To: Chris Diez

From: William Shute

Date: October 12, 2006

Subject: DCAESG100 -- Results of Static OPTIMOOR Mooring Analyses and
Passing Vessel Interaction Study

------------------------------------------------------------------------------------------------------------

**Introduction**

HPA has completed static mooring analyses for Pier 1 of the proposed
Sparrows Point LNG Terminal. The objectives of these analyses are to
confirm the adequacy of the mooring hardware and fendering arrangement
by ensuring that the calculated mooring line loads, vessel motions while
moored, and fender breasting forces are within allowable limits.

OPTIMOOR, Version 4.8.8 was utilized to complete the analyses. This
program calculates line tensions, fender loads, ships motions, and
bollard forces, based on user inputs including ship geometry, mooring
arrangement, fender and line properties, and wind and current speeds.
Wave forces were not accounted for in these static analyses. A dynamic
mooring analysis, which includes the effects of wave action, is beyond
the scope of this evaluation.

In addition, calculations have been performed to assess the potential
impact of passing ships in Brewerton Channel on moored LNG tankers at
the proposed Sparrows Point LNG Terminal. The results demonstrate that
the hydrodynamic loads caused by passing ships are less than the
environmental loads from winds and currents, and are not problematic for
moored ships at the terminal. This outcome is due to the large
separation distance between the Brewerton Channel and the proposed LNG
Terminal.

**Mooring Analysis Input Parameters**

In order to conduct the mooring analyses, the following information is
required to be input into the OPTIMOOR Program:

-   Facility layout as shown in Figure 1, including locations of fenders
    and mooring hooks relative to the ship manifold

-   Design LNG vessel data

-   Environmental data

> This information is discussed further in the following sections.

*[Facility Layout]{.underline}*

Figure 1 illustrates the LNG marine terminal layout. The arrangement
utilizes the existing Pier 1, and includes two berths: one to the north
of the pier and one to the south of the pier. Quadruple quick release
hooks, with 150 tonne capacity per hook are assumed for the bow and
stern mooring lines, while triple quick release hooks, also with 150
tonne capacity hook are assumed for the spring lines. Each berth also
has six foam-filled fenders installed along its length.

*[Design LNGC Vessel Data]{.underline}*

Three design vessels were evaluated in this analysis: LNGC4, LNGC7, and
LNGC10. Table 1 lists the vessel data required for input into the
mooring analysis software. These three vessels were selected as they
best characterize the range of design vessels established for the
proposed LNG Terminal. More specifically, LNGC4 was selected to
represent the smaller vessels that may call at the LNG Terminal, whereas
LNGC7 and LNGC10 were selected to represent the largest vessels that may
call at the LNG Terminal.

The ships were modeled with a conventional bow and have the capability
of utilizing up to 16 mooring lines in a 6-2-2-6 (bow - forward spring -
aft spring - stern) arrangement. Chock locations for ships lines were
based on currently available LNGC arrangement data.

*[Design LNGC Environmental Data]{.underline}*

Table 2 summarizes the environmental data utilized in the analysis.

The 45 foot water depth was established for the conceptual design for
the channel and basins, and is based on a vessel with a static loaded
draft in the order of 40.5 feet; the deepest draft of the vessels
expected to call at the proposed LNG Terminal.

![](media/image1.png){width="6.047916666666667in"
height="7.840277777777778in"}

Fig 1 -- LNG Marine Terminal Layout

> Table 1 -- Vessel Data

  ----------------- ----------------- ----------------- -----------------
  Ship              LNGC4             LNGC7             LNGC10

  LBP (ft)          872.7             1046.6            994.1

  Draft (ft)        30.8              33.8              32.8

  Depth (ft)        85.3              90.2              88.6

  Beam (ft)         142.4             158.1             164.1

  Manifold Offset   +10.5             -35.8             0.0
  from Midship\                                         
  (+ = Forward of                                       
  Midship)                                              

  Windage Area --   13,693            19,117\*          19,377
  Longitudinal (sq                                      
  ft)                                                   

  Windage Area --   64,342            91,028\*          90,964
  Lateral (sq ft)                                       

  Line Type         44mm Steel Wire\* 44mm Steel Wire\* 44mm Steel Wire\*

  Line Breaking     128               128               128
  Strength (tonnes)                                     
  ----------------- ----------------- ----------------- -----------------

\* estimated

> **Table 2 -- Environmental Data**

  ----------------------------------- -----------------------------------
  Water Depth                         45 ft

  Wind Speed                          45 knots all directions

  Current                             0.3 knots perpendicular to berth
  ----------------------------------- -----------------------------------

