines

than without them (until 2016).

Chapter Two

Options for Increasing the Mission

Capability of Attack Submarines

To reduce the cost of meeting its force goals for

attack submarines, the Navy could increase the

number of mission days that the current force

provides. This chapter looks at several ways to do

that, all of which expand on ideas that the Navy intends to implement or that have been discussed in

policy debates. The first option would convert four

retiring Trident submarines to perform missions identified in the 1999 study published by the Chairman of

the Joint Chiefs of Staff. The Congress appropriated

$430 million this year to begin the process of converting those submarines. The second option would

use more than one crew to operate some Virginia

class attack submarines. The third option would base

up to 11 SSNs in Guam, building on the Navy’s plan

to transfer three submarines there from the United

States.

To evaluate those options, the Congressional

Budget Office examined whether they could provide

enough extra mission days to meet the force goals

laid out in the CJCS study. CBO also calculated the

options’ cost per additional mission day (above the

level provided by the Navy’s planned force of 55

SSNs) to compare their cost-effectiveness.1

 Each

option assumes that the Navy will base three SSNs in

Guam indefinitely. In addition, although all of the

options assume that the Navy will implement its

long-term procurement plan, CBO examined how the

options would affect equivalent force levels if the

Navy was unable to increase submarine construction

from the current rate of one per year.

Option I: Convert Four

Trident Submarines to SSGNs

In this approach, the Navy would maintain a force of

55 attack submarines. In addition, as it plans to do,

the Navy would convert four Trident ballistic missile

submarines scheduled for retirement in 2003 or 2004

to a guided-missile, or SSGN, configuration so they

could perform nonnuclear missions. Those SSGNs

would employ a system of dual crews similar to the

one that Trident submarines use now. As a result,

four SSGNs could provide about the same number of

mission days as 12 attack submarines. That increase

would boost the mission capability of the attack submarine force substantially through about 2025. After

that, however, the equivalent force level would fall

below 68 as the SSGNs were retired.

The SSGN Concept

The Navy currently operates 18 Ohio class submarines that carry Trident strategic ballistic missiles.

Ten of those submarines have D5 missiles; the other

eight are fitted with older C4 missiles, which are less

accurate and have a shorter range than the D5. The

Navy plans to upgrade four of the submarines armed

with C4s over the next several years so they can carry

D5 missiles. The other four C4 submarines had been

slated for retirement but will now be turned into

SSGNs instead.

1. For details of how CBO made those calculations, see Appendix B.
16 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

Adapting a Trident submarine for cruise missiles involves altering 22 of its 24 missile tubes to

carry seven conventional missiles each, for a total of

154 missiles per submarine. Those weapons will

give each SSGN about the same land-attack capability as a group of three or four surface combat ships.

In addition to that capability, the SSGNs will have

electronic-warfare, intelligence-collection, communications, navigation, and sonar equipment comparable

to that of the new Virginia class attack submarine.

Further, the space freed up by the two unused missile

tubes will be converted to launching areas or equipment storage for special-operations forces.

What Missions Would SSGNs

Perform?

The Navy has provided conflicting information to

CBO about the missions that SSGNs could perform.

One source suggests that, at a minimum, they could

conduct covert precision strikes with cruise missiles

and clandestine operations with special forces. Other

missions would ultimately depend on the equipment

installed, but according to the Navy, “it is foreseen

that the SSGN would be capable of most of the missions of current SSNs, to include undersea warfare

(with limited torpedo room capacity), sea control,

intelligence, surveillance and reconnaissance, offensive mining, and Naval forward presence.”2

 SSGNs

could also be useful as platforms for demonstrating

new technologies in undersea warfare. However,

they would probably not be as effective as SSNs in

helping aircraft carrier battle groups train, operating

under ice, or conducting antisubmarine warfare exercises with other navies.

Other data provided by the Navy suggest that

the missions an SSGN could perform, at least with

respect to those identified in the CJCS study, would

be limited. In constructing this option, CBO relied

on that more conservative view.

Most of the discussion of SSGNs, both inside

and outside the Navy, focuses on having those submarines available to perform strike (land-attack) or

special-operations missions. But strike was not mentioned in the CJCS study as a required mission for

attack submarines, nor were some of the special operations that the Navy has in mind for SSGNs. Thus, if

SSGNs were used for those purposes, they would

probably not be available most of the time to perform

missions identified in the CJCS study. Ultimately,

how to use SSGNs is a choice for policymakers.

For the purposes of this option, CBO chose to

use the SSGNs to conduct missions identified in the

CJCS study. In a document provided to CBO, the

Navy stated that SSGNs could fully perform 12 percent of the mission days in the CJCS study and partially perform another 10 percent. For analytic purposes, CBO assumed that SSGNs could carry out 17

percent of the CJCS mission days (halving the 10

percent to 5 percent and adding it to the 12 percent).

Mission Days and Force Levels

In a 1999 report to the Congress, the Department of

Defense (DoD) anticipated that with a force of four

SSGNs, two could remain forward deployed in different theaters at all times.3

 Achieving that high level of

forward presence would require retaining the blue/

gold crew model used for operating Trident submarines, albeit with some modifications. (That model is

described in detail in Option II.) Each SSGN would

most likely employ a 224-day operating cycle in

which the submarine would be deployed for 174 days

followed by a 50-day period in port. If the blue crew

took the submarine on patrol, the gold crew would fly

out and change places with the blue crew in the middle of the patrol (see Figure 7).4

 On every third patrol, the SSGN would undergo a process to certify

that it was qualified to perform special operations.

CBO calculated that an SSGN could provide up

to 142 mission days per year. That figure originates

2. Information paper provided by the Navy to CBO, February 4, 2001.

3. See the unclassified portions of Department of Defense, Office of

the Under Secretary of Defense for Acquisition and Technology,

Assessment of Potential Benefits of Converting Trident-Class Ballistic Missile Submarines (SSBNs) to Nuclear-Powered GuidedMissile Submarines (SSGNs), August 1999. (This is the second of

two reports on this subject. The first is Analysis of Converting

Trident-Class Ballistic Missile Submarines (SSBNs) to NuclearPowered Guided-Missile Submarines (SSGNs), June 1999.)

4. Although the Navy has used such an operating concept for ballistic

missile submarines, it has not done so for attack submarines.
CHAPTER TWO OPTIONS FOR INCREASING THE MISSION CAPABILITY OF ATTACK SUBMARINES 17

Figure 7.

Deployment Cycle for an SSGN Assigned to the Atlantic Fleet and Based in King’s Bay, Georgia

Refit

Period

Deployed

to Centcom

Deployed

to Eucom

Refit

Period

Deployed

to Centcom

Deployed

to Eucom

SOF

Cert.

Refit

Period

50 15 65 14 5 65 10 50 15 65 14 5 45 10 20 50

224 Days 224 Days 50 Days

Blue Crew Blue Crew Blue

Gold Gold Crew Gold Crew

SOURCE: Congressional Budget Office based on information from Department of Defense, Office of the Under Secretary of Defense for

Acquisition and Technology, Analysis of Converting Trident-Class Ballistic Missile Submarines (SSBNs) to Nuclear-Powered

Guided-Missile Submarines (SSGNs), June 1999.

NOTES: Shaded areas in the top line represent short periods of transit, in-theater crew exchanges, or maintenance.

SSGN = nuclear-powered guided-missile submarine; Centcom = Central Command; Eucom = European Command; SOF Cert. =

special-operations forces certification, which would occur every third cycle.

from information in DoD’s 1999 report to the Congress, which stated that in the course of three 224-day

operating cycles (672 days), an SSGN would spend

150 days in its home port being refitted, 90 days going to and from a theater of operations, 42 days undergoing crew exchanges and some maintenance intheater, and 20 days for the special-operations certification. The report was trying to quantify presence

(simply being in the theater of operations), however,

so it did not include time spent moving from one location to another within a theater to perform different

missions. CBO added 72 days for in-theater transit to

that list on the basis of historical averages for attack

submarines.5

 Thus, out of 672 days, an SSGN would

devote 298 days to missions—the equivalent of 162

mission days per year.

That number, however, does not take into account the time a submarine spends in long-term,

shipyard-level maintenance. A Trident ballistic missile submarine that has been refueled is expected to

spend about 5 percent of its remaining service life in

long-term maintenance, compared with 12 percent for

an attack submarine. But because an SSGN would be

used more like an attack submarine than a ballistic

missile submarine, CBO chose the 12 percent figure.

Subtracting that time for maintenance reduces the

average annual mission days for an SSGN to 142—

equal to four attack submarines based in the United

States.

