BOAT HULL DESIGN 2-43 



Side Longitudinals: The side longitudinals are designed to support a pressure equivalent 

 to a head of water to 6 in. above the deck. The longitudinals are designed as uniformly loaded, 

 fixed ended beams. 



Consider Longitudinal No. 6 between the transverse and the bottom of the motor well. 



Stiffener Spacing = 10.5 in. 



Load = head of water to 6 in. above the deck at side 



Factor of Safety = k 5 F C u = 15,800 psi (Table 5-11) 



Pressure = Head x Density of Sea Water 



= 1.56 x oU = #?03 osi 

 Ikh 

 Load per inch = .703 x 10.5 = 7.38 opi 



Bending Moment, H = |j- (2.21) 



= 7.38 x (8l) 2 = mk in ._ lbs . 

 12 



Required Section Modulus, Z = F<S> x M (2.22) 



F cu 



7 _ h x U03U = i 02 in 3 



z " 15^,800 i-J ^ ln " 



From Fig. 6-37, use 1-1/2 in. wide x2 -1 /2 in. deep stiff eners with 5 plies of woven roving. 



Decks: Fore Deck - Laminate: Similar to shell laminate; Framing: 3 equally spaced 

 deck longitudinals, Loading: Head equivalent to 2 ft. of water = 0. 89 psi, Factor of 

 Safety = 4. 0. 



Laminate Design: The panel is considered fixed ended due to the continuous load and 

 continuity of the laminate. 



Stiffener spacing = 19 in. 



Stiffener width = 1| in. 



Unsupported span of laminate = 15 in. 



Bending moment, fi = °' 89 (1 ^ = 16. 7 in. -lbs. (2.21) 



Required Section Modulus, Z = — '— '- (2. 22) 



F bu 



Ultimate Flexural Stress, F bu from Table <-9 



1 = k'° x 16.7 = 0.0033 in. 3 Mat 

 20,500 



z = h.O x Is. 7 = 0.0028 in. 3 Woven Roving 

 23,700 



Z = lj.0 x 16.7 = 0.0021 in. 3 Cloth 

 31,100 



