52 



APPLICATION OF BUOYANCY BOXES TO THE STEAMSHIP 



It is a very simple matter to prove that both methods are identical. 

 Trim. — Professor Hovgaard's formula in figuring the trim is: — 



Trim = 



.Length of ship x weight of water up to original 

 W. L. X permeability % x lever around^ axis 

 Gi Mi. X displacement in tons 



or 



Displacements in tons x Gi Mi x trim ^ -y^gigjit moment. 

 Length of ship 



Gi Ml = Bx Ml when considering longitudinal stability. 

 D M - ^^ - '^i X -^ 



BlMi-y J^ 



For denotations see following figure: — 



JL_ 



/PX/J Ot=- ^£0UC£O Pl-fi^^ 



S/tGefi> M/L. 



Hence : 



i^xH^xTrim 

 35 ^ 



= §1^ = Weight moment, 

 35 



which is the section modulus formulae. 



In order to illustrate how the two methods compare we will finally consider 

 that the water plane of the ship is rectangular and has been reduced to half the orig- 

 inal length. 





