DESIGN DETAILS 



3-3 



A joint should be compatible with the molding method used, the speed of con- 

 struction desired, and the size and type of boat being built. A joint which has 

 adequate strength and can easily be made with minimum mold accuracy for 

 small boats, may not be suitable for use with larger boats with higher strength 

 requirements. These larger boats are not rapidly produced, and therefore 

 justify the extra cost of using one of the more complex joints requiring more 

 accurate molds. The parts to be joined should never be forced into place, 

 since this introduces stresses not contemplated in the design and may drasti- 

 cally reduce the strength of the structure. 



Normal loads on the deck and shell produce either shear loading, or tension 

 loading on the outside of the hull at the joint. It is the tension on the outside 

 of the hull which makes exterior reinforcement so effective when compared 

 to interior reinforcement. With interior reinforcement only, this type of 

 loading tends to peel the pre-molded laminate away from the bonding rein- 

 forcement as shown in Fig. 3-2. For this reason, this connection must be 

 very carefully made. It is recommended that the bond lap be at least 2 inches 

 in small boats, and be adequately increased for larger hulls with thicker 

 laminates. 



When joints are used which leave an edge of a laminate that is not tapered 



or butted to an adjacent piece, this edge should be sealed with resin to prevent 



water absorption and delamination. 



v — DECK LOADING 



BONDED LAMINATES 

 TEND T O PEEL APART 



SI DE SHELL 

 LOAOI NG 



PRE-MOLDED 



FIBERGLASS JOINT REIN-' 

 FORCEMENT COVERING HEADS 

 OF BOLTS 



WOOD COAMING 



PRE-MOLDEO 

 SHELL LAMI NATE 



Fig. 3-2. Deck Edge 

 Connection - Normal Deck 

 and Shell Loading Produces 

 Tension at the Joint 



Fig. 3-3. Deck Edge Connection 

 Shaped Wood Gunwale Clamp 



Figs. 3-3 through 3-12 indicate several deck to shell connections. 



Fig. 3-3 indicates the use of a shaped wood gunwale clamp. This was common practice 

 in past years, and was adapted from wood boat construction, but the current trend is to 

 the all fiberglass boat. Several reasons for this have been given in the discussion of com- 

 posite construction, Chapter 2. 



