The Constant Camber (CC) construction method of creating curved plywood sheets on a single mold is efficient for multihulls as all of the hulls can be built on just one mold. The layered veneers are infused with epoxy creating strong, monocoque, virtually weather-tight hulls. We offer plans for Constant Camber dinghies, trimarans, and catamarans.
An Introduction to CONSTANT CAMBER
A Unique Construction Method
Constant Camber is an outside-in building method that results in a “molded plywood” boat. Unlike conventional molds, an individual CC mold can produce many different hulls within a limited length range. In fact, the ‘mold’ is actually a laminating form.
Full or partial length panels are laminated from veneer or plywood strips and glued with epoxy to produce frameless, two-piece hulls from a single unilateral mold. Series production of panels is made possible by the geometric elimination of “spiling” the individual laminating components. Patented by Jim Brown, this constant spile of each plank eliminates the labor-intensive hand fitting of pieces as they are applied to the mold. Panels can be assembled with various adhesives using either staples or vacuum bag for pressure while the adhesive cures. Vacuum bagging is the preferred method since it is faster and achieves a higher quality laminate with less adhesive and no staples in the middle of the panel. Unlike the complex vacuum pressure methods used in the aerospace industry, our vacuum bagging method is a fairly simple process requiring only common materials, most of which can be purchased at the local hardware store.
Dimensional stability is achieved without an internal skeleton by slightly torturing the compound panels during hull assembly which imparts “pre-stressed eggshell rigidity” to the panels. The resulting structure has extremely high strength for low weight and no flat areas. Most material is relegated to the skin, thus gaining adequate skin thickness that achieves good insulation and high impact/puncture resistance. Building a dimensionally perfect hull is accomplished without “framing up”; the mold and panels are self-fairing. Hull shape is established by the mold geometry plus the mating perimeters of the panels. Panels are also used for decks, wing fairings and cabins where appropriate on some designs.
Vessels that have been designed for this method range from extremely elemental Third-World sailing workboats to sophisticated high-performance yachts. Rigs, sails and outfitting are designed to appropriate standards. Furthermore, this design approach is seen as a means by which the larger multihull builder, and the small custom boat shop, can both be made viable in the marketplace. Panels may be laminated by individuals wishing to build only their own boats (at a mold investment of less than the cost of framing up the hulls) but with the important option of being able to produce more panels for other builders. Alternately, the mold and vacuum system can be sold to the next builder to return the investment.
Each CC plans package includes a complete set of working drawings, a list of veneer suppliers, our descriptive Panelmaking how-to booklet, our Liquid Joinery epoxy how-to booklet, and our Standard Details outfitting booklet. I’ll also include some other helpful articles on stainless steel rigging, making metal parts, anchoring. Consultation, to a reasonable extent, is included in the design fee to assure the successful completion of each vessel. Preparation and submission of all documents for U.S. Coast Guard certification for carrying passengers for hire is also included with plans for commercial vessels.