C L DUBEY – EXERCISE – 09 (GROUNDING)

Q7. A vessel of displacement 12200 t, MCTC = 200 tm, COF = 3 m, for’d of midship, length 152 m, KG = 7.2 m, KM = 8.1 m has draft for’d 5.1m, A 5.2 m. This vessel runs aground on an isolated rock 11.5 m aft of for’d perpendicular. Find the virtual Gm and Draft for’d and Aft. Given TPC = 25t, fall in tide 1 meter.

Solution –

W = 12200, distance from COF of grounding location = 61.5m

We can calculate fall in tide –

Fall in tide = P/ TPC + ( P x AL / MCTC) + AL/ LBP
100 = P/25 + P ⨯ 58/200 ⨯ 58/152
P = 608.21 tonnes.
GG₁ = (P ⨯ KM)/W
GG1 = 0.404
Virtual GM = 0.495m.

Rise = P/ TPC ⨯ 100
Rise = 0.243m

T_C = (P x D)/ MCTC
= (608.21x 58) /200
Tc = 1.870m,

We know that –
Ta = 0.972m,
Tf =   ( Tc – Ta)
= 0.898m