In order to determine the appropriate wind velocity to be used in the
analyses, HPA reviewed the standard operating procedures for many marine
terminals, and found that typically the maximum allowable wind speed at
which a vessel can remain at berth is approximately 50 mph (43.4 knots).
HPA then reviewed available field data from multiple sources in the
vicinity of the proposed LNG Terminal in order to ensure that such wind
velocity is reasonable for this specific location. Based on long-term
wind information collected at Baltimore-Washington International
Airport, as well as from wind data collected from a NOAA owned and
operated station at Thomas Point, and from a Chesapeake Bay Observing
System wind station near the Chesapeake Bay Bridge, maximum recorded
wind speeds are in the range of 30 knots, with a maximum recorded gust
of 56.5 knots. This data confirms that the selection of an operational
wind speed of 45 knots is a conservative, yet appropriate, value for the
mooring analyses.

A current of 0.3 knots was applied perpendicular to the berth. As part
of an associated task, HPA has completed a hydrodynamic model that
concludes that the currents in the vicinity of the proposed LNG terminal
are primarily tidal-driven and are estimated to have maximum velocities
that approach approximately 0.1 knots. A current of 0.3 knots is
considered conservative, but appropriate, for use for this type of
evaluation as it provides a factor of safety for localized currents and
extreme environmental conditions.

**Mooring Analysis Evaluation Criteria**

As previously mentioned, in order to confirm the adequacy of the mooring
hardware and fendering arrangement, this evaluation assesses the
adequacy of calculated mooring line loads, vessel motions while moored,
and fender breasting forces. The following criteria have been
established for comparison to the calculated results in order to
evaluate the overall mooring arrangement:

*[Allowable Mooring Line Loads]{.underline}*

LNGC vessels commonly utilize 44 millimeter (mm) diameter steel wire
lines with a breaking strength of 128 tonnes. Oil Companies
International Marine Forum Mooring Equipment Guidelines (1997) recommend
that the maximum allowable line tension is limited to 55 percent of the
line breaking strength. As a result, the maximum allowable line tension
established for this evaluation is 70.4 tonnes (155.2 kips). Line loads
less that 70.4 tonnes, as calculated by OPTIMOOR, are considered
acceptable.

*[Vessel Motions]{.underline}*

Vessel motion criteria recommended by the International Navigation
Association (PIANC) "Criteria for Movements of Moored Ships in Harbors
Guidelines" (1995) were adopted. The PIANC allowable maximum vessel
motions for safe loading and unloading of moored LNG vessels are
provided in Table 3. For the static mooring analysis, OPTIMOOR
calculates the maximum target motions for surge, sway, and yaw due to
current and wind forces.

**Table 3 -- Allowable Vessel Motions**

  ----------------------- ----------------------- -----------------------
  Surge (ft)              Sway (ft)               Yaw (°)

  6.4                     6.4                     2
  ----------------------- ----------------------- -----------------------

*[Breasting Forces]{.underline}*

OPTIMOOR determines the load on the fenders resulting from the
environmental forces that act to press the LNGC against the berth
fenders. These breasting forces are compared to rated reaction of the
fender. For this analysis, a 2 meter (m) diameter by 3 m long foam
filled fender was assumed. This specific fender has a maximum allowable
rated reaction equal to 209 kips. The fender is deemed adequate if the
fender thrusts, as calculated by OPTIMOOR, are less than 209 kips.

**Mooring Analysis Results**

A total of six OPTIMOOR runs were completed; one run for each of the
three vessels in both the north and south berths. Figures 2 -- 7
illustrate the mooring configurations which were evaluated. Table 4
provides a summary of model results and compares them to the acceptable
criteria.

![](media/image3.png){width="5.7652777777777775in"
height="3.095833333333333in"}

Fig 2 -- LNGC4 North Berth Arrangement

![](media/image4.png){width="5.7652777777777775in"
height="3.095833333333333in"}

Fig 3 -- LNGC4 South Berth Arrangement

![](media/image5.png){width="5.7652777777777775in"
height="3.095833333333333in"}

Fig 4 -- LNGC7 North Berth Arrangement

![](media/image6.png){width="5.7652777777777775in"
height="3.095833333333333in"}

Fig 5 -- LNGC7 South Berth Arrangement

![](media/image7.png){width="5.7652777777777775in"
height="3.095833333333333in"}

Fig 6 -- LNGC10 North Berth Arrangement

![](media/image8.png){width="5.7652777777777775in"
height="3.095833333333333in"}

Fig 7 -- LNGC10 South Berth Arrangement

**Table 4 -- Summary of Results**

  ---------- ---------- ----------- ---------- ----------- ----------- -----------
  Model Run  Maximum    Allowable   Maximum    Allowable   Maximum     Allowable
             Line Load\ Line Load\  Vessel     Vessel      Breasting   Breasting
             (kips)     (kips)      Motions\   Motion\     Force\      Force\
                                    (ft, ft,   (ft, ft,    (kip)       (kip)
                                    deg)       deg)                    

