228 Variation of Stability with Draught of Water in Ships. 



modification in a direction which is disadvantageous to light draughts. 

 When there are equal volumes above and below water in this vessel, 

 the righting moments at the light draughts are generally much less 

 than at the deep draughts, except when the centre of gravity is raised 

 excessively, and, for this class of ship, unusually high. 



Fio. 15. Fig. 16. 



The analogy that exists between light draught and deep draught 

 stability in floating bodies of approximately symmetrical forms, and 

 particularly the point of resemblance afforded by the fact that what 

 is a wedge of immersion in one case is that of emersion in the other, 

 and vice versa, cannot fail to have struck some who have had to 

 calculate the stability of bodies floating at light draughts, but atten- 

 tion has never been prominently called to it. It is desirable, how- 

 ever, that the connexion between the two cases should be fully 

 realised, and the dangers peculiar to very light draught of water 

 appreciated as thoroughly as are those which attach to low freeboard. 

 Just as was said in 1871, in a passage already quoted, that meta- 

 centric height was formerly, by general consent, taken as a sufficiently 

 good standard of comparison in judging of the stability a ship would 

 have, on account of " the vague impression that the angle would be 

 very large at which the ship became unstable," so, since the intro- 

 duction of curves of stability, the dangers attaching to light draught 

 have been frequently lost sight of, because of the equally vague impres- 

 sion that, so long as a vessel has a high side out of water, and any 



