1

Regulatory

Update

Office of Transportation

and Air Quality

EPA420-F-04-031

August 2004

Overview of EPA’s Emission

Standards for Marine Engines

The U.S. Environmental Protection Agency’s (EPA) emission control

program for marine engines consists of several sets of standards which

vary based on the type of engine (gasoline or diesel powered) and

engine size. These standards apply to newly manufactured products

produced after the effective date of the standards.

This fact sheet gives an overview of the final and proposed rules for

marine engines and vessels as of July 2004. Refer to our Web site for

additional information about the standards and the certification and

compliance programs, as well as for regulatory updates.

What are the compression-ignition (diesel) marine

engine standards?

Marine diesel engines are grouped into the five categories shown in

Table 1. Each of these are subject to different standards.

Acronyms Used in This Fact Sheet

kW = kilowatts

g/kW-hr = grams per kilowatt-hour

rpm = revolutions per minute

HC + NOx = hydrocarbons plus nitrogen oxides

PM = particulate matter

CO = carbon monoxide
2

Table 1: Marine Diesel Engine Categories

Small Marine Diesel Engines (<37 kW)

Small marine diesel engines were included in our Tier 1 and Tier 2 nonroad diesel engine

rules and are subject to the same emission limits as their land-based counterparts, as

shown in Table 2.

Table 2: Small Marine Diesel Enginesa

See: www.epa.gov/nonroad-diesel

a

 The emission limits are set out in Tables 6 and 7.

Category 1 Commercial and Category 2 Marine Diesel Engines

Category 1 marine diesel engines are similar to land-based nonroad diesel engines. Most

Category 2 marine diesel engines are similar to locomotive engines.

The Tier 1 standards for these engines are equivalent to the nitrogen oxides (NOx) limits

adopted by the Annex VI to the International Convention on the Prevention of Pollution

from Ships, 1973, as Modified by the Protocol of 1978 Relating Thereto (this convention

T g ier R R ulemakin CF Effective

Dates

Tier 1

Control of Emissions of Air Pollution from Nonroad

Diesel Engines (published October 23, 1998, 63 FR

56968)

40 CFR 89

1999 or 2000,

depending on

engine size

Tier 2

2004 or 2005,

depending on

engine size

C r ategory R r ated Powe D n isplacement per Cylinde Final Rule Publicatio

S W mall < y 37 k a 8 n 199

Commercial C1

m37 kW

<5 liters

1999

C2 m5 liters and < 30 liters

C3 m3 3 0 liters 200

Recreational C1 m3 s 7 kW < 2 5 liter 200
3

is also known as MARPOL 73/78).1 The Annex VI standards apply to engines over 130

kW installed on vessels constructed on or after January 1, 2000, or engines that undergo

a major conversion on or after January 1, 2000. However, those standards are not enforceable until the Annex goes into effect in May 2005.2

 In the meantime, we adopted

these standards into our federal emission control program as Tier 1 standards. The Tier 1

standards are voluntary for all Category 1 and Category 2 engines through 2003. Beginning in 2004, they will be mandatory for engines m2.5 l/cyl installed on U.S. vessels. For

all engines subject to the Tier 1 standards, EPA's Tier 2 standards supersede the Annex

VI limits by 2007 (or 2009 for recreational engines above 2.5 l/cyl).

Table 3: Category 1 (Commercial only) and Category 2 Marine Diesel Enginesa

See: www.epa.gov/otaq/marine.htm

a The emission limits are set out in Tables 6 and 7.

b

 MARPOL Annex VI applies these standards to any engine >130 kW installed on a vessel constructed

on or after 1/1/2000 and any engine that undergoes a major conversion on or after 1/1/2000. However,

those requirements are not enforceable until the Annex goes into effect in May 2005. Annex VI limits are

superseded by the Tier 2 standards for these engines.

Category 3 Marine Diesel Engines

Category 3 marine diesel engines are very large engines used for propulsion power on

ocean-going vessels. The EPA standards for these engines are equivalent to the Annex

VI standards.