  LNGC4      145.6      155.2       Surge 0.8\ Surge 6.4\  135         209
  North                             Sway 1.9\  Sway 6.4\               
  Berth                             Yaw 0.2    Yaw 2.0                 

  LNGC4      138.8      155.2       Surge 0.6\ Surge 6.4\  136         209
  South                             Sway 1.9\  Sway 6.4\               
  Berth                             Yaw 0.2    Yaw 2.0                 

  LNGC7      140.8      155.2       Surge 0.6\ Surge 6.4\  164         209
  North                             Sway 2.2\  Sway 6.4\               
  Berth                             Yaw 0.2    Yaw 2.0                 

  LNGC7      120.7      155.2       Surge 0.6\ Surge 6.4\  168         209
  South                             Sway 2.2\  Sway 6.4\               
  Berth                             Yaw 0.2    Yaw 2.0                 

  LNGC10     146.7      155.2       Surge 0.6\ Surge 6.4\  181         209
  North                             Sway 2.3\  Sway 6.4\               
  Berth                             Yaw 0.3    Yaw 2.0                 

  LNGC10     134.8      155.2       Surge 0.7\ Surge 6.4\  187         209
  South                             Sway 2.3\  Sway 6.4\               
  Berth                             Yaw 0.3    Yaw 2.0                 
  ---------- ---------- ----------- ---------- ----------- ----------- -----------

**Passing Vessel Interaction Analysis**

Calculations have been performed to assess the potential hydrodynamic
impacts of passing ship traffic in Brewerton Channel on moored LNG
tankers at the Sparrow's Point LNG Terminal. The analysis is based on
the PASS-MOOR spreadsheet program (Ref. 1), modified by the results of
comprehensive physical hydraulic model tests performed by the US Navy
(Ref. 2). The calculations are based on an assumed transit speed of 7
knots for large vessels transiting the project area ("Brewerton Angle"),
determined from discussions with the Association of Maryland Pilots.

The analysis includes several scenarios for passing ships and moored LNG
tankers, including the largest vessels that transit this channel (bulk
carriers and cruise ships in the range of 90,000 DWT). The results
demonstrate that due to the large distance from the channel, the
hydrodynamic loads caused by passing ships are less than the loads for
the operational environmental conditions, and are not considered
problematic for moored ships at the proposed LNG Terminal. Typical
results are presented in the following figures, which give time series
for the global forces on the moored LNG tanker with the passage of large
ship in Brewerton Channel. Figure 8 shows the surge forces (Fx) and sway
forces (Fy) on the ship, and Figure 9 gives the corresponding yaw
moments.

![](media/image9.wmf){width="5.997916666666667in"
height="3.4180555555555556in"}

Fig 8 -- Global Surge and Sway Force Time Series from Passing Ship

![](media/image10.wmf){width="5.997916666666667in"
height="3.4180555555555556in"}

Fig 9 -- Global Yaw Moment Time Series from Passing Ship

**Conclusions**

Based on the results of the OPTIMOOR analyses, the proposed mooring and
fendering arrangement on Pier 1 is adequate for the mooring of the
proposed design LNG vessels. More specifically, all line loads, vessel
motions, and breasting loads are within acceptable limits as defined for
the criteria evaluated.

Based on the results of the PASS-MOOR analysis for passing ship effects
it is concluded passing ships in Brewerton Channel will not adversely
affect moored LNG tankers at the Sparrow's Point LNG Terminal. The
design basis environmental loads due to wind and current are much larger
than the transient loads due to passing vessels. Because these larger
loads are shown to be within acceptable limits based on the OPTIMOOR
analyses, the smaller loads associated with passing vessel traffic are
also within acceptable limits.

**References:**

1\. Seelig, "Passing Ship Effects on Moored Ships," Technical Memorandum
TM-6027-OCN, Naval Facilities Service Center, 2001.

2\. Kriebel, Seelig and Eskijian, "Mooring Loads due to Paralleel
Passing Ships," Technical Report TR-6056-OCN, Naval Facilities Service
Center, 2005.