New GM = -0.18m
Since GM is –ve it is not safe to dry dock vessel in this condition.
- Trim caused = Tc = (1410.8 ⨯ 74/290 ⨯ 100)
= 3.600m
Change in draft aft = 3.60 ⨯ 76/165
= 1.658m
Change in draft fwd = 1.942m
Mean rise = (1410.8/21.3 ⨯ 100)
= 0.662m
| Fwd | Aft | |
| Draft | 12.60m | 9.00m |
| -0.662m | -0.662m | |
| 11.938m | 8.338m | |
| -1.942m | +1.658m | |
| 9.996m | 9.996m |
Method 2 =
Corn to aft draft = (3.6 ⨯ 76)/165
= 1.658m
Hydrostatic draft = 10.658m,
Mean rise = 0.662m
Final draft fwd and aft = (10.658 – 0.662)
= 9.996m
-
A vessel, displacement 9013t, KG 8.0m, TPC 21.89, MCTC 162.7 tm, AF 72.013m, FSM 900 tm, enters a SW drydock drawing 3.4m fwd and 5.8m Aft. Find the virtual GM when the level of water has fallen one metre after the stem has taken to the blocks, the KM then being 9.151m. LBP = 145 m.
Solution –
Clearly stern will take block once level of water reaches 5.8m. i.e equal to aft draft present level = 4.8m
Corn to aft draft = Trim ⨯ LCF/LBP
= 2.4 ⨯ 72.013/145
= 1.192m
Hydrostatic draft = 4.608 m
Since present level of water is greater than hd ship has not taken block overall.
Reduction in aft draft = 100cm
Or, 100 = P/21.89 + (P ⨯ 72.013/162.7) ⨯ 72.013/145
Or, P1 = 376.64 tonnes
GG1 = P ⨯ KM/W
= 0.382m
Old GM = 1.151m, FSC = 900/(2013 – 376.64)
= 0.104m,
