C L DUBEY – EXERCISE – 08 (DRY DOCKING)

Therefore, New Virtual GM = (0.7 – 1.280)m
                                                       = -0.580m

3. A vessel is to be dry docked in a damaged condition. She is floating at F 12.60m and A 9.00m. it is estimated that she will take the blocks 15m aft of the forward perpendicular. Estimated data: KG 8.9m, KM 9.4m, TPC 21.3 t/cm, MCTC 290 tm/cm, AF 76m, LBP 165m displacement 19500 tonnes.

• Is it safe to dry dock the vessel in this condition? Support your answer with calculation.

• Estimate the drafts at the perpendiculars on taking to the blocks fore and aft.

Solution –

• Trim = 3.60m, d = 74m

P = (trim ⨯ MCTC)/d
= (360 ⨯ 290)/74
= 1410.8 tonnes

GG₁ = (P ⨯ KM)/W
= (1410.8 ⨯ 9.4)/19500
= 0.680m

Old GM = 0.5m,
GG₁ = 0.680m