Page 168 - statbility for masters and mates

156 Ship Stability for Masters and Mates
; GML Lt GG1 120 0:2
0:15
Ans. GML 160 metres
Example 2
A ship 150 metres long has a displacement of 7200 tonnes, and is ¯oating upright on an even keel. When a weight of 60 tonnes, already on board, is shifted 24 metres forward, the trim is changed by 0.15 metres. Find the longitudinal metacentric height.
GML L GG1 t
GML GG1 Lt
w d L Wt
60 24 150 7200 0:15
Ans. GML 200 metres
Summary
1 Make a sketch from the given information.
2 Estimate the mean bodily sinkage.
3 Calculate the change of trim using levers measured from LCF.
4 Evaluate the trim ratio forward and aft at FP and AP, from the LCF
position.
5 Collect the above calculated values to estimate the ®nal end drafts.
6 In the solutions shown in the text, these ®nal end drafts have been
calculated to three decimal ®gures. In practice, naval architects and ship- of®cers round off the drafts to two decimal places only. This gives acceptable accuracy.
7 Note how the formulae were written in letters ®rst and then put the ®gures in. In the event of a mathematical error, marks will be given for a correct formula and for a correct sketch.