A Beautiful, Terrible Romance: Fiberglass & Epoxy
Of the many, many things I have underestimated in this project, absolutely none held a candle to my naiveté of fiberglassing. I have learned more about resin chemistry, thermal behaviors of curing, and properties of various fiberglass weave patterns than I ever intended to know. But the number one lesson I’ve learned, and that which I wish to pass along to you is this:
Don’t ever fiberglass anything. Unless you really, really need to. And even then, are you sure? Maybe you don’t need to.
Part of me is kidding. This is a fascinating material science, an incredibly enabling technology, with a million applications. Not to get all Carl Sagan-y, but it’s a miracle humans can do this.
But part of me also has an aching back, and epoxy burns on my wrists and arms. I’ve destroyed unreasonable amounts of clothing, and spent about 8 more weekends on this than I thought I would. I’ve purchased nearly 10 gallons of expensive resin and glass, and lost a lot of sleep worrying about cures and fiberglass placement.
Also, side note, friends disappear like Natty Lights at a frat party when you ask “Hey, wanna sand fiberglass with me this weekend?”
But let’s back up.
It’s a Miracle Humans Can Do This
For millenia, boats were really heavy. The structural load water exerts on hulls is immense. What’s more, water being the god molecule it is, finds ways through pretty much everything. Salt water destroys all. Plus, gold is heavy, Sperm whales are powerful, waves are big, and Phoenicians enjoyed battle ramming. For all these reasons and more, it was historically imprudent to venture beyond the coastline without two or three inches of dense lumber between you and Moby Dick.
A galleon could easily weigh 1,000 tons. You don’t have to be a naval engineer to realize this meant boats were a slow, expensive, and resource-intensive endeavor.
But, being the creative little monkeys we are, eventually we found a better way. Like most absurd material advances, a couple of discoveries in the 1930s changed everything: First, some Swiss/German scientists (typical) realized that mixing certain polyepoxides with polyfunctional amines, acids, phenols, or alcohols (obviously) resulted in new, interesting plastics we now call epoxy. At nearly the exact same time, some Americans found a way to mass-produce fiberglass, which had been discovered just a few decades earlier.
The real miracle was when you combined the two. Fiberglass is literally just glass strands, woven into a fabric material. In the woven direction, its tensile strength is pretty incredible. And if you soak it in epoxy resin and let the two cure together, you get a waterproof material stronger than many metals, much lighter, and easier to mold.
Immediately, people realized this could dramatically change boat building.
So Why Are You Whining About It?
Great question. Because it’s a f***ing nightmare to work with.
Not in the 1930’s, “walking on skyscraper beams without a harness” sense of scary. But very much in the 2018, “why is my craft coffee so hot?” sense. It’s a real-world miracle, and a first-world daunting task.
The resin transforms from liquid to solid plastic in a few hours. Once the reaction starts, there is no stop button. Every 10–30 minutes, the viscosity doubles until it’s rock hard. While you’re working, you can feel it starting to fight you. It gets stickier and stickier, and harder to work with. And you really shouldn’t get it on your skin.
Adding to the fun is the exothermic nature of the reaction (it gives off heat). The curing speed is proportional to ambient temperature. Meaning the hotter it gets, the faster it cures. The faster it cures, the hotter it gets. A runaway reaction can occur that steams, melts containers, burns skins, or even catches fire. One of our first batches nearly did this.
Then there’s the fiberglass. Glass has impressive tensile strength, but shatters if bent excessively. This applies to the cloth version too. You have to be very delicate; fold the cloth too much and unknowingly compromise its strength. It can completely fall apart in your hands if over-worked. Most cloths are difficult to form to angled geometries without creating bubbles like a poorly tinted car window. And as the resin starts heating up and getting sticky, it gets even more frustrating. Your brain realizes the situation is getting worse every minute. You panic. That doesn’t help. Bubbles form underneath; you try to push them out and distort the mat even more. You swear at the gods; that doesn’t help either.
The next day, and after a long shower that still doesn’t get all the resin off, you return to your work to see how poorly it cured, bubbles everywhere. Fixing it means sanding it, and this is where the worst of the monsters rears its head: Sanding glass puts billions of tiny shards in the air for you to breathe, absorb into your eyeballs, and every pore of your skin and clothing. “The Itchies” persist for hours or days.
That Sounds Terrible
Yep, but it’s worth it. The wood seals into a waterproof, durable layer with significant rot protection and strength, and means you build a strong boat with less wood.
That said, there is a balance to be struck. While most boats today are almost entirely made of fiberglass, there’s an argument to be made that it’s a lot more enjoyable to spend your time woodworking, not fiberglassing. In order to match the strength you get for free with an extra 30–50% wood thickness, you spend too much time sweating with toxic chemicals. The costs roughly cancel out, and fiberglassing takes way more time. You don’t need to build a galleon, but a sturdy wood boat with minimal fiberglass is much more enjoyable to build (and pleasing to look at) than a lightweight boat with substantial fiberglass.
Quick Status Update
So fiberglassing has been rough. However, I’ve made a ton of progress. I’ll save some of it for future blog posts, but a few quick highlights:
I secured the main seating to the hull! This was made difficult by the hull having bowed outwards by more than an inch. So I used cam straps to literally crank the hull back into position and then fiberglassed in place to hold. The parts of the seats that will be visible look pretty nice after several layers of fiberglass and gel coats.
I bought a 15 horsepower outboard motor, and we can secure it to the stern (after some hilarious adjustments). I’ve got an entire post to write up about the propulsion system; the physics behind hull planing, the wave dangers presented by a low stern, and how we’ll deal with water flooding into the boat if/when it happens.
I’ve started priming the hull for painting, too. It’s really starting to come together. I’ll hold off sharing those photos for now, but finish today with what the boat looked like with all the wooden parts in place. Till next time!
