When a ship of 10000 tonnes displacement is heeled 15 degrees, the righting lever is 0.2m, KM 6.8m. Find the KG and the moment of statical stability.

When a ship of 10000 tonnes displacement is heeled 15 degrees, the righting lever is 0.2m, KM 6.8m. Find the KG and the moment of statical stability.

Reference: Ship Stability for Masters & Mates (6^th edition), Exercise – 15.4

 

Solution:

Righting Lever (GZ) = 0.2 m

Moment of Statical Stability = w*GZ

                                              = 10⁴ * 0.2

                                              = 2000 tons-m

Again,

Moment of statical stability = w * GMSin θ

=> GM = moment of SS/ w*Sin θ

=> GM = 2000/ 10⁴ * Sin15⁰

=> GM = 0.77 m

 

KG = KM – GM = 6.8 – 0.77 = 6.027 m