A box-shaped vessel 18 x5 x2 m floats in DW of RD1.000 at a draft 1.4m. Calculate her percentage reserve buoyancy when she enters the SW .

Solution:

Volume of box shape vessel = (L x B x H )
= (18m x 5m x 2m)

RD of DW = 1.000 & Depth = 1.4m

Displacement at DW of RD 1.000 (W)
= (u/w volume)x (density)
=( Lx B x 1.4) x(1)

Displacement at SW (W1) = (u/w volume) x (density)
=(L x B x Draft) x (1.025)

Since, Displacement of ship will remain constant with change of density as displacement of vessel is refer as MASS.

W = W1
(L x B x 1.4) x (1) = (L x B x Draft) x (1.025)

Hence, Draft = (1.4/1.025)
= 1.365m

Total volume of the ship = (L x B x H)
= (18 x 5 x 2)
= 180m3

Again, U/w volume of SW = (L x B x draft)
=(18 x 5 x 1.365)
= 122.85m3

Above water volume = (180 -122.85)
= 57.15m3

Hence, RB % = (Above water volume/ Total volume) x 100
= (57.15/ 180) x 100
= 31.75%.