T g ier R R ulemakin C s F Effective Date

Tier 1

Control of Emissions from New Marine

Compression-Ignition Engines at or

Above 30 Liters per Cylinder

(published February 28, 2003, 68 FR

9746)

40 CFR 94

Voluntary

through 2003;

mandatory for

engines m2.5

l/cyl beginning

in 2004b

Tier 2

Control of Emissions of Air Pollution

from New Marine Compression-Ignition

Engines at or Above 37 kW (published

December 29, 1999, 64 FR 73300)

2004 to 2007,

depending on

engine size

1 Copies of the conference versions of the Annex and the NOx Technical Code can be found in Docket A97-50, Document II.B.01 or at www.epa.gov/otaq/marine.htm. Copies of the updated versions can be

obtained from the International Maritime Organization (www.imo.org).

2 The IMO Web site, www.imo.org, contains the latest information on the status of this convention.
4

Table 4: Category 3 Marine Diesel Enginesa

See www.epa.gov/otaq/marine.htm

a

 The emission limits are set out in Tables 6 and 7.

b

 MARPOL Annex VI applies these standards to any engine >130 kW installed on a vessel constructed on

or after 1/1/2000 and any engine that undergoes a major conversion on or after 1/1/2000. However, those

requirements are not enforceable until the Annex goes into effect in May 2005.

Recreational Marine Diesel Engines

Recreational marine diesel engines are those that will be installed on vessels used for

recreational purposes. They must be at or above 37 kW and less than 5 liters per cylinder

displacement to be considered recreational for the purposes of our standards. The Tier 1

standards for engines m2.5 liters/cylinder displacement are equivalent to the MARPOL

standards (described above). Once the MARPOL standards take effect, they will apply to

recreational engines >130 kW. The more stringent Tier 2 standards will supersede the

Tier 1 and MARPOL NOx limits.

Table 5: Recreational Marine Diesel Enginesa

See www.epa.gov/otaq/marine.htm

a

 The emission limits are set out in Tables 6 and 7.

b

 MARPOL Annex VI applies these standards to any engine >130 kW installed on a vessel constructed on or after

1/1/2000 and any engine that undergoes a major conversion on or after 1/1/2000. However, those requirements are

not enforceable until the Annex goes into effect in May 2005. Annex VI limits are superseded by the Tier 2

standards for these engines.

T g ier R R ulemakin C s F Effective Date

Tier 1

Control of Emissions from

New Marine CompressionIgnition Engines at or Above

30 Liters per Cylinder

(published February 28,

2003, 68 FR 9746)

40 CFR 94

Voluntary

through 2003;

mandatory

2004b

T g ier R R ulemakin CF Effective

Dates

Tier 1

Control of Emissions from New Marine

Compression-Ignition Engines at or

Above 30 Liters per Cylinder

(published February 28, 2003, 68 FR

9746)

40 CFR 94

Voluntary

through 2003;

mandatory for

engines m2.5

l/cyl beginning

in 2004b

Tier 2

Control of Emissions from Nonroad

Large Spark-Ignition Engines, and

Recreational Engines (Marine and

Land-Based) (published November 8,

2002, 67 FR 68242)

2006 to 2009,

depending on

engine size
5

Tables 6 and 7 present the emission standards for marine diesel engines. These standards

are for hydrocarbons (HC), oxides of nitrogen (NOx), and particulate matter (PM) and

are expressed in units of grams per kilowatt-hour (g/kW-hr).

Table 6: Tier 1 Standards for Marine Diesel Engines

a

 These standards are voluntary for all engines through 2003; they are mandatory for engines m2.5 l/cyl

beginning in 2004. For Category 1 and Category 2 engines, they will remain mandatory through 2006;

beginning in 2007 for commercial and 2009 for recreational, EPA standards supersede the Annex VI

limits for these engines.

Table 7: Tier 2 Standards for Marine Diesel Engines

a

 There are no Tier 2 standards for Category 3 marine engines.

