2-66 BOAT HULL DESIGN 



Shear Stress: 



Shear load, V = EJLk (2.24) 



2 



0.89 x Ii8 = 21.1; lbs. per in. 



2 



Assuming the core material carries all the shear load, the 



maximum shear stress for a rectangular block is for e 1-l/u in. core: 



f s = | J (2.27) 



f s ■ I = rrr^ = 25 - 7 psi 



Allowable shear stress, fsa = Ultimate Shear Stress (Table 5 _ 17)(2 . 9a) 



' Factor of Safety 



f sa = { °' = )|6.3 psi Satisfactory 



See Design Example 2-4 for notes regarding this shear calculation. 



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

 these calculations are given below in tabular form, Table 2-11. 



Deflection: 



Allowable deflection, d = = ^- = 0.2h in. 



200 200 



Assume a cellular cellulose acetate core weighing 7.0 lbs. per cubic ft. 



G c = 2.0 x 103 psi (Table 5-17) 



Ultimate shear strength = 185 psi 

 Try a 1-l/h in. core 



Maximum deflection, d = -& + E£ (2. 28) 



381j E f I f 8 G C A C 







.89 x hSh 0.89 x h8 2 



" 381i x 2.06 x 10° x .0h6 8 x 2000 x 1 x 1.25 (Fig. 6-53b)> 



= 0.130 in. + 0.103 



= 0.233 in. Satisfactory 



* By extrapolation. 



