Hello all, I am making a IOM and this weekend finished making the fin box. I made the fin box with a flange top and bottom I was going to epoxy the box down to the hull but then I thought I could use CA glue. Is Ca glue water proof or will it lift after a days sailing?
Isn’t CA glue great?
But in my experience it is brittle and when I need to get it off it will finally pop away from resined glass. Not sure if its waterproof but since that area of the boat gets stress and some flex, I would think the danger would be some hair-line separtion thus a leak. My vote would be for epoxy - better bond, stronger and slightly flexible.
CA glue is entirely waterproof. You may use it with confidence in many joining applications. It is not the best for filling joint misfits or other open areas.
I would not use it on a fin box. As Yar says, it is brittle and the fin box is the most highly stressed element in the whole boat. Use epoxy for that join. Also a layer or two of glass tape is good insurance for reinforcing the join at the garboard area. The box will have to withstand the loading of a 5+ pound bulb hanging out on a long lever arm (fin). Make the box and its attachment in an uncompromising way. We are dealing with a lever arm that can generate more than 5 foot pounds of static force. Further than that, there will be dynamic loads, like a sudden gust or when you hit something (say a port tacker). If the boat stops suddenly the bulb will do its damndest to keep going, sort of like a sledge hammer.
If you are planking, it is tempting to use CA. The planks will be secure enough but the Ca that seeps out along the edges is difficult to sand evenly with the planks. For that you can use Titebond 2 or Titebond 3. It is cheap, sufficiently waterproof and after application, (before it hardens) wipe of the excess with a wet rag. Thereafter the assembly is easier to sand and make fair.