BOAT HULL DESIGN 



2-55 



Try a 3A in « thick core of cellular cellulose acetate; 7 lbs. per cu.ft. density. 



E f I f = 2.06 x 10 6 x 0.0172 = 0.036 x 10^ 



G c A c 



2.0 x 103 x 1 x 0.75 = 1500 



(I from Fig. 6-53b) 

 (G from Table 5-17) 



M • n *n 4.- j O.89 x 33^ 0.89 x 33 2 

 Maximum Deflection, d = — r + £z— 



38U x 0.036 x 10° 8 x 1500 



= 0.076 in. + 0.081 = 0.157 in. 



Therefore deflection is the controlling criterion and a 3/h In. deep 

 core is required. 



By similar calculations the remainder of the decks may be checked. The results of 

 these calculations are given below in tabular form, Table 2-8. 



TABLE 2-8. DECKS 



The deflection of this deck is slightly in excess of the allowable, 



but is considered acceptable since this is not a normal walking space. 



Ultimate Shear Stress of 7 lb. per ft 3 density CCA = 185 psi (Table 5-17). 



Built-in Bunks: Design Loading - 40 lb. per ft 2 (0. 28 psi) on horizontal surface. 



Design Criteria: Horizontal surface to be checked as a plate in bending. Vertical 

 surface to be checked for column loading. 



Factor of Safety = 4. in bending; 2. on buckling stress in compression. 



