Page 51 - statbility for masters and mates

Effect of density on draft and displacement 39
changed. The change in the mass of water displaced may have been brought about by bunkers and stores being loaded or consumed during a sea passage, or by cargo being loaded or discharged.
In all cases:
New volume of water displaced Old volume of water displaced
or
or
Example 1
New displacement Old displacement New density Old density
New displacement New density Old displacement Old density
A ship displaces 7000 tonnes whilst ¯oating in fresh water. Find the displace- ment of the ship when ¯oating at the same draft in water of density 1015 kg per cubic metre, i.e. 1.015 t/m3.
New displacement New density Old displacement Old density
New displacement Old displacement New density
7000 1015 1000
Ans. New displacement 7105 tonnes
Example 2
A ship of 6400 tonnes displacement is ¯oating in salt water. The ship has to proceed to a berth where the density of the water is 1008 kg per cu. m. Find how much cargo must be discharged if she is to remain at the salt water draft.
Old density
or
New displacement New density Old displacement Old density
New displacement Old displacement New density Old density
6400 1008 1025
New displacement 6293:9 tonnes Old displacement 6400:0 tonnes
Ans. Cargo to discharge 106:1 tonnes
Example 3
A ship 120 m 17 m 10 m has a block coef®cient 0.800 and is ¯oating at the load Summer draft of 7.2 metres in fresh water. Find how much more cargo can