The ins and outs of stitch-and-glue
Posted on 29 March 2010
Written by Dieter Loibner
"When I started out, wood-epoxy boat construction had the worst possible reputation," Sam Devlin explains.
"But it's improved." More than that, stitch-and-glue is "pure sanity" to Devlin.
Yes, it's labor-intensive, he admits, but it results in a wooden boat that an average owner can maintain with few hassles. And the building method is simpler, because there are fewer parts to assemble than in traditional plank-on-frame construction.
The drawback is that simple stitch-and-glue designs characteristically are hard-chined, which might seem limiting to some. Devlin, however, counters. Plywood, he says, mostly results in hulls with chines, but that does not diminish performance. To the contrary, the current trend in sailboat design seems to rediscover the virtues of the chine and proven boats like the Optimist, Snipe, Lightning and Star, which thrive on hard edges.
Stitch-and-glue uses high-grade marine plywood, wire sutures, fiberglass tape, fiberglass or Dynel cloth for sheathing, and epoxy fillers and resin. The plywood panels are held together with the wire sutures or staples until the interior seams are fused with a thickened epoxy filler and resin-saturated fiberglass tape. Once the filler and tape on the inside of the hull are completely cured, the wires are removed. Depending on the size of the boat, the exterior either receives the same treatment or the plywood skin has additional layers of marine plywood laminated onto it to increase the thickness and strength.
In the next step, seams and edges are faired before the hull is sheathed in fiberglass or Dynel set in epoxy resin. The result, according to Devlin, is a hull that's watertight and strong. In the long term, he says, the boat is easier to maintain because the wood is completely sealed, inside and out, which keeps out moisture so paints and finishes are less prone to cracking and peeling, and the wood is protected from rot. With no molds or tooling,
Devlin says, stitch-and-glue hull designs are free to evolve.
With so many advantages, why has stitch-and-glue remained a sideshow in modern boatbuilding? "It hasn't been publicized very well, and we have nobody else to blame but ourselves," Devlin says. "Production builders who are squeezed by the recession don't realize how approachable plywood construction is. If they did, they might look at it as an option to improve their bottom line, because any savings are beneficial to staying in business."
See realted articles:
- Sam Devlin - designer, builder, tinkerer
- A first-time boatbuilder dives right in
This article originally appeared in the May 2010 issue.