As noted above, though, CBO assumes that

SSGNs will be limited in the types of missions in the

CJCS study that they can perform. In accordance

with data given to CBO, this option assumes that

each SSGN will provide about the same number of

mission days as three attack submarines rather than

four. The rest of that time could be used to conduct

missions that are not identified in the CJCS study or

(as discussed in the next section) to train at sea. Nevertheless, the four SSGNs in this option would add

substantially to the mission capability of the attack

submarine fleet until about 2026, when the last of

them would reach the end of its service life (see Figure 8). Replacing those SSGNs with new submarines

5. DoD appears to have excluded port visits from those numbers, so

CBO did as well. Port visits are necessary to give the crews of attack submarines liberty from being cooped up underwater during a

180-day deployment. An SSGN crew would be at sea for only 90

days on a much larger ship.
18 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

2000 2005 2010 2015 2020 2025 2030

0

10

20

30

40

50

60

70

80

90

100

Number of SSN Equivalents

Navy's Current Plan Plus Four SSGNs

Navy's Current Plan

a

a

Figure 8.

Effect on Equivalent Force Levels of

Converting Four Trident Submarines to

Perform Conventional Missions

SOURCE: Congressional Budget Office.

NOTES: This figure assumes that each SSGN would be equivalent to about three SSNs with respect to mission days

provided. Actual force levels would be lower than the

equivalent force levels shown here.

The Navy’s plan assumes an average production rate of

2.2 subs a year between 2002 and 2020, compared with

the current rate of one per year. After 2020, it assumes

a production rate sufficient to maintain a force of 55 attack submarines.

Dashed lines identify the force goals of 55, 68, and 76

submarines.

SSN = nuclear-powered attack submarine; SSGN =

nuclear-powered guided-missile submarine.

a. Includes three SSNs based in Guam, each one of which is

equivalent to about three SSNs based in the United States

with respect to mission days provided.

would probably not be cost-effective unless the Navy

built a new class of ballistic missile submarines.6

Maintenance and Training

In the Navy’s plans (and in this option), most maintenance on an SSGN would take place at the submarine’s home port. The Navy’s notional deployment

cycle for SSGNs provides for some in-theater maintenance, perhaps with the support of a tender. But that

in-theater maintenance period (14 days) is shorter

than the current maintenance period for a Trident

submarine (38 days, all of them spent at the home

port). Therefore, to compensate, the SSGN would

also spend 50 days undergoing maintenance at its

home port, including maintenance on its Tomahawk

missile systems.

In terms of crew training, SSGNs would resemble Trident submarines more than attack submarines.

Unlike attack submarines, they would not perform atsea training prior to deployment. The crew that did

not deploy would conduct its training in the submarine’s home port, similar to the way that the crew of a

Trident sub performs its training, but adjusted for the

difference in missions. That training would occur

primarily at the on-shore training facilities in Kings

Bay, Georgia, or Bangor, Washington. According to

the Navy, “the plan is to use the existing Trident

Training Facilities (TTFs) as much as practical and

the base-line plan includes installing training facilities associated with the Tomahawk systems at the

TTFs, and modifying the ship control trainers to include SOF [special-operations forces] operations simulations.”7

That plan is consistent with the information that

DoD provided to the Congress in its 1999 reports on

converting Trident submarines. Indeed, to achieve

the level of presence envisioned in those reports—

two SSGNs forward deployed at any time—the Navy

would have to use the Trident subs’ existing training

facilities and concepts, which do not provide for atsea training.

In reality, the Navy cannot be certain yet

whether SSGN crews will need at-sea training and

certifications to perform their required missions

(whatever those might be). The Navy is trying to

determine that, although it may have to wait for actual experience with SSGNs to know for sure. 

If it turns out that SSGNs cannot perform their

missions without at-sea training, then the conversion

concept will have been oversold and probably will

6. If the Navy wants to maintain the planned size of the Trident fleet not be able to provide the desired level of overseas

at 14, it will need a replacement for its Trident submarines when

they begin to retire in 2026. At this point, however, it is far from

certain what such a replacement would look like or how much it

would cost. 7. Information paper provided by the Navy to CBO, February 4, 2001.
CHAPTER TWO OPTIONS FOR INCREASING THE MISSION CAPABILITY OF ATTACK SUBMARINES 19

presence. Conversely, if SSGNs can carry out their

missions without at-sea training, then it would validate the concept of having a dual-crewed submarine

perform many of the missions of an attack submarine

(see Option II). 

For the purposes of this option, an SSGN could

spend more than 35 days a year conducting at-sea

training and certifications without undercutting its

effectiveness in performing the missions identified in

the CJCS study.

Other Issues

Some Navy officials are concerned that four SSGNs

(with only two operational at any given time) would

not be able to provide the same geographic coverage

as 12 attack submarines. If some of the missions that

SSGNs can perform needed to be done simultaneously, a few might go unfulfilled. There is no way

to know for certain whether that will be the case 15

or 25 years from now, but it does represent a measure

of additional risk in this option.

Table 3.

Average Annual Costs of Different Options for the Attack Submarine Force (In millions of dollars)

Procurement

Costs

Operation and

Support Costs

Other

Costsa

Total

Costs

Average Annual Costs Through 2007

Navy’s Current Planb 2,870 1,840 0 4,710

Costs in Addition to the Navy’s Current Plan

Build 68 SSNs by 2015 3,500 0 0 3,500

Build 68 SSN equivalents by 2015c 1,540 0 0 1,540

Build 76 SSNs by 2025 2,510 0 0 2,510

Build 76 SSN equivalents by 2025c 1,440 0 0 1,440

Option I: Convert four Trident subs to SSGNs 550 60 0 610

Option IIA: Use dual crews on some SSNs 0 0 0 0

Option IIB: Use three crews to operate two SSNs 0 0 0 0

Option III: Base more SSNs in Guam 0 0 0 0

Average Annual Costs Through 2025

Navy’s Current Planb 4,480 1,870 0 6,350

Costs in Addition to the Navy’s Current Plan

Build 68 SSNs by 2015 880 260 20 1,160

Build 68 SSN equivalents by 2015c 530 140 10 680

Build 76 SSNs by 2025 1,640 230 30 1,900

Build 76 SSN equivalents by 2025c 1,130 170 20 1,320

Option I: Convert four Trident subs to SSGNs 170 190 10 370

Option IIA: Use dual crews on some SSNs 0 110 20 130

Option IIB: Use three crews to operate two SSNs 0 60 10 70

Option III: Base more SSNs in Guam 0 10 10 20

SOURCE: Congressional Budget Office.

NOTE: SSN = nuclear-powered attack submarine; SSGN = nuclear-powered guided-missile submarine.

a. These costs, which include such things as infrastructure improvements, would occur between 2008 and about 2015.

b. Does not include the cost of converting four Trident submarines to SSGNs.

c. This alternative includes the basing of three submarines in Guam, which reduces the total number of attack submarines required under the

Chairman of the Joint Chiefs of Staff’s submarine study to 62 by 2015 and 70 by 2025.
20 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

Table 4.

Cost-Effectiveness of Different Options for the

Attack Submarine Force (In millions of dollars)

Total Cost per

Mission Day

Provided by

the SSN Force

Navy’s Current Plan 2.5

Build 68 SSNs by 2015 2.7

Build 68 SSN Equivalents by 2015a 2.5

Build 76 SSNs by 2025 2.7

Build 76 SSN Equivalents by 2025a 2.5

Option I: Convert Four Trident Subs

to SSGNs 2.2

Option IIA: Use Dual Crews

on Some SSNs 2.2

Option IIB: Use Three Crews

to Operate Two SSNs 2.2

Option III: Base More SSNs in Guam 2.0

SOURCE: Congressional Budget Office.

NOTES: Cost per mission day is calculated using steady-state

estimates of procurement and operation and support

costs. Other costs, such as changes in infrastructure,

are also included.

SSN = nuclear-powered attack submarine; SSGN =

nuclear-powered guided-missile submarine.

a. This alternative includes the basing of three submarines in

Guam, which reduces the total number of attack submarines

required under the Chairman of the Joint Chiefs of Staff’s submarine study to 62 by 2015 and 70 by 2025.

Although present, that risk is probably overstated. The three attack submarines that each SSGN

would nominally replace would not have been deployed at the same time but at different times, to provide more continuous coverage. One SSGN, with its

larger number of mission days, would simply provide

the same level of coverage.

What is not overstated about this option is the

potential loss of flexibility. If a crisis or war occurred and most or all of the Navy’s submarines were

deployed, having 12 attack submarines would give

military leaders more flexibility to meet the emergency than having four SSGNs would. Nevertheless,

because this option envisions maintaining a force of

55 attack submarines, the four SSGNs would represent a force in addition to what the CJCS study says

the United States needs for wartime missions.

