• Author / Uploaded
• Graham Westbrook

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Examples

Example 1 A ship displaces 5000 t and has an initial KG of 4.5 m. Calculate the final KG if a weight of 20 t is moved vertically upwards from the lower hold (Kg 2.0 m) to the upper deck (Kg 6.5 m).

Example 2 A ship displaces 12500 t and has an initial KG of 6.5 m. Calculate the final KG if 1000 t of cargo is loaded into the lower hold at Kg 3.0 m.

Example 3 A ship has a displacement of 13400 t and an initial KG of 4.22 m. 320 t of deck cargo is discharged from a position Kg 7.14 m. Calculate the final KG of the ship.

Example 4 A ship displaces 10000 t and has a KG of 4.5 m. The following cargo is worked: Load: 120 t at Kg 6.0 m; 730 t at Kg 3.2 m. Discharge: 68 t from Kg 2.0 m; 100 t from Kg 6.2 m. Shift: 86 t from Kg 2.2 m to Calculate the final KG.

Kg 6.0 m.

Example 5 Prove that the KM of a box-shaped vessel changes with draught as shown below for the range of draughts 1.00 m to 15.00 m given that length is 100 m and breadth is 20 m.

From the values calculated it is seen that as draught increases, KM reduces to a minimum value and then starts to increase again.

Example 6 A box-shaped vessel has length 20 m and breadth 6 m. Calculate: (a) the moment of inertia for all the axis’ of rotation shown; (b) the moment of inertia about the two axis’ passing through the centre of flotation using the parallel axis’ theorem.

Example 7 A ship of 6000 tonnes displacement has KM 7.3 m and KG 6.7 m, and is floating upright. A weight of 60 tonnes already on board is shifted 12 m transversely. Find the resultant list.

Example 8 A ship of 8000 tonnes displacement has a GM 0.5 m. A quantity of grain in the hold, estimated at 80 tonnes, shifts and, as a result, the centre of gravity of this grain moves 6.1 m horizontally and 1.5 m vertically. Find the resultant list.

Example 9

A ship of 13 750 tonnes displacement, GM 0.75 m, is listed degrees to starboard and has yet to load 250 tonnes of cargo. There is space available in each side of No. 3 between deck (centre of gravity, 6.1 m out from the centreline). Find how much cargo to load on each side if the ship is to be upright on completion of loading.

Example 10 A ship of 9900 tonnes displacement has KM 7.3 m and KG 6.4 m. She has yet to load two 50 tonne lifts with her own gear and the first lift is to be placed on deck on the inshore side (KG 9 m and centre of gravity 6 m out from the centreline). When the derrick plumbs the quay its head is 15 m above the keel and 12 m out from the centreline. Calculate the maximum list during the operation