Page 169 - statbility for masters and mates

Trim 157
EXERCISE 15
1 A ship of 8500 tonnes displacement has TPC 10 tonnes, MCT 1 cm 100 tonnesm and the centre of ¯otation is amidships. She is completing loading under coal tips. Nos. 2 and 3 holds are full, but space is available in No. 1 hold (centre of gravity 50 m forward of amidships), and in No. 4 hold (centre of gravity 45 m aft of amidships). The present drafts are 6.5 m F and 7m A, and the load draft is 7.1m. Find how much cargo is to be loaded in each of the end holds so as to put the ship down to the load draft and complete loading on an even keel.
2 An oil tanker 150 m long, displacement 12 500 tonnes, MCT 1 cm 200 tonnes m, leaves port with drafts 7.2 m F and 7.4 m A. There is 550 tonnes of fuel oil in the foward deep tank (centre of gravity 70 m forward of the centre of ¯otation) and 600 tonnes in the after deep tank (centre of gravity 60m aft of centre of ¯otation). The centre of ¯otation is 1m aft of amidships. During the sea passage 450 tonnes of oil is consumed from aft. Find how much oil must be transferred from the forward tank to the after tank if the ship is to arrive on an even keel.
3 A ship 100m long, and with a displacement of 2200 tonnes, has longitudinal metacentric height 150m. The present drafts are 5.2m F and 5.3m A. Centre of ¯otation is 3m aft of amidships. Find the new drafts if a weight of 5 tonnes already on board is shifted aft through a distance of 60 metres.
4 A ship is ¯oating at drafts of 6.1 metres F and 6.7 metres A. The following cargo is then loaded:
20 tonnes in a position whose centre of gravity is 30 metres forward of amidships.
45 tonnes in a position whose centre of gravity is 25 metres forward of amidships.
60 tonnes in a position whose centre of gravity is 15 metres aft of amidships.
30 tonnes in a position whose centre of gravity is 3 metres aft of amidships.
The centre of ¯otation is amidships, MCT 1cm 200 tonnesm, and
TPC 35 tonnes. Find the new drafts forward and aft.
5 A ship arrives in port trimmed 0.3 m by the stern and is to discharge 4600 tonnes of cargo from 4 holds. 1800 tonnes of the cargo is to be discharged from No. 2 and 800 tonnes from No. 3 hold. Centre of ¯otation is
amidships, MCT 1 cm 250 tonnes m.
The centre of gravity of No. 1 hold is 45 m forward of amidships. The centre of gravity of No. 2 hold is 25 m forward of amidships. The centre of gravity of No. 3 hold is 20 m aft of amidships.
The centre of gravity of No. 4 hold is 50 m aft of amidships.