lemniscate hull

The Lemniscate Hull

A Chineless Gull Wing

By Bill Beran

I built this 16′ runabout in my garage over the course of a few years. It was the culmination of an idea I long had for a design that would provide a soft ride with its deep-vee hull, but at the same time exhibit excellent fuel economy. It’s best described as a chineless gull wing. The hull shape captures and efficiently redirects otherwise wasted bow wave energy downward to create lift. It also safely captures ram air under the “wings” (noticeable starting about 40 mph) and attains a comfortable top speed close to 50 mph with the 115hp outboard motor.

The boat is essentially plywood construction glued together with WEST SYSTEM 105 Resin and 206 Slow Hardener, thickened with 404 High-Density Filler. It is also fastened with stainless steel screws. The internal structure in the higher stressed transom area has its thick plywood intersections reinforced with epoxy-glued 1 ½” wood gussets. For thinner parts, I reinforced the epoxy glued joints with epoxy thickened with 405 Filleting Blend. I used a still thinner version of epoxy and 405 to fair the hull surfaces.

It’s configured as a hull within a hull, with all enclosed spaces between the hulls filled with pour-in-place 2 lb./cu.ft. urethane foam to make the boat virtually unsinkable.

bow cavity

Bow cavity filled with foam and rough cut in preparation for sanding it fair. The total amount of foam in the boat gives it a buoyancy of 3,600 lbs.

Having designed and constructed seven other types of boats over the years, I paid a lot of attention to durability by encapsulating all exposed wood with 6 oz. fiberglass and five layers of 105 Epoxy using either 206 Slow Hardener or 207 Special Clear Hardener. On the hull bottom, I impregnated the last two coats of epoxy with 423 Graphite Powder. This gave me the black color I wanted and also provided long-term UV protection for the epoxy without the need for paint. The rest of the boat is painted with two coats of “Mist Gray,” a one-part polyurethane to protect the epoxy and reduce the surface temperature when in the sun. The transom, dash, and a few other areas are finished bright (not painted); these have a 0000 steel wool surface finish with UV-inhibiting wax coating protecting the epoxy.

windshield and bracing

The windshield and its bracing in the final stages of laminating

Normally kept trailered in my garage, the boat looks, sounds, and feels as good as it did when launched in the fall of 2012. I expect to see these qualities extended for many years to come, derived in no small part to the commendable caliber of WEST SYSTEM products.