Insulating a Boat Hull – Part 2
I showed in the first video the tools I used to get the glue off of the hull. This glue is used in a lot of different construction and is a bane to the home remodeler. Even with the sealant remover and the steel wool, it required a *lot* of elbow grease. Thankfully I didn’t have much square footage to cover (compared to a house).
Once the vinyl, mold, and glue had been removed, I was left with a clean, white fiberglass hull, coated in epoxy gelcoat. Gelcoat is not a very good material to fiberglass to directly. The West Systems 103 fiberglass epoxy I use is designed to adhere much better to the polyester-resin fiberglass underneath the gelcoat. That meant I needed to grab my trusty rotary grinder and gently grind off the thin layer of gelcoat covering it. I needed to be extra-specially careful since my boat is in the water and much of the work I was doing was below the water line.I can’t stress enough how careful you need to be when grinding gelcoat. This was hands down the unhealthiest part of the project. Gelcoat turns into a super fine, electrically charged dust when ground off. That means it goes everywhere and coats everything evenly. It’s very hard to keep out of your eyes and mouth, even when wearing a dust mask and goggles. I ended up duct-taping my shop-vac to the handle of the grinder. I used some bilge-hose to create an ‘extension cord’ for the vacuum, so that it could be outside when running. Much of the gelcoat particles are fine enough that they come right out the other end of the vacuum. I also used a plastic drop-cloth to cordon off the V-berth from the rest of the boat. In hindsight, the drop-cloth was a great idea. Before grinding, I carefully measured out sixteen-inch intervals where I wanted to mount the hemlock ‘studs’. The strips of hemlock are ¾ inch wide, so I tried to grind away a 1 to 1.5 inch strip of gelcoat. That left room for plenty of overlap. Between manufacturing blemishes and the grinder, there were plenty of dips and grooves instead of a smooth surface. To deal with this, I laid down two layers of a 1-inch strip of fiberglass cloth between the hull and the hemlock. That worked well to fill in any gaps between the two.
There is also a slight curve to the hull. Most of the hemlock studs measured out to be twenty-one inches long. I ended up cutting them into three seven-inch pieces and fiberglassed them on separately. This made a much tighter fit to the hull. I used duct-tape to hold the hemlock in place while the epoxy cured. After it had hardened, I removed the tape and painted over the surface of the hemlock with another coat of fiberglass epoxy mixed with 403 particles. This coated the wood, sealing it, which will protect it from moisture and mold.
Before fiberglassing the hemlock strips to the hull, I mounted a T-nut in each piece. I had never worked with T-nuts before, but they were much easier to use than I expected. These will allow me to use machine bolts instead of screws for mounting, and will allow easy installation and removal of the upholstery.