2-54 BOAT HULL DESIGN 



Design Load: p = 2 ft. of water = 0. 89 psi 



Flexure: 



Considering a 1 in. strip as a fixed ended bean. 



Bending Moment, M * EJL - °' 9 x 33 = 80.7 in.-lbs. (2.21) 



'12 12 



Ultimate Stresses, F from Tables 5-6 and 5-11 



Cloth: top face in tension Z = a x 80,7 = 0.0131+ in. (2.22) 



2U,100 



l/l; in. deep core required. (Fig. 6- 53b) 



Woven Roving; bottom face in compression Z = -i— — = 0.0232 in. 3 (2. 22) 



3/8 in. deep core required. (Fig. 6- 53b) 



Mat: top face in tension Z = 3 x 80,7 . = 0.029U in. 3 (2.22) 



11,000 



l/lt in. deep core required. (Fig. 6 -53b) 



Shear Stress: 



Maximum Shear Load, 7 - £& (2.24) 



' 2 



„ 0.89 x 33 



v p 14.7 lbs. per in. 



Assuming the core carries all the shear load. 



Shear stress, f s . | { (2.27) 



f s = - x r-7-g = 29.1; psi 



Allowable Shear Stress, f = Ultimate Shear Stress (2.9a) 



sa Factor of Safety 



f sa = 1 = ^ 6 «3 Psi Satisfactory (Table 5-17) 



This shear stress calculation is approximate and over estimates the shear stress in 

 the core. A more accurate stress value may be obtained by the methods explained in 

 Chapter 6. 



Deflection: 



1 33 



Allowable Deflection, d = — — = — — = 0.165 in. 



Maximum Deflection, d = V + | Q (2.28) 



