A box-shaped vessel of 3200 tonnes displacement has GM 0.5m and beam 15m, and is floating at 4m draft. Find the moments of statical stability at 5 degrees and 25 degrees heel.

A box-shaped vessel of 3200 tonnes displacement has GM 0.5m and beam 15m, and is floating at 4m draft. Find the moments of statical stability at 5 degrees and 25 degrees heel.

Reference: Ship Stability for Masters & Mates (6^th edition), Exercise – 15.7

 

Solution:

For 5⁰

Moment of statical stability = w*GMSinθ

                                              = 3200*0.5*Sin5⁰

                                              = 139.44 tons-m

For 25⁰

BM = B²/12d

       = 15²/12*4

       = 4.687 m

Moment of statical stability = w*(GM+0.5*BMTan²θ) * Sinθ

                                              = 3200* (0.5+0.5*4.687*tan25²) * Sin25⁰

                                              = 1365.4 tons-m