Overall Cost-Effectiveness

Option I would be relatively cost-effective through

2026, CBO estimates. It would require some significant investment—a total of approximately $4 billion

to refuel, convert, and arm the SSGNs.8

 Average annual costs through 2007 would be $610 million more

per year than in the Navy’s plan (see Table 3 on the

previous page).9

 However, the cost per mission day

of the total force of attack submarines and SSGNs

would be $2.2 million, substantially less than if the

Navy built an equivalent number of attack submarines (see Table 4). That cost-effectiveness would

not change even if the remaining service life of the

SSGNs was only 15 years rather than the 20 years

that the Navy assumes.

Option II: Use More Than

One Crew on Some Virginia

Class Submarines

This option also envisions a fleet of 55 attack submarines, but some of them would have either two alternating crews (dual crewing), similar to Trident submarines, or three crews rotating between two submarines (multiple crewing). In either case, the force of

55 attack submarines would provide about the same

number of mission days as a force built to meet the

8. That estimate includes the cost of buying Tomahawk missiles to

arm the SSGNs. Navy officials argue that they will not need new

missiles because they plan to convert Tomahawks that are launched

through torpedo tubes to ones that can be shot from VLS cells.

Doing that might save about a billion dollars, improving the costeffectiveness of this option.

9. For the purposes of this analysis, the Navy’s plan does not include

the four SSGN conversions that the President proposed to the Congress in February in the 2003 Future Years Defense Program.
CHAPTER TWO OPTIONS FOR INCREASING THE MISSION CAPABILITY OF ATTACK SUBMARINES 21

CJCS goals of 68 SSNs by 2015 and 76 by 2025—at

much lower cost.

Current Operating Cycles and

Crewing Concepts

Understanding the changes that Option II would

make requires knowing some basic information about

the Navy’s current operating cycles and crewing concepts for submarines. The Navy operates one class of

ship with dual crews: the Ohio class submarines that

carry Trident missiles. The approach used for those

subs is very different from the single-crew operating

concept used for attack submarines. Navy officials

have expressed a number of concerns about applying

the Trident dual-crew model to attack submarines.

The Blue/Gold Crewing Concept for Trident Submarines. The Navy’s current model for using more

than one crew to operate a ship is the blue crew/gold

crew concept used with Trident submarines.10 Under

that operational concept, two crews (named blue and

gold) are assigned to each Trident sub. The blue

crew takes the submarine on a 74-day patrol, after

which it brings the sub back to port and both crews

conduct 38 days of maintenance.11 The gold crew

then takes the submarine on another 74-day patrol

and returns home, at which point both crews again

carry out 38 days of maintenance.

That cycle repeats throughout the 42-year service life of a Trident submarine, broken only for longer periods of maintenance. For example, after 14

years, the sub requires an extended refit period in

which it goes into dry dock for four months. At

about the 21-year mark, the submarine returns to dry

dock for two years, during which its reactor core is

replaced (refueling the submarine) and additional

long-term maintenance is performed. Another extended overhaul period occurs at around the 33-year

mark.

With that cycle, the operating tempo of a Trident submarine (the amount of time, on average, that

it spends under way in a year) is 65 percent, whereas

the personnel tempo (the amount of time, on average,

that a sailor spends at sea in a year) is only about 40

percent. Consequently, a Trident submarine is at sea

for the majority of its service life.

Supporting that operating concept required a

unique effort in submarine design and precise procedures for maintenance and training. First, the Ohio

class submarine was designed and engineered to be

operated in that manner. Specific features were incorporated in the sub to accommodate faster maintenance, such as an extra-large hatch—called a logistics escape trunk—and removable decks to facilitate

the replacement of large pieces of equipment. (Removing large items from a Los Angeles class submarine, by contrast, might require dismantling them onboard the sub, which takes time, or cutting a hole in

the hull to remove them.)

Second, the Navy instituted the Trident Planned

Equipment Replacement Program for conducting periodic, large-scale equipment changes to ensure that

Trident submarines operate with “like-new” equipment during each deployment. Rather than wait for

equipment to fail and be replaced as needed, the

Navy replaces equipment on Trident submarines according to a regular schedule, whether they need it or

not. The maintenance facilities at the Trident submarine bases in Kings Bay, Georgia, and Bangor, Washington, include large dry docks, rail-mobile pier-side

cranes to quickly remove or insert large pieces of

equipment in the submarines, and advanced machine

shops. In addition, those maintenance facilities are

given enough resources to ensure a readily available

supply of parts that a Trident submarine might need.

Consequently, CBO estimates, the annual operating

costs for a Trident submarine are about twice those

for an attack submarine.

The Operating Cycle of an Attack Submarine.

Notionally, the full operating cycle of an SSN is 24

months. The first 18 months make up the interdeployment training cycle (IDTC), followed by a sixmonth deployment (see Figure 9). In the past, the

Navy sent some attack submarines on shorter periods

of deployment. But given the post-Cold War reduction in the force, all SSN deployments now last for

10. A similar concept was used with the previous class of ballistic missile submarines.

11. Until recently, those figures were 77 days of patrol followed by 35

days of maintenance.
22 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

Figure 9.

Current Notional Deployment Cycle for an Attack Submarine

Rest, Maintenance,

and At-Sea Training

Rest, Maintenance,

and At-Sea Training

At-Sea Training

and Maintenance

(Pre-overseas

movement) Deployment

180 Days 180 Days 180 Days 180 Days

SOURCE: Congressional Budget Office based on information from the Navy.

six months in order to make more efficient use of the

time a submarine can spend at sea.12

During the IDTC, the submarine normally operates at sea for a limited amount of time—no more

than 28 days per quarter. During the first year of that

18-month period, the crew periodically takes the submarine to sea for activities such as drills, sound trials,

tactical development exercises, support of other submarines preparing to go on deployment, and port

calls to U.S. cities. (The submarine might also give

underway demonstrations to officials and visitors

during those activities.) In the last six months of the

IDTC, the submarine conducts what is called preoverseas movement as the crew prepares to go on its

next deployment. The crew must spend between 30

and 58 days at sea to pass its predeployment evaluations and certifications.

The crew also performs maintenance and upkeep on its submarine during the IDTC, especially

during the pre-overseas-movement period. The

amount of time devoted to that activity is usually no

more than 35 days per quarter. Moreover, about 28

days of maintenance are supposed to be performed

during deployment. That results in a ratio of maintenance time to at-sea time of 0.87 to 1 (excluding

shipyard-level work).

Over the course of its notional 33-year service

life, an attack submarine will go through 14 deployment cycles. In between deployments, it will undergo several major maintenance periods. They include stints as short as two months (called selected

restricted availabilities) for work at a shipyard. During those periods, the submarine, with some effort,

could be sent to sea again in a fairly short time. At

approximately the 12-year point, the submarine will

undergo a 12-month modernization period in which

major repairs and upgrades are performed at a shipyard. At about the 23-year point, it will return for a

longer period of maintenance and improvement

called an engineering overhaul. During neither of

those more-extensive maintenance periods could the

submarine be recalled to duty quickly.

That operating and maintenance cycle means

that an SSN will spend about four years—or 12 percent—of its service life in long-term maintenance. It

will spend about 37 percent of its time at sea, including training near the submarine’s home port as well

as deployment. An SSN will theoretically spend

about 21 percent of its time on deployment, of which

about 10 percent represents mission days.

In reality, submarines do not always match the

Navy’s notional schedules and cycles. In periods

when submarines are in high demand, the IDTC can

be shortened to return subs to sea more quickly. For

the purposes of this analysis, however, CBO used the

Navy’s notional operating concept in its calculations.

The Navy’s Concerns About Using

More Than One Crew on SSNs

In written statements, Congressional testimony, interviews with the media, and briefings and information

papers provided to CBO, Navy officials have raised

various concerns about the concept of using more

than one crew on attack submarines. Many of those

concerns focus on the differences between dualcrewed Ohio class Trident missile submarines and

single-crewed Los Angeles class attack submarines,

12. That will no longer be true beginning this autumn, when the first of

three attack submarines is transferred to Guam. As explained in

Chapter 1, the operating cycles of Guam-based SSNs will be more

intensive than those of U.S.-based attack submarines.
CHAPTER TWO OPTIONS FOR INCREASING THE MISSION CAPABILITY OF ATTACK SUBMARINES 23

which are the mainstay of today’s SSN fleet. Those

concerns cover three broad areas: maintenance,

training, and the development of new crews.

Maintenance. As noted above, Trident submarines

and their bases were designed and built to support a

dual-crew concept. Many design features of the subs

as well as the Trident Planned Equipment Replacement Program and the design of the subs’ bases facilitate quick refits of a Trident submarine so the second

crew can quickly return it to sea, thereby maintaining

the submarine’s relatively high operating tempo. Los

Angeles class submarines and their home ports have

none of those features, making it difficult for those

submarines to use dual crews. Consequently, none of

CBO’s options envision using more than one crew

for Los Angeles class submarines.

