Page 199 - statbility for masters and mates

Water pressure 187
Exercise 18
1 A sealed box is made of metal and is capable of withstanding a pressure of 15.54 kN per sq m. Find to what depth the box may be submerged in salt water before it collapses.
2 Find the water pressure, in kilo-newtons per sq m, on the keel of a ship which is ¯oating upright on an even keel in salt water at a draft of 6 metres.
3 A ship is ¯oating on an even keel in salt water at a draft of 7 metres. She has a ¯at plate keel which is 100 m long and 2 m wide. Find the water pressure and the total thrust on the keel due to the water.
4 Find the water pressure and thrust on a ¯at plate keel 6 m long and 1.5 m wide when the ship is ¯oating on an even keel at 6 m draft in salt water.
5 Find the water pressure and thrust on the inner bottom plating of a double bottom tank (10 m 10 m) when the tank is ®lled with fresh water to a
head of 9 m above the crown of the tank.
6 A deep tank has two lids, each 4 m 3 m, resting on coamings which are
30 cm high. Find the water pressure on each of the two lids and the total thrust on both lids when the tank is ®lled with salt water to a head of 6.3 m above the crown of the tank.
7 A rectangular plate 2 m 1 m is held vertically in fresh water with the 2 m edge on the waterline. Find the thrust on one side of the plate.
8 A lock gate 12 m wide has water of density 1010 kg per cu. m to a depth of 10m on one side and water of density 1015kg per cu.m to a depth of 6 m on the other side. Find the resultant thrust on the lock gate and state on which side it acts.
9 A lock gate is 20 m wide and has water of density 1016 kg per cu. m on one side to a depth of 10 m and salt water on the other side to a depth of 7.5 m. Find the resultant thrust and state on which side of the gate it will act.
10 Find the total water pressure acting on a box-shaped barge keel plating which is 60 m long 10 m wide, and is ¯oating upright in salt water on an even keel at 5 m draft.
11 A box-shaped barge has a rectangular collision bulkhead 10 m wide and 6 m deep. Find the total water pressure on this bulkhead if the forepeak is ¯ooded to a depth of 5 m with salt water.