Now that the hull is set in place, we can start working on solidifying it and assembling the remainder of the deck. To accomplish that, we will fill in the joints and seal the inside of the hull with epoxy. The filling of the joints is called “Fillet”. Along with this work, we will completely seal the inside of the hull with clear, two-part epoxy. The Fillet mix is made of the two-part epoxy mix and saw dust. The sawdust is added to allow the epoxy to thicken and “fill in” the joints. A side effect of this technique is that it makes the fillet mix cloudy, not clear. Since I’m going for a bright finish (that’s the clear coat where you can see the wood grain) I want to keep the fillets as small and neat as possible. I want them to be just in and over the joints. This also keeps the kayak lighter. In order to do this and keep a nice, clean look, I used painter’s tape.
The tape will keep the fillet in place over the joints and wires. After apply the fillet, I’ll immediately remove the painter’s tape and lay the fiberglass tape over the fillet. This will further strengthen the fill and bond that we need at these joints.
As soon as the tape is in place, I will apply a layer of clear epoxy over the tape and the remainder of the inside of the hull. This will fill in the weave in the tape and waterproof and further strengthen the kayak. Two coats of the
clear epoxy will be applied to inside.
The inside of the kayak is divided up into three parts, the front compartment, the middle area where passengers sit, and the back compartment. The best place to start is in either the front or rear compartment. These areas won’t be very visible on the finished product so it’s a great place for me to refine my fillet technique. I’ll complete these compartments first, and then finish on the passenger compartment.
When working on these areas, it’s important to realize that the fillet will harden up pretty quick. There’s not much extra time, so you want to get the fiberglass tape on the fillet as soon as you’ve applied in an area. The fiberglass tape must be absorbed into the fillet to create a good bond, which can only happen when it’s still wet. This should remain soft until the first layer of clear
epoxy is applied over the top. This combination will form a solid bond. The fillet and epoxy will harden pretty fast, so plan ahead and work in sections. I used small batches, usually about 3-4 pumps on the epoxy jugs and about ¼ cup of sawdust as a fix. I’d check the thickness and add in a little more sawdust as necessary. I’d need 2-3 of these batches to fill an end compartment. I used about 5-6 batches for the larger, middle compartment.
The mix for the fillet is about the consistency peanut butter. When I say this, I mean the thinner, all natural
kind. My first fillet mix was a bit too thick, and I quickly realized that I needed to thin it down a bit to get it to spread properly. Think frosting a cake. It needs to be thick enough to stay in place, especially on the upper seam, yet not too thick that it can spread properly over the entire joint surface between the painter’s tape.
It’s important to keep on the temporary beam stick in during this process. The kayak will not be frozen into shape until this step is completely finished and all epoxy is dried.
Make sure to allow enough time to complete each of the compartments. This is one of those steps where we need a good block of time. I used one
evening each for the front and back compartments. The middle compartment I reserved for a Saturday afternoon. If something hardens without having everything in place, you would no doubt need to sand a bunch and start over. One final point, the second coat of clear epoxy needs to be applied in a certain amount of time. For slow hardening, which is what used, you have 72 hours to get on the second coat. It’s
less for the medium and fast stuff. One last trick, use one of your lights to keep your epoxy nice and warm. It will pump easier and spread easier.
