BOAT HULL DESIGN 2-33 



Allowable Bolt Fearing Stress - from Table 3-2 and for no permanent deformation: 



^Ba = •6Hl x Laminate ultimate tensile strength 



F Ba = ,6iil x 32,900 = 21,070 psi - Table 5-6 for Ultimate Tensile Stress 

 Allowable bearing load per bolt = Bearing area x Allo;vable bearing stress 



P Ba = A B x F Ea ( 2 . 14) 



P r;a = 0.023 x 21,070 = h88 lbs. 



Required number of bolts ; N = _i — (2. 15) 



PBa 



N = i££0 = 2J[6 hQlts 

 I400 



Use three bolts . 



Chain Plate Width: 



Total Width = Diameter of pin + 



b = D + 



thickness of plate x tensile yield stress 



P 



t x F ty (2. 16) 



t = i in. = 0.187? in. 

 16 



b = 0.1875 + i£22 = 0.3h75 in. 



0.1375 x lj0,000 



Use a 1-1/8 in. wide x 3/16 in. thick plate minimum. 



Required Vertical Length of Bracket: Assume load carried in shear by shell to bracket 

 connection, which is made of two 2 in. x 2 in. fiberglass polyester resin angles. The angles 

 are made of one ply of 1-1/2 ounce mat against the bracket and shell and two plies of woven 

 roving. The connection between the angles and the shell and bracket is in secondary bond 

 with polyester resin. 



Ultimate Bond Shear Stress, F_ = 1000 psi 



dSU 



Factor of safety, F.S. = 2.0 



Vertical length of bracket, L = '— (2. 17) 



Bond Width x Fg su 



1200 x 2 n <n • 

 L = = 0.60 in. 



2 x 2 x 1000 



The shear connection is obviously not critical so the bracket is made 8 inches long to 

 accommodate the length of the chain plate and provide a reasonable taper at the bottom as 

 described in Chapter 3. 



Hull Support for Chain Plate: The slope of the side stay places a horizontal load on 

 the gunwale causing bending and local compression. 



