Free-form surfacing optimizes free-style kayak

The 6-ft/1.8m-long Project 54cx kayak, made using aramid and carbon fabric-reinforced composites, weighs only 19 lb/8.6 kg.

Confluence Watersports (Easley, S.C.) builds a unique blend of canoe and kayak brands, including Mad River Canoe, Wilderness Systems, Perception, Dagger and Wave Sport kayaks. Although most models are used for recreation and touring, the company also produces high-performance kayaks for whitewater competition, such as the Project 54cx from Wave Sport, which was paddled by Bryan Kirk to win the U.S. National Championship earlier this year. “We call it Project because it is always in beta testing,” says Confluence’s VP of design Bob McDonough. “We’re always trying to take performance one step further.”

A key tool in that ongoing process, says McDonough, is 3-D modeling software supplied by Rhino3D (Seattle, Wash.), which gives designers the ability to design boats purely for performance. “I can create a model and view the 3-D cross-section at any point to better evaluate the shape. I can also rotate it in 3-D and perform volume analyses,” he says. Confluence has used Rhino3D for nearly eight years. According to McDonough, it “offers unique free-form surfacing capabilities, which helps us iterate through various hull and deck shapes in the creation of our kayaks and canoes.”

When a design is completed, he explains, a model is then processed through a computer-aided manufacturing (CAM) software package to create a solid pattern for the vessel, using an in-house five-axis CNC machining system. “From the solid pattern, we either make a tool for our composite boats,” says McDonough, “or we have a metal tool produced for manufacturing our rotomolded thermoplastic boats.”

The 6-ft/1.8m-long Project 54cx kayak is made using aramid and carbon fabrics: 4.3-oz/yd² Kevlar plain weave (Kevlar fiber provided by DuPont Protection Technologies (Richmond, Va.), 6.3-oz/yd² carbon 2x2 twill and a 9-oz/yd² carbon unidirectional supplied by weaver JB Martin Ltd. (St. Jean Sur Richelieu, Quebec, Canada). The kayak is infused in two parts, using Derakane vinyl ester, supplied by Ashland Inc. (Dublin, Ohio), and then joined along the seams, using vinyl ester-impregnated fiberglass tapes. The Project 54cx weighs only 19 lb/8.6 kg, half that of a rotomolded boat.

“The Project 54cx really exemplifies how and why we use a modeling program,” says McDonough. “The hull’s combination of speed, pop to catch air, and smooth volume distribution — vital for handling and flotation — are all performance factors we achieve conceptually through 3-D modeling, first.”

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