JEM Watercraft

I got the plans for my Trapper 15 earlier this month, the crazy weather only delayed the delivery by a few days. Put everything in a three ring binder and have read through several times.

Tomorrow, I borrow my buddies truck and drive to Gibsonville NC to pick up my 3 pieces of oukume plywood.

Here's where I need your collective brainpower.

Right now, it looks like Raka has the best prices on Epoxy / Fiberglass / Graphite / Hatches, but they have too many choices in the epoxy department. Thin / Medium / Thick resin, Slow / Medium / Fast / Non-Blushing cure hardener ...

I'm in Charlotte NC, my goal is to have this completed by May 17. Our average temperatures (Fahrenheit) in March average from the mid 30's to the mid 60's, in April from the mid 40's to the mid 70's. Spring temperatures here are about as predictable as a teenage girl's mood, with several days in the 70s, followed by a week of freezing.

I'll be building this boat in an un-heated garage, and would love to read your opinion on what combination epoxy resin / hardener I should get, an why?

Thanks in advance!

I've only ever used 1 brand of epoxy, mostly with slow part B but I have tried a faster part B and found that it caused a significant amount of blush. I suspect that the faster types have either more reactive or higher levels of amines and that they will always be more prone to blush than the slower types.

I also prefer the slower version because I am slow at wetting out. If you have no experience then I would tend to use slower because it gives you more working time. My climate is a little warmer than yours but I have seen posts somewhere showing people using epoxy in snowy areas - apparently it still goes off but it takes a lot longer. Someone else one here may have direct experience with that. If you have someone to help with the wet out then a faster system may be a safe bet.

Also bear in mind that if your build drags into summer or you have repairs to do sometime then you may have some hot days to cope with.

Makes perfect sense! Any advantages to the various thicknesses?

Thanks!

I've only ever used one thickness and am thinking of trying a different brand next time to get one thinner (more runny/lower viscosity). The advantage of this is that it gives easier wet out of the glass cloth. The disadvantage is that it runs out of joints more easily when used as a glue. This can be counteracted by addition of fibrous thickeners (eg woodflour).

Also, thinner is probably more suitable for cold weather - one that is already thick will be even thicker in lower temps. Some tutorials recommend warming both parts before mixing to give maximum flowability and this would be a good idea for your expected temperatures but don't overdo it. You just need to bring it up to maybe 80 or 90 F. It will cool down again but this should make it fluid enough for easy mixing and help the reaction to kick off.

Thanks Bob! I'll go thin, and take it slow. When I use the epoxy to actually glue something, like put my seats together, or attach the gunwales, I'll thicken with wood flour. I bet I can make a bigger mess than I do with TightBond III!

On another note on my experience with getting the okoume plywood. The stuff I got was not milled in the US, so it's not a true 8'x4' piece of plywood. It was about 3cm too long to fit in the bed of a F150 long bed pickup. Glad I also took tie down straps!