Stability – I : Chapter 8

1. A box shaped vessel of displacement 1640t is 50m long 10m wide and 8m high . Find her KB in SW , if she is one an even keel and upright.

Solution:

Displacement = 1640

Volume of box shape vessel = (L x B x H)
= (50m x10m x 8m)

RD = 1.025

Displacement = (u/w volume) x(density of water displaced)
1640         = ( L x B x d )  x (1.025)
1640              =(50 x 10 x d) x (1.025 )

Hence, d =   1640/ (50 x 10x 1.025)
= 3.2m

As we know that  KB can be calculated as
= (d/2)
= (3.2/2)
= 1.6m

2. A box shaped vessel 60m x 10m x10m floats in DW of RD 1.020 at an even keel draft of 6m . Find her KB in DW of RD 1.004.

Solution :

Volume of box shape vessel = ( L X B XH)
=(60m x 10m x 10m)

RD = 1.020,
Draft = 6m

Displacement at RD of 1.020 = (u/w volume)x(density)
=    ( L x B x d ) x 1.020
= (60 x 10 x 6) x 1.020
= 3672t

Now we have to calculate draft of vessel at RD of 1.004,
keeping the displacement same    = (L x B x d ) x (1.004)
3672 = (60 x 10 x d )x (1.004)
d = 3672 /(60 x 10 x 1.004)
= 6.095m

Hence,     KB = (d/2
= (6.095 /2)
= 3.047m.