Stability with Draught of Water in Ships. 



225 



BR x V at angles of inclination of 30 and 60 respectively ; and ApjO, 

 Ap. 2 o are the corresponding curves of GZxV, or curves of righting 

 moments, when G is taken in the position it would occupy if the body 

 were homogeneous. The lines a ] x l and a^x^ indicate draughts at 



FIG. 12. 



which equal volumes are cut off above and below water, and mm' 

 shows the depth at which the immersed portion is one-half of the 

 total volume of the body. 



It will be seen that the righting moments are greater at 30 and 

 60 of inclination when the body is deeply immersed than when it is 

 floating at light draughts with equal volumes below water to those 

 which are above in the other case. The relation between the righting 

 moments at the two extremes of draught is, however, largely deter- 

 mined in a ship by the position of the centre of gravity, which in 

 this case has been taken as for a homogeneous body. This will be 

 seen by the next example. 



Fig. 13 gives curves of BR x V for an actual ship, at 30, 60, and 

 90 of inclination respectively. The vessel for which these have been 

 constructed is 400 feet in length, 44 feet in breadth, and 32 feet 

 inches in moulded depth. The extreme depth from the top of keel 

 the highest point of the sheer of the upper deck is 40 feet. The 

 sint O is the top of the keel, A is the highest point of the sheer of 

 deck, and AI the lowest point of the upper deck at side, from 



VOL. XXXVII. Q 