Training. Trident submarines perform essentially

one mission: strategic deterrence. That mission begins as soon as the submarine leaves its home port

and involves slow, quiet patrols in which contact

with other ships and operations in other countries’

waters are avoided. Training for that mission takes

place in the extensive on-shore training facilities at

Trident bases. 

Attack submarines, by contrast, perform multiple missions, far from U.S. shores. According to the

Navy, SSN crews need to conduct extensive at-sea

training for those multiple missions before a deployment; shore training alone might not be effective.

For example, Admiral Bowman, director of the Naval

Nuclear Propulsion Program and the most senior submariner in the Navy, stated that the service would

have to invest in more on-shore infrastructure and

trainers to adopt a dual-crewing concept for SSNs.

But that might not be enough, he argued: “There

may be no substitute for at-sea training.” Similarly,

Rear Admiral Malcolm Fages, former director of undersea warfare for the Chief of Naval Operations,

stated: “We are not at all sanguine that, even if we

had unlimited funds, we could put in place a sufficiently robust training capability so that, in an offcrew status, the crews would be proficient to go to

sea and do those missions.”13

Developing New Crews. The Navy also argues that

it could not put together new submarine crews

quickly. If attack submarines were to begin operating

with more than one crew, the Navy says, developing

the first of those new crews would take at least 10

years. Although some development time would certainly be necessary, 10 years may be an overestimate.

In testimony before the Congress, the Navy has vigorously pressed for a larger attack submarine fleet,

which would also require more crews. It has not indicated that if the construction rate for attack submarines increased to two per year in the 2003 or 2004

budget—resulting in more submarines six or seven

years later—the Navy’s personnel system would be

unable to staff those submarines.

Option IIA: Adapting the Blue/Gold

Crewing Model to Attack Submarines

The discussion above demonstrates that applying a

dual-crew concept to part of the SSN force would

require developing new training and maintenance

concepts for attack submarines as well as expanding

shore-based infrastructure. Further, since not all attack submarines would have dual crews, the Navy

would have to maintain two sets of procedures for its

SSN force: one for single-crewed submarines and

one for dual-crewed submarines. Offsetting those

challenges, however, would be substantial gains in

mission days and overall cost-effectiveness.

Under this option, the Navy would adopt a dualcrew operating concept for its new Virginia class

submarines beginning with the one authorized in

2003, which would be commissioned in 2009. By

2015, nine Virginia class subs would be dual crewed;

by 2025, 19 would have dual crews. Such a schedule

would allow the Navy to develop the additional infrastructure that would be necessary for the concept.

How It Would Work. In this approach, two crews

would take turns conducting maintenance and at-sea

training before taking an attack submarine on a 180-

day deployment. The first crew (say, the blue crew)

would conduct maintenance and the required at-sea

training and certification in the first 180 days, followed by a deployment of equal length (see Figure

10). Before and during the blue crew’s deployment,

the gold crew would be resting, visiting with family,

and training on shore for its deployment. However,

13. See Admiral F.L. Bowman, “Remarks to Corporate Benefactors,”

Submarine Review (April 2001), p. 24. Rear Admiral Malcolm

Fages was quoted in John G. Roos, “Weighing the Options: U.S.

Navy Faces Tough Choices in Modernizing Its Attack-Sub Fleet,”

Armed Forces Journal International (April 2001), p. 54.
24 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

Figure 10.

Notional Blue/Gold Deployment Cycle for an Attack Submarine

Maintenance

and At-Sea

Training Deployment

Maintenance

and At-Sea

Training Deployment

Maintenance 

and At-Sea

Training Deployment

180 Days 180 Days 180 Days 180 Days 180 Days 180 Days

Blue Crew Blue Crew

Gold Crew

SOURCE: Congressional Budget Office.

NOTE: The small bands outside a crew’s regular rotation phase represent one-week periods at sea to help maintain the crew’s proficiency

during the time it is undergoing on-shore training.

during the blue crew’s maintenance and training period, the gold crew might also take the submarine out

to sea for one-week periods to help maintain that

crew’s proficiency.

On the submarine’s return from deployment,

both crews would initially work on conducting necessary maintenance. After a couple of months, however, the gold crew would completely assume maintenance duties and begin its at-sea training and certification. That period would last 180 days and then the

crew would take the submarine to sea for 180 days.

On the sub’s return, the cycle would repeat.

All of the dual-crewed submarines in this option

would be based in Groton, Connecticut. The submarine base there has the most extensive facilities for

maintaining and supporting attack submarines and

thus would be best suited to handle a new way of operating the subs. That concentration, however, might

lead to an excess of mission days provided by the

Atlantic Fleet. To compensate, the Navy could transfer seven Atlantic-based submarines to the Pacific

Fleet. By 2025, some of the dual-crewed submarines

would be needed in the Pacific, given U.S. military

strategy’s increasing emphasis on Asia, as discussed

in the 2001 Quadrennial Defense Review.

The Navy argues that the stealthy characteristics

and technological capabilities of Virginia class submarines will be needed in the Pacific before 2025.

Therefore, to put the dual-crewed Virginias in Groton

—where they could perform missions only in the European and Central Asian theaters and the Western

Hemisphere—might not be wise. However, this option assumes that the first four Virginia class submarines, which would not be dual crewed, would be assigned to the Pacific Fleet. Further, by 2016, the

three submarines based in Guam would also be Virginia class subs (assuming that the Navy replaced the

three Los Angeles class subs it is transferring to

Guam after they were retired).

Mission Days and Force Levels. Using data from

1995 through 1998, the CJCS study assumed that a

single-crewed submarine spends an average of 36

days per year on-station conducting missions. By the

same methodology, a dual-crewed submarine as envisioned in this option would spend an average of 65

days per year on-station conducting missions—an

increase of about 80 percent. (For a detailed discussion of how those numbers were calculated, see Appendix A.)

Those figures imply that the Navy could achieve

the same number of mission days provided by a 68-

submarine force with just 55 SSNs so long as it implemented its current plan—that is, the Virginia class

program remained intact (see Figure 11). Achieving

a force equivalent to 68 attack submarines in 2015

would require that nine of the Virginia class subs that

the Navy is building now or intends to order by 2009

be dual crewed and that the remaining 46 Los Angeles class and Seawolf class submarines remain single crewed. The requirement for 18 Virginia class

submarines by 2015 would be met with respect to
CHAPTER TWO OPTIONS FOR INCREASING THE MISSION CAPABILITY OF ATTACK SUBMARINES 25

2000 2005 2010 2015 2020 2025 2030

0

10

20

30

40

50

60

70

80

90

100

Number of SSN Equivalents

Navy's Current Plan Plus

Dual-Crewed Submarines

Navy's Current Plan

a

a

Figure 11.

Effect on Equivalent Force Levels of Using

Dual Crews on Some Virginia Class Submarines

SOURCE: Congressional Budget Office.

NOTES: This figure assumes that dual crewing would begin with

the fifth Virginia class submarine and that each SSN

operated by a dual crew would be equivalent to 1.8

SSNs with a single crew. Actual force levels would be

much lower than the equivalent force levels shown here.

The Navy’s plan assumes an average production rate of

2.2 subs a year between 2002 and 2020, compared with

the current rate of one per year. After 2020, it assumes

a production rate sufficient to maintain a force of 55 attack submarines.

Dashed lines identify the force goals of 55, 68, and 76

submarines.

SSN = nuclear-powered attack submarine.

a. Includes three SSNs based in Guam, each one of which is

equivalent to about three SSNs based in the United States

with respect to mission days provided.

mission days, though not actual subs. For the Navy

to achieve the equivalent of 76 attack submarines by

2025, 19 of the 30 Virginia class subs that the Navy

plans to have in service would need to be dual

crewed and the other 36 SSNs single crewed. 

If the Navy was unable to raise the construction

rate from one submarine a year, however, the equivalent force level would decline over the next three decades, dropping below 55 by 2025.

Perstempo and Optempo. Compared with the way

the Navy operates attack submarines today, Option

IIA would reduce personnel tempo (perstempo) and

increase operating tempo (optempo). The dual crews

under this option would each have a perstempo of 34

percent over the two-year deployment cycle of a submarine, compared with a notional 48 percent for today’s single crews. That difference might conceivably cause morale problems on single-crewed submarines. At the same time, the optempo of a duelcrewed SSN would rise from a notional 42 percent to

57 percent. In addition, by operating submarines

more intensively, this option would exhaust the reactor of a dual-crewed SSN at around 25 years, reducing its notional service life by eight years compared

with that of a single-crewed submarine.