Category

Power (kW) &

Displacement

(liter/cylinder)

Speed (rpm)

Tier 1

Model

Year

NOx

(g/kW-hr)

HC+NOx

(g/kW-hr)

PM

(g/kW-hr)

CO

(g/kW-hr)

Small

<8 kW

8[ kW <19

19[ kW <37

-

-

-

2000

2000

1999

-

-

-

10.5

9.5

9.5

1.0

0.8

0.8

8.0

6.6

5.5

1, 2, 3,

including

Recreational

m37 kW &

m2.5 l/cyl

a

rpm m2000

130[ rpm <2000

rpm<130

2004

2004

2004

9.8

45 x rpm-0.2

17

-

-

-

-

-

-

Categorya Displacement

(liter/cylinder) Power (kW)

Tier 2

Model

Year

HC+NOx

(g/kW-hr)

PM

(g/kW-hr)

CO

(g/kW-hr)

Small

-

-

-

<8 kW

8[ kW <19

19[ kW <37

2005

2005

2004

7.5

7.5

7.5

0.80

0.80

0.60

8.0

6.6

5.5

Commercial C1

disp. <0.9

0.9[ disp. <1.2

1.2[ disp. <2.5

2.5[ disp. <5.0

m37kW

-

-

-

2005

2004

2004

2007

7.5

7.2

7.2

7.2

0.40

0.30

0.20

0.20

5.0

5.0

5.0

5.0

C2

5.0[ disp. <15

15[ disp. <20

15[ disp. <20

20[ disp. <25

25[ disp. <30

-

<3300kW

m3300kW

-

-

2007

2007

2007

2007

2007

7.8

8.7

9.8

9.8

11.0

0.27

0.50

0.50

0.50

0.50

5.0

5.0

5.0

5.0

5.0

Recreational C1

disp. <0.9

0.9[ disp. <1.2

1.2[ disp. <2.5

2.5[ disp. <5.0

m37kW

m37kW

m37kW

m37kW

2007

2006

2006

2009

7.5

7.2

7.2

7.2

0.40

0.30

0.20

0.20

5.0

5.0

5.0

5.0
6

What emissions standards apply to spark-ignition (gasoline)

marine engines?

We also have several sets of standards for gasoline marine engines. For these engines we

distinguish between:

• Outboards and personal watercraft

• Sterndrive and inboard engines

• Gasoline auxiliary engines

Outboards and Personal Watercraft Exhaust Standards

The outboard and personal watercraft exhaust standards phase in over nine years from

1998 to 2006. Because it is an averaging standard,3

 manufacturers are typically offering a

mix of new and old technology throughout the phase-in period. The standard is based on

a curve function that is intended to represent the relationship between rated power and

brake-specific emissions. In addition, California has two additional tiers of standards that

are more stringent than the EPA standards (see www.arb.ca.gov).

Table 8: Outboard and Personal Watercraft Standardsa

See www.epa.gov/otaq/marinesi.htm

a

 The emission limits are set out in Table 11 below.

Gasoline Sterndrive and Inboard Engines

There are currently no federal standards for gasoline sterndrive and inboard engines.

However, we gave notice of our intent to develop emission standards for these engines

(published August 14, 2002, 67 FR 53050, see www.epa.gov/otaq/marinesi.htm). Although there are no federal requirements for these engines, California has adopted exhaust emission standards (see: www.arb.ca.gov).

3 This means that emission credits may be earned for engines certified below the emission standard. These

credits may be used to sell engines certified above the standard provided that, on average, the engines

meet the emission standard.

T g ier R R ulemakin C e F Effective Dat

1

Final Rule for New Gasoline Spark-Ignition

Marine Engines; Exemptions for New Nonroad

Compression-Ignition Engines at or Above 37

Kilowatts and New Nonroad Spark-Ignition

Engines at or below 19 Kilowatts (published

October 4, 1996, 61 FR 52088)

40 CFR 91

1998 to 2006;

standard becomes

more stringent over

time
7

Marine Generators

Gasoline auxiliary engines used onboard marine vessels are covered in our gasoline

nonroad engine programs. There are two sets of EPA standards for these engines which

are covered in our programs for land-based spark-ignition engines, as shown in Tables 9

and 10.

