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will be reduced, and the vertical line through G will begin to move 
out faster than C ; the righting arm will then be diminished by any 
further heeling. The angle at which this takes place depends on 
: the form of the boat, and the position of her centre of gravity, 
| and varies in common types of boats as much as from 10° to 50°. 
Such a section as that represented in our figure, gives a boat 
___ ofgreat stability. At a moderate heel, C will move rapidly out, and 
. the stability will, if G be kept low, continue to increase till the gun- 
wale touches thewater. The excellence of the design depends on two 
, things, a broad flat floor, and a moderately high side, nearly vertical 
from the water upwards. The advantage of a high side is obvious, 
since it allows the boat to heel over without swamping. The 
flat floor gives the best results as to stability. Compare Figs. 4 
and 5. They represent sections, the one of a boat with a perfectly 
flat floor, the other of a deeper boat with a nearly triangular section. 
The displacement, and therefore the weight, is the same for both. 
The centres of gravity are put about where they would be if each 
boat had its usual complement of people on board, all sitting 
‘down. The centres of buoyancy have been ascertained with 
sufficient accuracy, each boat being heeled over to an angle of ten 
degrees. The figures therefore afford data for a comparison of the 
stability of the boats under ordinary circumstances, and the com- 
parison will be complete if we simply measure the arms of the 
righting couples. Now it will be found that the arm of the couple 
tending to right the flat floored boat is rather more than three 
times as long as the arm of the righting couple for the sharp 
_ floored boat. Hence the flat floored model is more than three 
times as stable as the other, the centre of gravity having such a 
position as it would commonly occupy. But this is not all its 
_ advantage. If a mast were set up in the boat, or if any of the 
_crew were to stand up, the centre of gravity would be raised. 
If it were raised as far as the point M, so as to be vertically 
above the centre of buoyancy, the stability of the boat would 
vanish; and if it were raised any further, the boat would 
F capsize of her own accord. Now, referring to Figs. 4 and 5, it 
will be seen that M is very high for the flat floored boat, and 
‘ 14 