Addressing the Navy’s Concerns. This option for

dual crewing attack submarines takes into account the

Navy’s concerns about maintenance and development

of new crews. However, it only partially addresses

the Navy’s concerns about training.

Maintenance. The greater optempo of dual-crewed

Virginia class submarines would most likely make

additional maintenance necessary between deployments. Currently, the Navy nominally devotes 35

days per quarter to routine maintenance and upkeep

of an attack submarine when it is not either deployed

or in long-term maintenance or overhaul. The Navy

could increase that number significantly—by about

two-thirds, to 56 days per quarter—for dual-crewed

submarines and still keep the ratio of routine maintenance to time at sea almost the same as for a singlecrewed attack submarine (0.82 to 1 for the former

compared with 0.87 to 1 for the latter). In addition,

CBO assumed that the dual-crewed submarines under

this option (as well as the multiple-crewed and

Guam-based SSNs in Options IIB and III) would

spend more time in shipyard-level maintenance than

a single-crewed attack submarine does. For that reason, CBO did not assume that any substantial design

modifications to the Virginia class would be necessary other than the ones the Navy is already planning.

Training. The Navy’s plan for operating converted

Trident submarines in an SSGN configuration raises

questions about how much at-sea training is really

necessary for attack submarines (assuming that the

infrastructure for shore-based training is expanded).

As noted in Option I, the Navy has stated in reports

to the Congress and briefings to CBO that it believes

an SSGN will be capable of performing most of the
26 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

missions of an attack submarine, including strike,

insertion of special-operations forces, undersea warfare, sea control, intelligence collection, offensive

mining, and forward presence. Even so, the Navy

plans to continue using the Trident’s blue/gold crewing concept to operate those submarines, which

would mean that essentially all crew training would

be conducted on shore. If the Navy can implement

that concept for SSGNs, it might also be able to do so

for dual-crew attack submarines. Nevertheless, Option IIA would continue to provide a 180-day period

before deployment in which the crew of an attack

submarine could take the ship to sea for 28 days per

quarter to perform at-sea training and certifications.

During that 180-day period, the alternate crew

would have several opportunities to conduct at-sea

training. It could spend about seven days per quarter

training at sea when its submarine was in home port.

Those at-sea training opportunities would mean that

the largest gap between a crew’s times at sea would

be 180 to 190 days, compared with 130 days for the

crew of an SSGN or 150 days for the crew of a Trident ballistic missile submarine.

Option IIA assumes that some investment would

be necessary to increase the size of shore-based training facilities for SSNs. The principal training facility

for attack submarines is located in Groton, Connecticut. As part of the overall downsizing of the submarine force, that facility was reduced. Thus, it could

not easily accommodate training the extra nine to 19

submarine crews that would exist under this option

without additional training equipment, instructors,

classrooms, and associated infrastructure. SSN training facilities in San Diego or Hawaii, which are less

extensive than those in Groton, would also need some

additional equipment and facilities. CBO estimates

that the total cost to expand SSN training and other

facilities would be about $500 million.

Developing New Crews. This option would not attempt to employ dual crews for large portions of the

attack submarine fleet quickly. Nevertheless, the

Navy would have to recruit and retain nine additional

crews by 2015 and 19 by 2025. Compared with its

current plan for a 55-submarine force, the Navy

would need an extra 380 officer billets and 2,000 enlisted billets by 2015. By 2025, an additional 800

officer billets and more than 4,200 enlisted billets

would be necessary.

How much of a challenge would those additions

pose for the Navy? CBO questioned Navy officials

about whether the service could recruit and train 13

additional submarine crews by 2015 and 21 by 2025.

In a thorough and highly detailed answer, the officials stated unambiguously that the Navy could meet

those goals. Thus, the smaller addition—nine crews

by 2015 and 19 by 2025—that this option would require to dual crew Virginia class SSNs beginning

with the fifth ship should prove slightly easier to

achieve.

Overall Cost-Effectiveness. Although this option

would pose some policy challenges for the Navy, it

would improve the cost-effectiveness of the SSN

force. This option would cost an average of $130

million more per year than the Navy’s plan between

2002 and 2025 (mostly for operations and support),

but it would reduce the force’s total cost per mission

day by $0.5 million. Starting with a base force of 55

single-crewed attack submarines (including three in

Guam) that provides a certain number of mission

days, the average cost to meet the CJCS requirements

under this option would be $2.2 million per mission

day. By comparison, building more attack submarines to meet those goals would cost an average of

$2.7 million per mission day.

Even if some design modifications were necessary to accommodate the dual-crew concept, the costeffectiveness of this option would not change. For

example, an additional $1 billion in design changes

to the dual-crewed SSNs would keep the cost per

mission day of the SSN force under this option at

$2.2 million.

Option IIB: Using Three Crews

to Operate Two Submarines

Adopting the Trident blue/gold crewing model is not

the only way to improve the efficiency of attack submarines by using more than one crew. This option

envisions an operating concept in which three crews

would rotate between two Virginia class submarines

on nine-month deployments. Under this option, eight
CHAPTER TWO OPTIONS FOR INCREASING THE MISSION CAPABILITY OF ATTACK SUBMARINES 27

Figure 12.

Notional Deployment Cycle for Two Submarines Operated by Three Rotating Crews

Submarine A

On Deployment At Home 

Blue Crew Gold Crew Orange Crew Gold Crew Orange Crew Blue Crew

90 Days 90 Days 90 Days 90 Days

(45 at sea)

90 Days

(45 at sea)

90 Days

(45 at sea)

Submarine B

At Home On Deployment 

Gold Crew Orange Crew Blue Crew Blue Crew Gold Crew Orange Crew

90 Days

(45 at sea)

90 Days

(45 at sea)

90 Days

(45 at sea)

90 Days 90 Days 90 Days

SOURCE: Congressional Budget Office.

submarines would operate with multiple crews in that

manner by 2015 and 14 submarines by 2025. The

principal advantage of this option is that it would

change the crewing model for fewer SSNs than Option IIA would. However, that change would represent the most significant departure from the Navy’s

current practices for either attack submarines or ballistic missile submarines of the options that CBO examined; thus, implementing it would pose the greatest challenges for the Navy.

How It Would Work. In this approach, three crews

would take turns operating a pair of Virginia class

submarines. When one submarine was on deployment for 270 days, the other submarine would be in

the same home port so that the crews not on deployment could use it for at-sea training.

The schedules of the two submarines would be

divided into 90-day increments (see Figure 12). One

crew (say, the blue crew) would deploy with the first

sub for three months. Meanwhile, the gold crew

would be training with the second submarine, preparing for deployment. The orange crew would not receive any at-sea training during those three months.

Near the end of that period, the gold crew would be

flown to the theater of the deployed submarine to

exchange places with the blue crew.14 The orange

crew would then assume control of the second submarine to prepare for its deployment. The blue crew,

which had flown home, would rest and not receive

any at-sea training during that second 90 days. After

that second three-month period, the orange crew

would rotate out to the deployed submarine, eventually bringing it back to the home port, while the blue

crew was preparing the other submarine for its deployment. Each deployed submarine would stay at

sea for a total of 270 days, three months longer than

is the Navy’s current practice. 

In contrast to the Trident model, the crews in

this option would not all have the same operational

experience. The blue crew would always conduct its

deployment with the submarine that it had used for

training. The other two crews would never have that

advantage. The blue crew would always take a submarine on deployment and the orange crew would

14. The concept of rotating crews to a forward-deployed submarine was

suggested in Department of Defense, Analysis of Converting

Trident-Class Ballistic Missile Submarines (SSBNs) to NuclearPowered Guided-Missile Submarines (SSGNs). As described in

that report, the blue crew would take the SSGN on deployment and

the gold crew would be rotated to the submarine halfway through its

patrol, eventually bringing it home.
28 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

2000 2005 2010 2015 2020 2025 2030

0

10

20

30

40

50

60

70

80

90

100

Number of SSN Equivalents

Navy's Current Plan Plus

Multiple-Crewed

Submarines

Navy's Current Plan

a

a

always bring it back. The gold crew would not do

either; thus, it would never conduct long transits.

However, all three crews would be at sea for comparable periods.

Mission Days and Force Levels. Submarines that

used multiple rotating crews as envisioned in this

option would spend an average of 73 days per year

conducting missions over the course of their service

life—twice the average for a single-crewed submarine. Achieving a force equivalent to 68 submarines

by 2015 would require the Navy to begin this

multiple-crewing concept with the Virginia class submarines authorized in 2004. By 2025, when 14 Virginia SSNs would employ multiple crews, the equivalent force level would exceed 76 (see Figure 13).

Like Option IIA, this alternative would meet the requirement for 18 Virginia class submarines by 2015

with respect to amount of presence though not actual

number of submarines.

