C L DUBEY – EXERCISE – 08 (DRY DOCKING)

Trim = 1009.23 ⨯ 88/300 ⨯ 100
= 2.960m by stern

20. A ship LBP 170m, displacement 21480 tonnes, KG 6.96m, KM 7.12m is being dry-docked. Calculate the maximum allowable stern trim to ensure stability is not negative when landing flat overall. TPC 30, MCTC 260, LCF 2m abaft of amidships.

Solution –

Old GM  =  (7.12 – 6.96)m
                 = 0.16m

GG₁ permissible = 0.16m
0.16 = P ⨯ 7.12/21480
P = 482.696 t

Now,  trim = P ⨯ d/ MCTC ⨯ 100
= 1.54m by stern

20. A ship length 200m, W 1400 tonnes is being docked at draughts 6.30m forward 7.60m aft LCF is 4m abaft of amidships. TPC 18, KM 8.80m. When just landing flat on the blocks the draught is 6.8m. Calculate the loss of GM.

Solution –

Correction to aft draft = 1.3 ⨯ 96/200
= 0.624m

Hd( hydrostatic draft)= 6.976m
Change in draft = rise = 0.176m
0.176 =      P/18 ⨯ 100
P = 316.8 tonnes