Stem to Stern: Staying Power
There’s an old, half-rotten, wooden bench out behind the center shed where we place left-over catalyzed epoxy cups and buckets to cool off before we throw them in the dumpster. The crew is quite disciplined about it as a fire prevention measure. The reaction between the resin and the catalyst produces heat and, under the right conditions, it can start a fire. The plastic mixing cups we use will actually melt to that old bench from the heat generated within that reaction. We had a dumpster fire at our Riviera Beach location twenty years ago from dumping hot epoxy and we’ve been mindful of that ever since. I pitch the cold containers into the dumpster each morning when I open the doors and, on a recent morning, I got to thinking about good ol’ epoxy. What would the modern boatyard be without it?
Before the advent of epoxy in boat repair and construction, various adhesives were used to glue things together. The most common products used by shipwrights in the 1940’s and ‘50’s were resorcinol and urea-formaldehyde, marketed as Weldwood. These adhesives did a good job of holding things together and were relatively waterproof and durable when fully cured. They were both products which had first been used in aircraft construction and had migrated to boat building. The commercial use of epoxy, like many industrial materials, also originated in the aircraft/aerospace industry. Grumman had successfully pioneered its use for gluing aluminum parts together but in the 1950’s, it had not yet found acceptance in wooden boatbuilding. In that era, our boats were fastened with bronze or Monel Anchor-fast nails and screws and glued with resorcinol and Weldwood. In 1958, a customer by the name of George Mole ordered a 36-foot dayboat from us with a handshake agreement that the boat would be glued with epoxy resin. It was a roll of the dice, but a gamble that paid off. The adhesive strength of cured epoxy was found to be far superior to any previously known entity. In experimenting with the new glue, it was found to be suitable for fiberglass cloth saturation, producing much stronger and more durable FRP skins and components with a permanent adhesion to wood surfaces, unlike polyester resins which would release from a wooden substrate over time. Its gap-filling properties, when mixed with fumed silica (Cabosil) made it an excellent product for repairs and fairing. Unfortunately, the early epoxies were catalyzed with extremely toxic hardeners, which caused serious skin reactions on those who experimented with them. Over time, alternative hardeners were introduced which were more compatible for human contact in boatyard applications. Epoxy has now become a panacea in the workplace that no modern boatyard could exist without. The so-called “supply chain shortage” has made this abundantly clear to all of us in the industry.
In modern cold-molded construction, we use epoxy exclusively to fasten the boat together. The keelson is laminated 8/4 mahogany, scarfed, clamped and glued with epoxy. The stem is 18 to 24 layers of 5/16-inch mahogany, laminated and glued over a simple clamping jig on the mold loft floor. All the stringers and engine beds are scarfed and glued with epoxy as well, and each layer of planking is saturated with epoxy and clamped to the underlying layer with temporary tapping screws. The finished hull planking is glassed, inside and out, with epoxy saturated 1708 bi-ax and covered with multiple epoxy resin build ups. When the hull is complete, we have the boat equivalent to the automotive uni-body—a one piece, molded, mahogany-cored hull. We could never have hoped to achieve the unique strength and durability of cold-molded construction without epoxy.
Working with epoxy is an acquired skill. In my freshman year of boatbuilding, the journeymen shipwrights handed all the jobs they disliked to me. I considered this plebe system an unflattering but inevitable part of apprenticeship. Start at the bottom, and the only direction is up. Among those tasks was glassing the inside of integral fuel and water tanks. Having assigned that task to me, one of our veterans thought it might be fun to explain to the boss’s kid the wrong way to mix epoxy. There I went, two parts catalyst to one part resin (reverse ratio), glassing the entire inside of a 250-gallon water tank, baffles and all. Dad came to check on my project the next day and dressed me down, in no uncertain terms, insisting, in front of the entire crew, that achieving such an astronomical degree of stupidity proved, as he had long suspected, that I was the mailman’s progeny. It took me two days of scraping and soaking with lacquer thinner, working off the clock, to get that tank ready again for a proper mix. I did not rat out the veteran who laughed, unmercifully, for days on end. I soon learned that there actually was a use for epoxy intentionally mixed in reverse ratio. Before the industry conversion to polyurethane-based sealants and adhesives for glazing, my uncle discovered that “reverse” epoxy made a suitable, pliable, waterproof window caulking and we utilized that formula for many years before the introduction of 5200, Sika, Bostic and the like. A few months after my tank fiasco, someone filled the jokester’s toolbox with two-part expanding polyurethane insulating foam, one evening after work. The vandal was never identified. Who would do such a thing? I still don’t know for sure, but my money is on the mailman.
In the 64 years since our yard first experimented with it, epoxy has been packaged and sold to the consumer in all sorts of marketing schemes. Epoxy resin is epoxy resin. You can thin it, thicken it, offer a multitude of time and temperature specific catalysts, offer devices that mix in a pre-determined ratio, package it in snappy little kits and on and on but the basic chemistry of the resin is still the same. Around 40 years ago, a silver-tongued salesman approached us regarding a “New High-Tech” epoxy. It was “less toxic to the user, stronger in it’s adhesive properties, and sanded easier.” I was still green and had yet to achieve the practical apprehension and distaste for salesmen that are required to survive in business. I bit. We were sold the appropriate ratio pumps and several drums of resin and hardener. About half-way into a large project, we noticed things were beginning to come apart. The epoxy seemed to never fully cure, unlike our old reliable 510/ 855. Joints were moving and separating with changes in temperature and humidity. A nightmare unfolded in our busy shop and mayhem, coupled with chronic insomnia, descended upon us. We reached out to the “new glue” manufacturer and, of course, they blamed us for not mixing it correctly. Huh?! The bastards sold us the mixing pumps! They claimed we were the “only account” to have this problem. -Yeah, buddy. Never heard that before. As we frantically called around to our boatbuilding cronies in other yards, we discovered that this scenario had played out everywhere the product had been sold. Lesson learned: If it ain’t broke …! We went back to our old standard (now ID’d as 828/3055) epoxy and still use it exclusively to this day. I dare you to get me to change again.
Among the attributes of epoxy is one that is unrelated to the adhesion of materials. Epoxy is an excellent indicator of productivity and work ethic. As one observes the daily activity in the yard, it soon becomes obvious that the guys with the most glue on their work clothes are the hardest workers. When someone shows up clean and goes home clean, rest assured the pansy hasn’t done a damn thing all day. The neatnik pretty-boys are more concerned with presentation than productivity. The guys and gals that run to the office to ask Josee for a new shirt, halfway through the day because they are swimming in glue, are getting stuff done. Show me a man with work clothes that break when he bends, and I’ll show you a boatbuilder. Glue in his hair, glue on his shoes, semi-permanent blue fingernails from a mix of epoxy and bottom paint. The seats, floors, and steering wheel in his old truck are covered in epoxy from many a hard day’s work. The first thing he hears when he gets home is, “Take those shoes and clothes off in the garage before you put a toe in my clean house, fool. Last week you smeared glue on my great-grandmother’s Victorian English Brown Oak buffet as you walked in the front door. That cabinet has been in my family way longer than you and that will never change.” “Sorry, baby. Hey … you know … just like your family, that old thing has seen better days. Want me to epoxy it back together?”
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This article originally appeared in the June 2023 issue of Power & Motoryacht magazine.
Source: https://www.powerandmotoryacht.com/column/stem-to-stern-staying-power
