Lapstrake

From ClassicBoatWiki

Lapstrake boats are characterized by a "ridged" (not smooth) appearance to their hull sides . Like Plank on Frame constructed boats, lapstrake boats have an underlying framework. This framework gives the hull its shape.

Lapstrake boats are planked with overlapped boards, or "strakes." These strakes are laid from the keel up to the gunnel. The overlapped strakes give a lapstrake constructed boat its distinctive appearance, with the hull sides patterned like overlapping clapboard house siding. Unlike a carvel plank on frame boat, much of the strength in a lapstrake constructed boat comes from the laps, or overlapping strakes themselves. Each plank overlap, creates a double-thick, mechanically fastened, and often glued joint. These plank laps all contribute to the longitudinal strength of the hull.

Strakes are usually attached to steam bent frames with screws. Between frames, the plank laps were usually held tight with clinch nails—a nail that is driven through the planks and clenched or "bent over." Some manufacturers instead used a rivet and rove method. This method utilized copper nails, driven though both planks. Instead of being clinched, the nail received a washer (rove), and was then cut, and peened over, forming a head against the rove.

Lapstrake construction has been in use for hundreds of years, and creates a very strong durable boat hull. Lapstrake boats are also referred to as "clinker-built" boats. Lapstrake boats typically have a round bilge, with a soft rounded chine. This bottom design gives lapstrake boats their characteristic soft ride, and stability.

Lapstrake boats were popularized by such builders as Lyman, Thompson, Century, Grady-White and Chris-Craft, who built their first "Sea Skiff" in 1953 and launched their Sea Skiff Division in 1954.

Traditional lapstrake boats were made from full-thickness lumber. After WW-II many of the manufacturers utilized plywood in their designs. The use of plywood and space-age sealants was learned by many in fulfillment of their government contracts.

Chris-Craft, as an example, built traditional full thickness plank lapstrakes, and later moved to plywood with their Cavalier Sea Strake lineup. Chris-Craft also had some boats that were of hybrid construction utilizing sheet plywood bottoms, with straked sides and others with lapstrake bottoms and mahogany planked sides.