After MUCH too long a time, some personal issues have started to clear up and I finally got a chance to start building. I'm still waiting to be able to afford the materials for a Weekender, but I've started building a Mini-Cup. I've been at it for about a week, even in the killer Phoenix heat, and I'm having a ball. I have the hull bottom and cockpit together, and I'm about to put together the daggerboard and mast box, but here's where I have a question.
The plans call for waterproof glue on the interior of the daggerboard box. Obviously, epoxy would be a better choice, but I'm wondering how much time I would have to apply it in 105 degree heat.
Would I get longer working time with polyester resin? I know polyester resin allows more moisture absorption, but hey... it's Arizona, and the boat would spend most of its time out of the water.
What do you all think?
Use 209 hardener with the 105 resin and you'll get about a half hour working time, maybe a little less in 105 heat. Of course doing your epoxy work in the very early morning or evening will increase working times considerably. If you use 205 in that heat, it'll kick off before you get it fully mixed. 206 will give you a few minutes of working time. You also can work with a "cool can", which is a pan of ice water that the mixed epoxy rests in (another container), which will delay the reaction until you have it applied.
Polyester on wood just plain sucks. It's not the moisture absorption thing as much as it's ability to stay stuck to wood. Even the guys that regularly use it on wood have to stable the cloth down, just to improve it's adhesion. Lastly if you mix the epoxy with some fillers (silica, milled fibers, etc.) you can improve abrasion resistance inside the case, which will take a lot of abuse from the board. Log onto westsystem.com and systemthree.com and download their user's guides, to get an idea what fillers to use for what reasons, techniques and product application.
I mixed graphite with epoxy and coated the inside of the dagger board box as well as the inside of the rudder and mast box. You don't have to worry about sunlight in the daggerboard box so the epoxy with whatever won't break down from uv. The graphite gave the epoxy mix a glossy black look. Here's an old picture of what the epoxy and graphite looked like on the interior of pieces of the rudder and daggeroard:
Thank you for the information, Paul. What you suggest always seems to make so much sense I always wonder why I didn't think of it in the first place.
Terry, those pieces are much too beautiful to hide away inside a box where they will never be seen.
Thank you both for the help