Clara, a modest and deceptively simple launch, is the latest powerboat project from U.K. yacht designer Nigel Irens, and a timely reminder that boating can be simple, efficient, affordable, and ultimately pleasurable. In a year defined by supply-chain disruptions, fuel scarcity, and broad economic uncertainly, the 26‘3“ (8m) open boat with a scant 6‘6“ (1.98m) beam and 1,825-lb (827.8-kg) displacement offers a uniquely refined model intended to be built of CNC-cut plywood and epoxy in a modest shop and powered by a 20-hp outboard or equivalent electric motor.
Regular readers of the magazine will recognize this as the latest iteration in Irens’s refinement of low-displacement/length (LDL) hullforms that defy the accepted wisdom that 1.34 times the square root of the waterline length in feet defines the hull speed of a displacement vessel. (For details on Irens’s earlier LDL designs, see “Slippery When Wet,” Professional BoatBuilder No. 187, page 68.) Indeed, Irens reported that the new boat reached 12 knots in sea trials, nearly twice her theoretical hull speed. No surprise, as Clara’s hullform pushes the LDL form to new extremes, with the forefoot a little deeper and the beam a little narrower than Irens’s previous models. The plumb bow and very fine entry yield a hull that resembles a wood-splitting maul. It’s an evolution of the early design process Irens described to me over the phone during COVID isolation two years ago: Take a cardboard toilet-paper tube and pinch the ends together perpendicular to one another. The result is his basic LDL hullform. He explained further that sharpness is essential to his design’s efficiency, from the wave-cleaving stem to the crisp transom trailing edge, which separates cleanly from the water that wants to cling to the hull’s running surface at speed.
There’s more to Clara than exceeding performance predictions. For years Irens has been thinking about efficient construction methods for his lightweight wood-epoxy powerboats that would ensure consistency of hull shape, structural integrity, and performance and be accessible to a global market. By optimizing CAD design files for computer-controlled cutting technology—waterjets and multiaxis routers—he says he’s confident that the shapes and quality of essential fit will be uniform and not depend entirely on the builder’s hand skills and experience. At a time when recruiting and retaining a skilled workforce have become major challenges for boatbuilders, the ability to cut accurate curves, bevels, lapped joints, and faying surfaces with a CNC router is a huge advantage.
The results should be fairly uniform wherever the boat is built. Ideally, the refined CAD files will make it possible to cut an identical kit of parts anywhere in the world from locally available marine plywood, and for a local builder with a modest shop to put it together with a minimum of fuss—just like she goes through the water.
Details of Irens’s design process and of the builds are documented at the Clara Boat website.
Clara Boat Co Ltd, 10 Market Close, Ashburton, Devon TQ13 7FN, U.K.