C L DUBEY – EXERCISE – 09 (GROUNDING)

Q1. A vessel of length 142m, displacement 16130t, KM 8.24m, KG 7.26m MCTC 192 mt, TPC 23.4t, LCF 71m, FSM 1372 mt, at a draft of F 6.70m, A 8.86m, ground on a rock. The draft then F 5.90m, A 9.30m.
Calculate :

1. The upthrust provided by the rock.

2. The position with respect to AP where the grounding occurred.

3. Her virtual GM (FI.) then

4. The rise of tide required for her to refloat.

Solution –

• Draft before Grounding = 6.70m, Aft = 8.86m

Trim = 2.16m
Correction to aft draft = 2.16 ⨯ 71/142
= 1.08m
∴ Hydrostatic draft = 7.78m

Draft after grounding = 5.90 m fwd

Trim = 3.4m
Correction to aft draft =   3.4 ⨯ 71/142
∴ Hydrostatic draft = 7.60m
Rise = P/ TPC ⨯ 100
P = (0.18 ⨯ 23.4 ⨯ 100)

   = 421.2 tonnes