Page 180 - statbility for masters and mates

168 Ship Stability for Masters and Mates
Example 3
Find the righting levers for M.V. `Cargo-Carrier' when the displacement is 40 000 tonnes and the KG is 10 metres.
Heel y KN siny
KG siny 0.87
1.74 2.59 3.42 5.00 7.07 8.66 9.66
10.00
GZ KN KG siny 0.03
0.18 0.52 0.83 1.30 1.37 0.73
0.37 1.50
5 0.90 10 1.92 15 3.11 20 4.25 30 6.30 45 8.44 60 9.39 75 9.29 90 8.50
0.087 0.174 0.259 0.342 0.500 0.707 0.866 0.966 1.000
2. Statical Stability curves
The curve of statical stability for a ship in any particular condition of loading is obtained by plotting the righting levers against angle of heel as shown in Figures 16.4 and 16.5.
Fig. 16.4. Curve for a ship with positive initial metacentric height.
From this type of graph a considerable amount of stability information may be found by inspection:
The range of stability. This is the range over which the ship has positive righting levers. In Figure 16.4 the range is from 0 degrees to 86 degrees. The angle of vanishing stability. This is the angle of heel at which the
righting lever returns to zero, or is the angle of heel at which the sign of the