887-B155-01_Intact Stability Rev(-)_signed.pdf
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This intact stability report evaluates a floating pier barge proposed for the McMurdo Station in Antarctica under the intact stability criteria of the International Maritime Organization Code. The barge design was found to meet all intact stability requirements across the expected operating ranges of displacement and trim, including the righting arm curve properties, severe wind and rolling criteria for pontoons, and the recommended range of positive stability. The loading conditions analyzed included transit, summer, winter, and post-installation scenarios. The report provides intact stability calculation results and maximum allowable center of gravity curves plotted against these loading conditions. Damage stability criteria were also reviewed and found to be less restrictive than intact stability requirements. This design appears suitable to meet intact stability standards for the intended application of offloading infrastructure at McMurdo Station, Antarctica.
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NSF McMurdo Offload Infrastructure 9 June 2023 Intact Stability Report 1 Doc. 887-B155-01, Rev -
NSF MCMURDO OFFLOAD INFRASTRUCTURE
Intact Stability Report
PREPARED FOR:
Moffatt & Nichol
Seattle, WA
BY:
Calder J. Hartigan
NAVAL ARCHITECT
CHECKED:
Andrew L. Girdler, PE
NAVAL ARCHITECT
APPROVED:
Bradley G. Lamkin, PE
PRINCIPAL-IN-CHARGE
DOC. #:
887-B155-01
REV:
FILE:
22105.01
DATE:
9 June 2023
References
1. International Maritime Organization (IMO), International Code on Intact Stability, 2008.
2. Glosten, ABS Design Methodology and Parameters, 887-B003-01.
3. Glosten, Weight Estimate Report, 887-B115-01.
4. Glosten, 887_Intact_Rev(-).rf.
5. Glosten, General Arrangements & Inboard Profile, 887-B215-01.
6. Glosten, 887_Intact_Rev(-).pf.
7. Glosten, 887_Stability Summary.xlsx.
8. Glosten, Damage Stability Report, 887-B150-01.
Intact Stability Calculations
The barge-like floating pier was evaluated against the IMO Intact Stability Code (Reference 1) as prescribed by Reference 2 and found to be satisfactory. Intact stability was assessed across a range of displacements and trims including each loading condition described in Reference 3.
Intact stability results are summarized by plots of the maximum allowable vertical center of gravity as measured from the molded baseline (VCG) versus the full range of vessel operating displacements and trims. This maximum allowable VCG curve is the basis of evaluating the compliance of each loading condition with the stability criteria. The General Hydrostatics (GHS) run file used for this analysis is included in Reference 4.
Downflooding Points
No downflooding points are present. Raised bolted watertight hatches provide access to each void space, and no vents or other possible downflooding points are included in the design (see
Reference 5).
Intact Stability Criteria
The following stability criteria from the IMO Intact Stability Code (Reference 1) were assessed:
• Part A: Mandatory criteria o 2.2.2 Criteria regarding righting lever properties
▪ Modified with Explanatory Notes, 4.1: Criteria regarding righting lever curve properties (B/D > 2.5) o 2.2.3 Severe wind and rolling criterion (weather criterion)
• Part B: Recommendations for certain types of ships and additional guidelines o 2.2.4 Pontoons
▪ 2.2.4.1 Righting arm curve area
Intact Stability Report 2 Doc. 887-B155-01, Rev -
▪ 2.2.4.2 Steady wind heel
▪ 2.2.4.3 Range of positive stability
The resulting heeling moment of the wind pressure required by Part B, 2.2.4.2 was compared to the that of the winter and summer operational conditions. Table 1 summarizes the wind speed, corresponding pressure, exposed lateral area, lever arm, and resultant heeling moment for each condition. For the requirement of Part B, 2.2.4.2 and the winter condition, the lateral area and lever arm were based on the 6’ lowest draft in considered in the maximum VCG curves. The lateral area and lever arm for the summer condition were based on the force that would be produced by the largest vessel to be moored against the barge pier acting on the fenders of the barge pier. The worst case heeling moment was adopted for intents and purposes of this analysis or requirement.
Table 1 Steady Wind Heeling Moments
Condition Wind Speed
(kt)
Wind Pressure (LT/ft2)
Lateral Area (ft2)
Lever Arm (ft)
Heeling Moment (LT-ft)
IMO IS Code, Part B, 2.2.4.2 0.00503 7100 14.16 505.7
Winter condition 110.2 0.02257 7100 14.16 2270
Summer condition 55.3 0.00568 33383 12.46 2363
Maximum VCG Curves
The maximum allowable VCGs based on each set of stability criteria are shown in Figure 1 alongside the loading conditions described in Reference 3. The limiting maximum VCGs in a range of trims of +/- 2 ft are shown. The results used to create these curves are included in
References 6 and 7.
Figure 1 Maximum allowable VCG for intact stability criteria with load conditions plotted
TRANSIT
SUMMERWINTER
LIGHT INSTALLED
POST-DELIVERY
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
6 6.5 7 7.5 8 8.5
M ax im u m A llo w ab le
V C
G ft A
B L)
LCF Draft (ft)
Maximum VCG, Intact Stability
IMO ISC A 2.2.2
Righting Arm
IMO ISC A 2.2.3, Severe Wind & Roll
IMO ISC B 2.2.4.1
Pontoon RA Area
IMO ISC B 2.2.4.2
Pontoon Wind Heel
IMO ISC B 2.2.4.3
Pontoon Stability Range
Loading Conditions
Meets Criteria
Does Not Meet Criteria
Intact Stability Report 3 Doc. 887-B155-01, Rev -
The loading conditions pass all intact stability criteria. The severe wind and rolling criteria are only applicable to the transit load case, for which they are the governing criteria. The summer, winter, and lower ice waterline loading conditions are governed by the righting arm criteria of
Part A, 2.2.2. As the barge will be restrained when moored in Winter Quarters Bay, this result is expected to be conservative.
The intact stability criteria are more limiting than the damage stability criteria described in
Reference 8, shown by the composite maximum allowable VCG curve in Figure 2.
Figure 2 Composite maximum VCG for +/- 2 ft trim, intact and damage stability criteria
TRANSIT
SUMMER
WINTER
LIGHT INSTALLED POST-DELIVERY
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
6.5 6.75 7 7.25 7.5 7.75 8 8.25 8.5
M ax im u m V
C G ft
A B
L)
Draft (ft)
Composite Maximum VCG
Intact Governing
Damage Governing
Load Cases
| 2023-06-09T15:23:55-0700 | |
| Andrew Girdler |
File details come from the government source that posted it. Updated .