Perstempo and Optempo. If, as this option assumes, crews spent half of their three-month training

period at sea, their perstempo would be exactly 50

percent. That figure is slightly higher than the current perstempo for single-crewed submarines (48 percent) but essentially equal to the perstempo anticipated for the submarines that the Navy is stationing

in Guam. The optempo of the multiple-crewed submarines would be 63 percent, higher than in Option

IIA. That higher operating level would reduce the

reactor life of a multiple-crewed submarine to 24

years, the shortest among the options in this study.

Addressing the Navy’s Concerns. This option answers the Navy’s concern about at-sea training better

than Option IIA does, but it could require very controlled design and construction parameters for the

submarines that would use multiple crews. Developing the additional crews would not be difficult, although the Navy would have to find suitable sites for

exchanging crews in-theater. Maintenance, however,

would be a greater challenge for the Navy than under

Option IIA’s dual crewing.

Maintenance. In this option, multiple-crewed submarines would spend nine months at sea, compared with

six months for today’s single-crewed SSNs. The operating cycle envisioned in this option would reduce

the subs’ ratio of maintenance time to at-sea time to

0.65 to 1 (from the current ratio of 0.87 to 1). 

Keeping a submarine at sea longer increases the

risk of not being able to maintain it in good working

order. As mentioned in Option IIA, the crew of an

attack submarine on deployment notionally conducts

maintenance about 28 days out of 90. In practice, the

crew is always performing some degree of maintenance on the ship’s systems. Crew members can fix

some problems, but others require the support of

maintenance facilities on a tender or, better yet, at the

home port. Although a submarine may encounter a

difficult repair problem at any point in its deployFigure 13.

Effect on Equivalent Force Levels of Using

Multiple Crews on Some Virginia Class

Submarines

SOURCE: Congressional Budget Office.

NOTES: This figure assumes that three crews would take turns

operating two Virginia class submarines and that each

submarine crewed that way would be equivalent to two

SSNs with single crews. Actual force levels would be

much lower than the equivalent force levels shown here.

The Navy’s plan assumes an average production rate of

2.2 subs a year between 2002 and 2020, compared with

the current rate of one per year. After 2020, it assumes

a production rate sufficient to maintain a force of 55 attack submarines.

Dashed lines identify the force goals of 55, 68, and 76

submarines.

SSN = nuclear-powered attack submarine.

a. Includes three SSNs based in Guam, each one of which is

equivalent to about three SSNs based in the United States

with respect to mission days provided.
CHAPTER TWO OPTIONS FOR INCREASING THE MISSION CAPABILITY OF ATTACK SUBMARINES 29

ment, staying at sea longer increases the probability

that it will need the support of a tender to perform

necessary maintenance during its voyage.

In an attempt to minimize maintenance problems, this option envisions adopting a more aggressive maintenance concept for the Virginia class submarines that would use multiple crews. Specifically,

the Navy would need to replace important components at more regular intervals—as it does with Trident submarines—rather than wait until they failed or

were about to fail. Although this option’s notional

operating cycle probably includes enough time to

perform all necessary maintenance, sending the

multiple-crewed submarines to sea with their important components replaced would help reduce the risk

of breakdowns.

A further complication associated with this option involves scheduling the longer, shipyard-level

maintenance periods (when a ship is unavailable for

at-sea operations). The submarines with multiple

crews would need to undergo such periods in pairs, in

the same way that they operated.

Training. One advantage of this option is that it

would provide up to 45 days of training at sea prior

to each 90-day deployment. Thus, the longest period

in which a crew would not be able to go to sea would

be 90 days. That number is a considerable improvement over Option IIA, in which crews would spend at

least 180 days without the opportunity to practice and

maintain their skills at sea.

A disadvantage of this option’s schedule, however, is that it would not provide enough time at sea

to perform all of the training and certifications necessary for a submarine to deploy with an aircraft carrier

battle group. Thus, the submarines that used multiple

crews might be limited to independent operations.

Although such operations represent the majority of

attack submarines’ missions, that limitation would

create additional complexity in operating the SSN

force and, therefore, in providing support to battle

groups.

Another element of complexity is that in order

for the at-sea training to be as effective as possible,

submarines would have to be designed as well as operated in pairs to minimize any engineering differences between the sub used for training and the one

taken on deployment. (Alternatively, the entire class

would need stringent configuration controls.) Submarines, like other types of ships, are not all exactly

alike. The Navy and submarine manufacturers try to

ensure that each new sub incorporates the most up-todate technology available. With a construction rate

of one per year, every submarine is a little different

from every other. How much that difference actually

matters would depend on the specific technological

discrepancies between two submarines. If the construction rate for attack submarines remained at one

per year rather than rising to more than two, this option could still work, but it would require discipline

in the engineering process from year to year.

How difficult would achieving such uniformity

be? If two manufacturers each built one complete

submarine every other year, this approach might be

unworkable. However, the current teaming arrangement between Electric Boat and Newport News Shipbuilding, in which the same company builds the same

sections for each submarine, has made it much easier

to maintain such engineering discipline. Furthermore, the Virginia class submarine is the first Navy

ship to be designed entirely by computer before any

construction has begun. As a result, the first Virginia

class submarine has had 90 percent fewer design

changes during construction than the third Seawolf

class submarine had at the same stage.

Developing and Exchanging Crews. This option

would require far fewer additional crews than Option

IIA: only four by 2015 and seven by 2025. However, the Navy would have to plan, and find appropriate locations for, the in-theater crew exchanges. Attack submarines on routine deployments periodically

visit foreign ports as part of exercises as well as to

give the crews some shore leave. Whether a foreign

government would allow such visits for the purpose

of exchanging crews is not clear. Missing a crew

exchange would complicate the rest of the schedule

of both submarines as well as potentially violate perstempo rules.

Overall Cost-Effectiveness. This option is every bit

as cost-effective as Option IIA. It would cost slightly

more than the Navy’s current plan—an average of

$70 million more per year between 2002 and 2025—

but, like Option IIA, it would reduce the average cost

per mission day of the SSN force to $2.2 million. On

the flip side, the policy changes required to carry out

this option are more dramatic, and the risks that the
30 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

2000 2005 2010 2015 2020 2025 2030

0

10

20

30

40

50

60

70

80

90

100

Number of SSN Equivalents

Navy's Current Plan with Eleven

SSNs in Guam by 2025

Navy's Current Plan

(Includes Three SSNs in Guam)

Navy would assume are greater, than in any of the

other options.

Option III: Base More Attack

Submarines in Guam

Under this option, the Navy would continue to operate a fleet of at least 55 attack submarines, but it

would station seven of them in Guam by 2015 and 11

by 2025. Unlike altering crewing concepts, basing

another four to eight submarines in Guam would not

be conceptually difficult to do. The additional submarines would operate in exactly the same way as

those the Navy already plans to base in Guam. Moreover, although this approach would require some upfront spending to improve the infrastructure on

Guam, it would produce a more cost-effective fleet

than any of the other options examined in this study.

Mission Days and Force Levels

As explained in Chapter 1, a Guam-based submarine

would spend an average of 106 days per year conducting missions, compared with 36 for a U.S.-based

SSN today. Those additional mission days would

come from a combination of reduced transit time and,

especially, the different operating concept that the

Navy plans to use for attack submarines stationed in

Guam. Consequently, a force made up of seven

Guam-based attack submarines and 48 other attack

submarines would provide the same number of mission days as a force of 68 SSNs based in the United

States. Similarly, a force of 11 Guam-based submarines and 44 other attack submarines would provide

slightly more mission days than a force of 76 SSNs

based in the United States (see Figure 14).

Furthermore, if the additional submarines assigned to Guam by 2015 were from the new Virginia

class, they would almost satisfy the mission-day requirement associated with the goal of having 18 Virginia class submarines by 2015. That would be true

even if the Navy was unable to increase the construction rate for Virginia class submarines above one per

year. In that case, 11 Virginia class submarines

would be operational by 2015; if three of them were

based in Guam, the force could provide an equivalent

number of mission days as 17 Virginia class submarines based in the United States. (Guam is not the

Navy’s only alternative for basing submarines outside the United States. For information on how other

forward-basing options would affect force levels, see

Box 3.)

Maintenance and Training

The Navy expects that any short-term maintenance

necessary for its three Guam-based submarines will

be done in that port. But more-major overhauls, reFigure 14.

Effect on Equivalent Force Levels of Basing

Eleven Submarines in Guam by 2025

SOURCE: Congressional Budget Office.

NOTES: This figure assumes that each attack submarine based

in Guam would be equivalent to about three SSNs

based in the United States. Actual force levels would be

much lower than the equivalent force levels shown here.

The Navy’s plan assumes an average production rate of

2.2 subs a year between 2002 and 2020, compared with

the current rate of one per year. After 2020, it assumes

a production rate sufficient to maintain a force of 55 attack submarines.

