The battle over plywood looks like a minor skirmish compared to the great glue debate. “Of all the materials that go into a plywood boat,” acknowledged boat builder and author Dynamite Payson, “the choice of glue causes the most controversy.” And for understandable reasons. The glue must hold the boat together, even under extreme stress, and even when the boat is soaked to the bone. Obviously, I need something more than Elmer’s Glue-All. I don’t want to be in the middle of the Chesapeake Bay when my hull decides to separate into its constituent parts.
So I go back to the various woodworking forums and, once again, I am thrust into a vigorous debate. Predictably, it comes down to two sides: Dominating the debate are those who believe that “only the best will do.” For them, the only category of adhesive a responsible and farsighted boat builder would consider is marine epoxy. There are several brands, but all are sold in two parts (which is why they are often called “two part epoxy”) that are mixed together just before applying. They are expensive and messy, but they produce a very strong and completely waterproof bond.
The Stevenson boat, however, calls for something called plastic resin glue. It is sold as a powder, mixed with water, and applied with a paintbrush. It’s an old standby and cheaper than epoxy.
Without any preconceived opinions, I’m ready to follow the recommendations of the boat’s designers, but comments made by the online boat building community give me pause. Because plastic resin glue doesn’t fill gaps in wood, as epoxies do, water can seep in and weaken the bond, they say. Others point out that it is less waterproof than epoxies and is, in fact, no longer officially listed as a “waterproof” glue. It doesn’t hold up in boiling water tests, which mean that, if placed for an extended period of time in boiling water, the bond can fail.
Suddenly, I find myself second-guessing the boat’s designer. Why go with an inferior and possible risky product? The comments made by epoxy purists feed on my uncertainty.
Hunting for some clarity, I email the Stevenson’s and gently ask if they still feel confident in their glue recommendation. In a friendly reply the next day, Pete Stevenson confirms he faith in plastic resin glue, with a useful caveat: “We’ve never had problems with the plastic resin glue for small boats like ours that are dry-sailed (kept on a trailer)” In other words, the glue works for boats that don’t live in the water. Well, that’s fine, because that’s exactly what I am building—a boat that is dry sailed.
I feel even better when I read what Dynamite Payson had to say about glues in his book, Instant Boatbuilding with Dynamite Payson. “I was brought up on the old-fashioned Weldwood plastic resin, and I never had any glue failures,” he wrote. “The epoxy glues available today are better still, and I’m all for them, but how much strength do you need?”
Once I understand the practical strengths and limitations of the product, I feel reassured and confidently order a 4.5 pound can of glue from my local hardware store.
As a caveat, both Pete Stevenson and Dynamite Payson also endorse some of the latest “squeeze bottle” glues (as I call them), such as Gorilla Glue and Titebond III, which are both rated as waterproof. I briefly consider taking this more radical path, but decided to take the slightly more conservative route by using the more tried and true product.