The patented LapStitch™ building system makes it easy to build lapstrake, or clinker, boat hulls. The patent (US Patent No. 6,142,093) was filed in 1999 by Chris Kulczycki (founder of Chesapeake Light Craft, world leading manufacturer of boat kits, whom Arwen Marine represents in Europe).

LapStitch™ is a big step forward compared to both conventional "glued lapstrake" and "stitch and glue". On edge of each plank is rabetted to a depth of half the plywood thickness and a width that can be varied along the length of the plank but should remain at a maximum of about 10 mm, which gives plenty of gluing surface at the joint and is sufficient to obtain the graceful look of a classical lapstrake.

The planks "lock" into each other when stitched and the hull takes its shape by the combination of the plank shapes, with a little help from a couple of frames of bulkheads. No building jib is required, and muck less epoxy is consumed in the joints than with traditional methods, making for a lighter hull.

Drilling and inserting the stitches. The hull takes its own shape without help or constraint from any additional structure.

Gluing and filling the joints after stitching.

The hull above is a Sassafras 16, featuring 5 strakes per side, built in Lapstitch™. The darker rabett is visible on the edge of plank 5, bottommost on the left.

Over the last 30 years, the advent of modern adhesives and high quality marine plywoods brought about the first major innovation in lapstrake building methods: glued plywood lapstrake hulls. This method of planking produces very strong, stiff, and beautiful hulls that never leak. This is progress, to be sure, but glued lapstrake boats still require molds and arcane joinery skills. It isn't a process suited to amateurs.

In 1997, Chesapeake Light Craft developed a way to build lapstrake boats without molds or complex "rolling bevels" on the lapstrake planking. Using sophisticated computer design software, we are now able to devise hull shapes that will assume a round-bottomed shape without a jig or "torturing" of the wood. A special "rabbet", or groove, is machined into each strake so that they are self-aligning. They are wired together just like a stitch-and-glue kayak. When these joints are filled with epoxy, the result is a remarkably stiff and strong hull that has the appearance of traditional lapstrake planking. The patent was subsequently filed in 1999 (US Patent No. 6,142,093) by Chris Kulczycki.

The strength of the LapStitch™ joint is such that the designs require comparatively little fiberglass or fillet work, making them especially easy to build.