I'm planning on painting the bottom and up the sides about 4" with a product called "Durabak". It's a truck bed liner that you can apply yourself. It goes on pretty thick and comes in a "Smooth" version. So when you consider that I'll be painting on a 1/8" of rubber, I'm not sure how smooth I need to get the bottom and the chines. I'm working on the premise that I want to completely fill the Biaxial fiberglass cloth and the 8 ounce fiberglass cloth on the bottom.
This photo shows the chine with the Biaxial cloth with 2 flow coats of epoxy. It still needs at least two more coats to be completely filled.
Tips for filling the Biaxial Cloth
A couple of things to mention. Epoxying a near vertical surface (the sides) is a PITA. There's a reason you glass and flow coat the sides before you stitch the boat together. You're working on a flat surface. Once the boat is stitched its a different ballgame. Now to do the chines and fill the Biaxial cloth you're dealing with a sloping side that is near vertical.
Its a little hard to see but the Biaxial Cloth is real close to being filled and it has been "faired" towards the center. I'll sand on it tomorrow and see how much more I need to do.
You flow coat the epoxy with a 3" foam roller and then tip it with a brush to smooth it out. The next thing you know is its running and dripping down. I masked off the sides to within 3 1/2" of the chine and am I glad I did. It would have been a mess. After each flow coat I have to pull the tape and then re-mask the sides before the next coat. So far I've put on two flow coats on the sides where Biaxial cloth is. I'm going smooth it out it by sanding with my half sheet sander and call it good for now.
I'm going to concentrate on "fairing" the bottom now and do the rest of the vertical chine when I flip the boat back over. That way it will be running down instead of all over the sides.
Fairing the Bottom
I used a 36" wide piece of Kevlar placed right down the middle. It's the yellow you see in the photo above and below. I then covered the entire hull will 8 ounce fiberglass. I added a strip of 8 ounce fiberglass on both edges where the Kevlar didn't reach the chines. So essentially I have two layers and then the Biaxial cloth on the chines. What has happened is that the fiberglass cloth is not entirely filled so it needs to be filled and the "faired". This means making it flat.
Here's a shot from the transom end. The whitish color on the bottom is where I "faired" it with the epoxy mixed with "Microballoons". I'm going to sand it tomorrow and see what I've got.
I mixed up a batch of epoxy and then added "microballoons". This is a filler than is easier to sand than wood dough. You mix the epoxy for about 2 1/2 to 3 minutes and than add the microballoons. It looks like "glass powder". I mixed it so that it still flowed pretty well, dumped it on the bottom and then used a squeegee to spread. it. You essentially, fill, let it harden, sand it, fill the low spots again, and keep going until it's either perfect of good enough to put truck bed liner on. I'm still trying to figure how flat that is. It will probably end up being pretty close to perfect. I'm using a Makita 7" Random Orbital Grinder/Sander to rough it it. Then I'll switch to the half sheet sander as it gets flatter. One nice thing is that you can use 80 grit and call it good. On the sides I'm taking it to 240.
So tomorrow will be a sanding day with maybe some more "fairing" to do. Whoppee!