Dashed lines identify the force goals of 55, 68, and 76

submarines.

SSN = nuclear-powered attack submarine.
CHAPTER TWO OPTIONS FOR INCREASING THE MISSION CAPABILITY OF ATTACK SUBMARINES 31

Box 3.

Other Forward-Basing Options

for Attack Submarines

Although the Congressional Budget Office used

Guam to illustrate the potential gains from basing

more attack submarines near their likely areas of

operation, that island is not the only place in the

Pacific where U.S. submarines could be stationed.

The United States has formal alliance relationships with Japan, South Korea, the Philippines,

and Australia. It also bases an aircraft carrier battle group in Japan. What advantage would there

be to stationing attack submarines in those countries?

A U.S.-based submarine performs 36 mission

days per year, on average, and a submarine based

in Guam will perform 88 to 123 mission days,

according to the Navy. If the Navy was able to

station attack submarines in Japan or South Korea, they could probably provide eight to 10 more

mission days per year than subs based in Guam,

CBO estimates, if their mission area was the

western Pacific. Submarines based in the Philippines would provide about the same number of

mission days as those based in Guam, under the

same assumption. Submarines stationed in Australia might provide five to seven more mission

days per year than subs based in Guam if their

mission area was the Middle East.

Those estimates do not take into account the

political ramifications or the potential costs of

such a move. But they do illustrate the relative

advantages of finding overseas bases for Navy

submarines, especially across the vast Pacific

Ocean.

quiring between two and 16 months in a shipyard,

will be conducted in the continental United States or

Pearl Harbor. If the Navy based more subs in Guam,

it might want to build better repair facilities there.

CBO assumed that the Navy would do so and included those costs in its analysis.

Shore-based training would be a more complicated issue. Guam does not have adequate training

facilities, so the Navy would either have to build

some there or fund a larger travel budget to fly the

sailors from Guam-based submarines to training facilities in Hawaii or Connecticut (the current plan for

the three subs that will be based in Guam by next

year).

Other Issues

Although this option would enable the Navy to meet

the CJCS force goals fairly easily with the currently

planned fleet, it would have drawbacks. Basing a

large force of attack submarines in Guam might prevent them from providing support to carrier battle

groups that were preparing to go on deployment or

from providing other services to the Navy fleet. In

addition, the Navy would have to invest substantially

in the shore facilities on Guam to accommodate a

doubling—and ultimately a tripling—of submarines,

crews, and their families. Even so, the quality of life

of those crew members and families could suffer.

Battle-Group Support and Fleet Services. Half of

the Pacific Fleet’s aircraft carrier battle groups are

based in San Diego. If the submarines transferred to

Guam under this option were removed from San

Diego, the SSN presence there would end, making it

difficult for attack submarines to train with carrier

battle groups and thus to support them during their

deployments. That difficulty may not matter if more

and more of the submarine force’s missions are

geared toward intelligence collection. However, the

issue would not arise if the submarines transferred to

Guam were taken from Hawaii rather than San

Diego. 

Regardless of the source of the transferred submarines, another effect of this option would be to

reduce the availability of SSNs to assist other Navy

units in training exercises. Attack submarines periodically serve as the opposition force for surface

ships practicing antisubmarine warfare. This option

would offer fewer opportunities for that, unless a surface unit took time for such practice during its deployment in the western Pacific (assuming that it was

passing near Guam).15

15. A relatively inexpensive yet highly effective solution to that problem would be for the Navy to purchase several diesel-electric submarines to serve as an opposition force on each coast for ships practicing antisubmarine warfare. See Congressional Budget Office,

Budget Options (February 2001), pp. 137-138.
32 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

Infrastructure. Probably the largest monetary cost

associated with Option III is the additional investment that would be needed in Guam’s shore-based

infrastructure. To accommodate four to eight more

submarines on the island (and their crews and families), the Navy would have to build a floating dry

dock and additional pier spaces, barracks, stores,

medical facilities, and schools—all of the things

needed for a submarine base equivalent to the one in

San Diego. Those additional facilities would cost

$200 million, CBO estimates.16

Quality of Life. A potential difficulty with this option—as with the Navy’s decision to base three submarines in Guam—is the quality of life of the sailors

and their families. As noted in Chapter 1, Guam does

not offer the same homesteading opportunities as

submarine bases in San Diego and Pearl Harbor. At

those large bases, it is relatively easy for members of

a submarine crew to find other jobs in the Navy when

they finish their sea tours.17 Thus, they and their

families can put down roots and stay in one place

longer than a few years. Such opportunities are few

in Guam. That might become less true if the Navy

adopted this option and invested in a much larger

shore infrastructure. But even if that happened, the

opportunities would not match those of places like

San Diego or Honolulu—in part because there would

be many fewer chances for the spouses of submariners to find jobs in the neighboring community.

If the Navy found that Guam-based duty led to

much lower levels of retention for submariners, monetary bonuses might help. But there is no way to

know for certain at this point because the Navy has

not based submarines in Guam for more than 20

years and will not begin doing so until the end of the

year.

Overall Cost-Effectiveness

Offsetting the possible drawbacks of this option is its

cost-effectiveness—the greatest of any of the options

in this analysis. Basing additional submarines in

Guam permanently would not cost much more than

the Navy’s current plan for a 55-SSN force. The

principal additional cost would be for infrastructure.

In return, the cost per mission day of the SSN fleet

would fall to $2.0 million, less than in any of the previous options and substantially lower than if the

Navy built a larger submarine force. Even if the

Navy found that it had to pay each crew member of a

Guam-based submarine an extra $25,000 per year as

a retention bonus, the cost per mission day under this

option would not change significantly. 

Implications of the Options

A number of conclusions emerge from the analysis of

the options. First, transferring an attack submarine to

Guam would be more cost-effective than building a

new SSN, using an alternative crewing pattern, or

converting and operating a Trident submarine in an

SSGN configuration. Each mission day gained by

building a new submarine would cost $2.7 million, by

far the most expensive choice (see Table 5). ConTable 5.

Relative Costs of Different Ways to Add

Mission Days to the Attack Submarine Force

(In millions of dollars)

Cost per

Additional

Mission Day

Provided

Build a New Submarine 2.7

Convert a Trident Sub to an SSGN 0.8

Operate an SSN with Two Crews 1.2

Operate an SSN with Three Crews

per Two Subs 0.9

Transfer an SSN to Guam 0.2

SOURCE: Congressional Budget Office.

NOTE: SSGN = nuclear-powered guided-missile submarine; SSN

= nuclear-powered attack submarine.

16. Even if CBO has greatly underestimated the cost of building a submarine base in Guam, Option III would still be far more cost-effective than the others in this study.

17. Although San Diego is not a large submarine base, it is home to

three aircraft carriers and their battle groups.
CHAPTER TWO OPTIONS FOR INCREASING THE MISSION CAPABILITY OF ATTACK SUBMARINES 33

verting a Trident sub to an SSGN or using more than

one crew to operate a Virginia class submarine would

cost between $0.8 million and $1.2 million per additional mission day provided. Transferring an SSN to

Guam would cost just $0.2 million for each mission

day it added. Those results do not imply that transferring additional submarines to Guam is unequivocally the best approach, however. Other factors, such

as those discussed in this study, must be considered

in determining where an additional dollar spent on

the submarine force should go.

The relative cost-effectiveness of the options is

not particularly sensitive to changes in assumptions

about operating or procurement costs. If a dual- or

multiple-crewed attack submarine actually cost as

much to operate as an SSGN or a Trident ballistic

missile submarine (a reasonable upper limit) or even

twice as much as a single-crewed submarine, Options

IIA and IIB would still be cheaper per additional mission day provided than building new submarines

would be (see Table 6). Further, if procurement costs

for new submarines were lower than what CBO assumed, the relative cost-effectiveness of the options

would be virtually unchanged. (And if procurement

costs were substantially higher than CBO’s estimate,

the cost per additional mission day for submarine

construction would worsen considerably relative to

the costs for the alternatives.) Thus, to the extent that

the costs of producing or operating attack submarines

are uncertain, all four options would still be substantially more cost-effective for the Navy than building a

larger submarine force would be.

A second conclusion of this analysis is that if

the official force goal remained at 55, these options

Table 6.

