2-32 BOAT HULL DESIGN 



available. For illustrative purposes, it is assumed that this calculation has been made and 

 the stays chosen are 3/32 in. diameter, 1 x 19 stainless steel wire rope with a breaking 

 strength of 1200 pounds (17). The chain plates are designed to the yield stress of the ma- 

 terial and the supporting fiberglass laminate to a factor of safety of 2. 



Stay Connection: 



Stainless steel chain plate and pin; 



Tensile Yield Stress, F ty = li0,000 psi (Reference 18) 



Shear Yield Stress, F S y = 0.6 x F-j-y = 21^,000 psi 



Consider pin in double shear and load P = 1200 lbs.: 



Required ran area, A D = (2. 11) 



1 2 X F S y 



A,, = 1? . ° . ° . = 0.02^ sq. in. 



1 2 x 2h,000 



Chain Plate: 



Use 3/lo in. Din diameter; Area = 0.035 sq. in. 



Thickness required for bearing of pin; 



fearing Yield Stress, F By = 1.5 x 2ij,000 = 38,liOO psi 



Rearing load, P = 1200 lbs. 



t = 1 (2.12) 



Fpy X D 



1200 „ 1(rc . 



t = = 0.1o'o5 in. 



38,liOO x 0.1875 



Use 0.18?^ or 3/l6 in. thick plate 



Chain Plate Fastening to Hull: The chain is passed through the gunwale and fastened 

 to a transverse bracket, which is connected with bonding angles to the shell. The bracket 

 is used in lieu of bolting directly through the shell for appearance. 



Assume the bracket is made of 5 plies of woven roving, and the bolts are 1/8 in. 

 diameter stainless steel. Design for the wire to fail without permanent deformation of 

 the laminate: 



Total load, P = 1200 lbs. 



Laminate thickness, t = .185 in. (Table 5-2) 



Bearing area per bolt = Bolt diameter x Laminate thickness 



A B = D x t (2.13) 



A B = 0.125 x 0.185 = 0.023 sq. in. 



