Page 143 - statbility for masters and mates

At 25 heel
Moments of statical stability 131
GZ GM 12 BMtan2y siny
1 12 3 tan2 25 sin 25 1 0:3262 sin 25
1:3262 sin 25
GZ 0:56 metres Moment of statical stability W GZ
3198 0:56
1790:9 tonnes m
Ans. (a) 278.9 tonnes m and (b) 1790.9 tonnes m.
The moment of statical stability at a large angle of heel may also be
calculated using a formula known as Attwood's formula: i.e.
Moment of statical stability W The derivation of this formula is as follows:
v hh
V
1 BG sin y
Fig. 14.6
Moment of statical stability W GZ
W BR BT
Let v the volume of the immersed or emerged wedge,
hh1 the horizontal component of the shift of the centre of gravity of the
wedge,
V the underwater volume of the ship, and