How CBO’s Estimates of Cost per Additional Mission Day Would Change

Under Alternative Assumptions (In millions of dollars)

Alternative Cost Assumptions

CBO’s

Estimate

Operating Costs

for Non-SingleCrewed or GuamBased SSNs Are

Equal to Those for

Trident SSBNs

Operating Costs

for Non-SingleCrewed or GuamBased SSNs Are

Equal to Twice

Those for SingleCrewed SSNs

Operating Costs

for Non-SingleCrewed or GuamBased SSNs Are Equal

to Twice Those for

Single-Crewed SSNs

and Procurement Costs

Are 20 Percent Lower

Operating Costs

Are Equal to

CBO’s Estimate

but Procurement

Costs Are

20 Percent Higher

Build a New

Submarine 2.7 2.7 2.7 2.4 3.1

Convert a Trident

Sub to an SSGN 0.8 0.8 0.8 0.8 0.8

Operate an SSN

with Two Crews 1.2 1.8 1.9 1.7 1.3

Operate an SSN

with Three Crews

per Two Subs 0.9 1.5 1.5 1.4 1.0

Transfer an SSN

to Guam 0.2 0.7 0.7 0.6 0.3

SOURCE: Congressional Budget Office.

NOTE: SSN = nuclear-powered attack submarine; SSBN = nuclear-powered ballistic missile submarine; SSGN = nuclear-powered guidedmissile submarine.
34 INCREASING THE MISSION CAPABILITY OF THE ATTACK SUBMARINE FORCE March 2002

2000 2005 2010 2015 2020 2025 2030

0

10

20

30

40

50

60

70

80

90

100

Number of SSN Equivalents

Option III Option IIB

Option IIA

Option I

a

a

b

could help delay for many years the need to increase

the production rate for SSNs. The options assume

that the Navy will implement its long-term procurement plan to keep the size of the attack submarine

force at 55. However, as Chapter 1 illustrated, carrying out that plan could be difficult because of its cost.

If the construction rate remained at the current

level of one submarine per year, for how long could

the approaches represented in these options maintain

an SSN force equivalent to 55? Option I would sustain that level until 2023 (see Figure 15). But because of the six-year interval between authorizing a

new submarine and fielding it, the production rate

would have to increase to two or more SSNs per year

in 2017. Under Options IIA and IIB, production

would have to increase in 2013 or 2021, respectively,

to maintain a force equivalent to 55 SSNs—assuming

that all new Virginia class submarines after the

fourth ship were dual or multiple crewed rather than

the smaller numbers envisioned in the options. Finally, if the Navy based as many as 12 SSNs in Guam

(probably the largest number it might reasonably

want stationed there), the production rate would not

have to increase until 2022. Under all of those scenarios, however, the SSN force would fall below 55

actual submarines (as opposed to their equivalent in

mission days), which is the wartime requirement

stated in the CJCS study.

Figure 15.

Equivalent Force Levels Under Various Options, Assuming a Construction Rate

of One Attack Submarine per Year

SOURCE: Congressional Budget Office.

NOTES: See the text for a description of the options.

The horizontal dashed line identifies the force goal of 55 submarines.

SSN = nuclear-powered attack submarine.

a. Equivalent force level assuming that all new Virginia class submarines after the fourth ship use dual or multiple crews (rather than the

smaller number of submarines included in the option).

b. Equivalent force level assuming that 12 attack submarines—about two squadrons—are based in Guam (rather than the 11 submarines

included in the option).
CHAPTER TWO OPTIONS FOR INCREASING THE MISSION CAPABILITY OF ATTACK SUBMARINES 35

A third conclusion of the analysis is that adopting the new crewing concepts in Options IIA or IIB

would require the Navy to make substantial changes

in the way attack submarines operate, both as standalone units and as part of broader fleet operations.

However, such changes do not appear to be any more

radical—indeed, in some ways are less radical—than

what the surface Navy is proposing with the new

DD(X) destroyer, whose crew would eventually be

one-third the size of a destroyer crew today. If the

Navy executes that program as envisioned, those

ships may need wholesale changes in crewing concepts, watch standing, damage control, supervision,

training, and maintenance.

Even so, adopting the notional crewing approaches in Options IIA or IIB would require careful

planning and analysis. For example, the Navy might

want to try a pilot program using one or two submarines on each coast before committing to such alternative operating concepts for Virginia class submarines. However, the analysis of those options suggests that although carrying them out would require a

substantial departure from the way the Navy operates

attack submarines now, the dual- or multiple-crewing

concepts do not appear to be impossible, or even infeasible, to implement. Along with the other options,

they represent several ways to bridge the gap between the Navy’s actual or planned force structure

and its desired force structure 15 or 25 years from

now.

Appendixes

Appendix A

Determining the Size

of the Submarine Force

The Congressional Budget Office’s (CBO’s)

analysis of the attack submarine force is designed to address the force structure requirements posited in the 1999 study issued by the Chairman of the Joint Chiefs of Staff (CJCS). Those requirements are 68 attack submarines by 2015 and 76

attack submarines by 2025. The Navy endorsed that

study’s methodologies and shares the desire for more

attack submarines.

In making its own calculations of force structure

for this analysis, CBO employed the same methodology as the CJCS study. On the basis of submarine

deployments from 1995 through 1998, that study determined that the average 180-day deployment of an

attack submarine would comprise 77 days of operations (or mission days), 54 days of transit time, 27

days of maintenance, and 22 days of port visits.

From those numbers, the study developed the following formula to determine force structure requirements:

Force = (Op Rqmt/yr) * (6 mos/depl) * (TAR + 1) * 1 

Structure (Ops/Depl) (12 mos/yr) MF

where:

Op Rqmt/yr = number of days of operations requested per year

Ops/Depl = number of days of operations per

deployment (77)

TAR = turnaround ratio

MF = maintenance factor

The turnaround ratio is the time a submarine

spends in its home port relative to the time it spends

on deployment. (For example, if a submarine spends

18 months in its home port followed by a six-month

deployment, the turnaround ratio is 3.0.) Historically, Navy attack submarines have averaged a TAR

of between 2.8 and 3.0. The maintenance factor is

the amount of time an attack submarine will spend in

long-term, shipyard-level maintenance and thus removed from its deployment cycle.

According to that formula, one submarine with

a turnaround ratio of 2.8 and a maintenance factor of

0.88—the assumptions of the CJCS study—provides,

on average, 35.7 mission days per year over the

course of its 33-year service life. The study divided

the total number of mission days required by civilian

and military leaders by that figure to calculate the

necessary size of the attack submarine force. As the

formula makes clear, changing the estimates for the

number of mission days per deployment, the turnaround ratio, or the maintenance factor would yield

different results.

Appendix B

Estimating the Total Cost per

Mission Day and Cost per Additional

Mission Day Under Various Options

Akey measure that the Congressional Budget

Office (CBO) used to evaluate the cost-effectiveness of different options for attack submarines is the total cost of each mission day that a particular force of submarines would provide. To estimate that cost, CBO calculated the total costs for a

given option, including procurement, operation and

support, and any other costs, such as for infrastructure. It then annualized those costs, amortizing them

over the useful service life of the submarines to arrive at a steady-state level of spending that would be

required to sustain a given force indefinitely. That

number was then divided by the total number of mission days that the option would provide.

For example, a force of 100 attack submarines

would provide about 3,600 mission days per year (for

the source of that figure, see Appendix A). If those

submarines cost $2.1 billion apiece to build and had a

service life of 33 years, the annualized procurement

cost for those 100 submarines would be $6.4 billion

per year. If they each cost $33 million a year to operate, then 100 would cost $3.3 billion per year. Finally, if $10 million of additional infrastructure was

required to support those submarines and that infrastructure had an average service life of 50 years, then

the annual infrastructure cost of the force would be

$0.2 million per year. Thus, the total yearly cost for

the 100 submarines would be $9.7 billion. Dividing

that number by 3,600 yields a total cost of about $2.7

million for each mission day provided by that force.

CBO also calculated the cost of each mission

day that would be added to the force by a new attack

submarine based in the United States, a converted

Trident ballistic missile submarine, a Virginia class

submarine operated by more than one crew, and a

submarine based in Guam. Consider the following

example: a new submarine based in the United States

would have a service life of 33 years and cost $2.1

billion to build, CBO estimates. Its annual operating

cost would be $33 million, and it would provide

about 36 mission days per year. Thus, the cost per

additional mission day of building a new submarine

and basing it in the United States would be $2.7 million.

By comparison, a new submarine based permanently in Guam would also cost about $2.1 billion to

build but would have a service life of only about 27

years. Its annual operating cost would be $36 million

per year, CBO estimates. As discussed in Chapter 1,

it is assumed to provide 106 mission days per year,

on average. Consequently, the cost per additional

mission day that results from basing a new submarine

in Guam rather than the United States is:

[($2,100 million/27 years) + $36 million]

- [($2,100 million/33 years) + $33 million] = $0.24 million

 (106 mission days - 36 mission days)

In other words, the slightly higher annual cost of basing a submarine in Guam instead of the United States

(because of its shorter service life) is more than offset

by the greater number of mission days it provides.


This publication and others by CBO

are available at the agency's Web site:

www.cbo.gov