887-B150-01_Damage Stability Rev(-)_signed.pdf

NSF McMurdo Offload Infrastructure 9 June 2023 Damage Stability Report 1 Doc. 887-B150-01, Rev -

NSF MCMURDO OFFLOAD INFRASTRUCTURE

Damage 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-B150-01

REV:

FILE:

22105.01

DATE:

9 June 2023

References

1. Glosten, ABS Design Methodology and Parameters, 887-B003-01.

2. International Maritime Organization (IMO), International Code for Ships Operating in Polar

Waters (Polar Code), 2017.

3. Glosten, Weight Estimate Report, 887-B115-01.

4. Glosten, 887_damaged_Rev(-).rf.

5. Glosten, General Arrangements & Inboard Profile, 887-B215-01.

6. ABS Steel Barge Rules, 2022.

7. International Maritime Organization, International Convention for the Safety of Life at Sea

(SOLAS), 2020.

8. 46 CFR § 172.D Special Rules Pertaining to a Vessel That Carries a Cargo Regulated Under

33 CFR Part 157, 2023.

9. Glosten, 887_Stability Summary.xlsx.

10. Glosten, 887_Damaged_Rev(-).pf.

Damage Stability Calculations

The barge-like floating pier subdivision was evaluated against a 2-compartment damage standard considering Polar Code damage requirements and found to be satisfactory (References 1, 2).

Damage stability was assessed across a range of displacements including each loading condition described in Reference 3.

Damage 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 drafts. These maximum allowable VCG curves are 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.

The minimum freeboards and deck slopes resulting from one- and two-compartment damage cases were calculated to assess the potential impact of damage on barge operations such as removing personnel or equipment from the barge after damage. The barge is expected to have a deck slope less than 4% without deck immersion after reaching damaged equilibrium for both one- and two-compartment damage cases.

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).

Damage Stability Report 2 Doc. 887-B150-01, Rev -

Subdivision

The collision bulkhead is located at 20’ aft of the forward perpendicular, at Frame 4. Main transverse watertight bulkheads are located at Frames 7, 13, 25, 37, 49, and 55. (see Reference

5). Bulkhead locations are aligned with the requirements of ABS Steel Barge Rules 3-2-6/3

(Reference 6). All compartments were considered to have a permeability of 0.95 as void spaces per SOLAS Chapter II-1, Part B-1 Regulation 7-3/1 (Reference 7).

Floodable lengths were assessed at the upper ice waterline (UIWL) for an even keel condition.

The margin line of the barge pier is located at the deck edge. As the vessel has no downflooding points (see Reference 5), this is a conservative assumption and is aligned with the requirements of 46 CFR 172.065(g)(1) (Reference 8).

The vessel subdivision was found to be satisfactory with respect to floodable lengths assuming a minimum GM1 of 0.25 ft (see Figure 1 below). Reference 4 includes the floodable length run file used in this analysis.

Figure 1 Barge floodable lengths at 8-ft UIWL, zero trim

1 A GM sensitivity study performed suggests that the floodable length is not dependent on the minimum GM for this barge and loading condition.

Damage Stability Report 3 Doc. 887-B150-01, Rev -

Damage Stability Criteria

The Polar Code, 3.3 (Reference 2) requires that the factor si be equal to one for probabilistic damage stability assessment following SOLAS Chapter II-1, Part B-1 (Reference 7).

As the barge pier is not a passenger vessel and does not have crossflooding devices, the factor si is calculated using the following formula:

𝑠𝑖 = 𝑠𝑓𝑖𝑛𝑎𝑙,𝑖 = 𝐾 × [

𝐺𝑍𝑚𝑎𝑥

𝑇𝐺𝑍𝑚𝑎𝑥

𝑅𝑎𝑛𝑔𝑒

𝑇𝑅𝑎𝑛𝑔𝑒

where: GZmax is the maximum positive righting arm up to the angle of downflooding, not to be taken as greater than TGZmax;

Range is the range of positive righting arms from the equilibrium heel angle to downflooding, not to be taken as greater than TRange;

TGZmax is 0.394 ft (0.12 m) for a cargo vessel;

TRange is 16° for a cargo vessel;

K = 1 only if the equilibrium heel angle is less than 25° for a cargo vessel.

The factor si is also set as zero if either downflooding or progressive flooding from damage may occur. Therefore, the barge pier will have a calculated factor si equal to one for any damage case where it meets all the following criteria:

• The maximum righting arm is not less than 0.394 ft (GZmax ≥ TGZmax)

• The range from the equilibrium heel angle to the angle of vanishing stability or downflooding is not less than 16° (Range ≥ TRange).

• The equilibrium heel angle is not more than 25° (𝐾 = 1).

• No downflooding or progressive flooding occurs after damage.

Damage Cases

Table 1 lists the damage cases considered in the damage stability analysis.

Table 1 Damage cases

Damage Cases Damaged

Compartments

1 1.C, 2.C

2 2.C, 3.C

3 3.C, 4.C

4 4.C, 5.C

5 5.C, 6.C

6 6.C, 7.C

7 7.C, 8.C

Maximum VCG Curves

The composite maximum allowable VCG curves for all damage cases and criteria are shown in

Figure 2 for a trim envelope including all operating conditions of the pier barge as described by

Reference 3. Damage cases 2 and 6 are the limiting cases for the full range of drafts. The results used to create these curves are included in References 9 and 10.

Damage Stability Report 4 Doc. 887-B150-01, Rev -

Figure 2 Maximum allowable VCG for damage stability criteria with load conditions plotted

The loading conditions pass all damage stability criteria. The barge trim does not have a substantial effect on its damage stability performance.

Damaged Hydrostatics

The conditions on deck resulting from damage during summer operations were calculated. The resulting minimum freeboards and deck slopes for all one- and two-compartment damage cases with initial conditions of an 8’ draft and 15’ VCG are shown in Table 2. A 15’ VCG is conservative compared to the five loading conditions. The edge of the deck is not immersed in any damage condition. The maximum deck slope is no more than 1.5% for 1-compartment damage cases and no more than 3.6% for 2-compartment damage cases.

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 6.5 7 7.5 8 8.5

M ax im u m V

C G ft

A B

L)

Draft (ft)

Governing MaxVCGs by Trim, Damage

Even keel

+/- 1ft trim

+/- 2ft trim

Load Cases

Does Not Meet Criteria

Meets Criteria

Damage Stability Report 5 Doc. 887-B150-01, Rev -

Table 2 Minimum freeboards and deck slope for 1- and 2-compartment damage

Damaged Compartment(s) Minimum Freeboard (ft) Maximum Trim (%)

1-Compartment Damage

1 9.69 0.2%

2 8.71 0.6%

3 6.90 1.4%

4 5.82 1.5%

5 8.24 0.1%

6 5.81 1.5%

7 6.90 1.4%

8 8.41 0.8%

2-Compartment Damage

1/2 8.40 0.8%

2/3 4.91 2.3%

3/4 0.67 3.6%

4/5 3.24 1.6%

5/6 3.24 1.6%

6/7 0.66 3.6%

7/8 2.70 3.4%