Table 9: Spark-Ignition Marine Generators <19 kWa

See www.epa.gov/otaq/equip-ld.htm

a

 The emission limits are set out in Table 12 below.

Table 10: Spark-Ignition Marine Generators >19 kWa

See www.epa.gov/otaq/largesi.htm

a

 The emission limits are set out in Table 13 below.

T g ier R R ulemakin C s F Effective Date

Tier 1

Emission Standards for New Nonroad

Spark-Ignition Engines at or Below 19

Kilowatts (published July 3, 1995, 60 FR

34581)

Revised Carbon Monoxide (CO) Standard

for Class I and II Nonhandheld New

Nonroad Phase 1 Small Spark-Ignition

Engines (published November 13, 1996,

61 FR 58296)

40 CFR 90

1997

Tier 2

Phase 2 Emission Standards for New

Nonroad Spark-Ignition Nonhandheld

Engines at or below 19 Kilowatts

(published March 30, 1999, 64 FR 15208)

2001 to 2007,

depending on

engine size

T g ier R R ulemakin C s F Effective Date

Tier 1

Control of Emissions from Nonroad

Large Spark-Ignition Engines, and

Recreational Engines (Marine and

Land-Based) (published November 8,

2002, 67 FR 68242)

40 CFR 1048

2004

Tier 2 2007
8

Table 11: Standards for Outboard and Personal Watercraft Spark-Ignition Marine Engines

a For engines over 4.3 kW, the emission standard is a function of rated engine power (P), in

Kilowatts.

Table 12: Standards for Spark-Ignition Marine Generators [19kW

a

 Zero hour standards (no deterioration considered in standards).

b

 Effective date. (If a new engine family is introduced after August 1, 2003, it must meet the

Phase 2 standards.)

Model

Year

HC+NOx (g/kW-hr)

< W 4.3 kW >4.3 k a

1 8 998 2 P 7 0.917x(151 + 557/ 0.9)+2.44

1 3 999 2 P 5 0.833x(151 + 557/ 0.9

)+2.89

2 8 000 2 P 2 0.750x(151 + 557/ 0.9

)+3.33

2 4 001 2 P 0 0.667x(151 + 557/ 0.9

)+3.78

2 9 002 1 P 7 0.583x(151 + 557/ 0.9

)+4.22

2 5 003 1 P 5 0.500x(151 + 557/ 0.9

)+4.67

2 0 004 1 P 3 0.417x(151 + 557/ 0.9

)+5.11

2 5 005 1 P 0 0.333x(151 + 557/ 0.9

)+5.56

2 1 006 8 P 0.250x(151 + 557/ 0.9

)+6.00

P s hase C t las Total Displacemen

(cubic centimeters)

M x odel Year HC+NO

(g/kW-hr)

CO

(g/kW-hr)

Phase 1 a I 5 c 7 c <22 1 1 99 1 9 6. 51

I c I c m2 7 25 1 4 99 1 9 3. 51

Phase 2

I 6 -A c 1 c <6 2 0 00 5 0 61

I 6 -B 6 [ c 1 c <100 2 0 00 4 0 61

I 0 10 [ c 7 c <225 August 200 b 1 0 6.1 61

I c I c m0 1 .225 200

2002

2003

2004

2005

18.0

16.6

15.0

13.6

12.1

610
9

Table 13: Standards for Spark-Ignition Marine Generators >19kW a

 Alternatively, can meet standard of (HC+NOx) × CO0.784 [8.57 g/kW-hr.

How can I get more information?

You can access documents on marine engine emission standards from EPA’s main nonroad engines, equipment, and vehicles Web page at:

www.epa.gov/nonroad

You can also contact the OTAQ library for document information at:

U.S. Environmental Protection Agency

Office of Transportation and Air Quality Library

2000 Traverwood Drive

Ann Arbor, MI 48105

(734) 214-4311 & 214-4434

E-mail: Group_AALibrary@epa.gov

T r ier M x odel Yea HC+NO

(g/kW-hr)

CO

(g/kW-hr)

1 4 2 0 00 4 0 . 5

2a 2 7 007 2 4 . 4.