by GreenLake » Fri Oct 05, 2018 3:28 pm
If you have holes or cracks in the hull the approved repair would be to apply new laminate using fiberglass cloth and laminating epoxy.
In principle, for a "puncture" type damage that is small (1'4" or less) and well defined, you could use 3M High Strength Marine Filler.
But even there, the chances are that any impact that caused that puncture also damaged some of the surrounding laminate. You'd definitely would want to grind off any damaged laminate, and by that time you may have a shallow V depression around your hole which would then best be re-built with fresh laminate.
For cracks, the real issue is that they are under stress and you not only need to seal them but restore strength in that area. You start by grinding them out into shallow grooves - if any laminate that you expose looks "milky" you grind that away as well (intact laminate is clear - it will look dark).
Then you rebuild the laminate.
In an awkward corner, you may grind out the crack a bit, fill with 3M High Strength Marine Filler and then add a 2-3 layers of laminate as a "patch" over the inside, making sure your patch tapers in thickness by making each layer 1-2" narrower.
If you just "caulk" such cracks, they will likely work loose, or worse grow. Especially if near the centerboard.
I found a hole on my boat (looked like a bullet hole) that someone had caulked and then painted over. When I refinished the boat I was able to push that caulk right through. To imagine that any contact in that area could have reopened that hole at any time (well below the waterline) is a scary thought.
Laminating is not particularly difficult, if you haven't done it before you just need good instructions. Both West System and System Three offer publications on their websites that explain the basics. (SystemThree is widely stocked locally, so that's what I use, but West System, or MAS Epoxy are also reputable brands)
Keys to success for working with epoxy include careful measurement and thorough mixing. By all means, put a piece of wax paper on your workbench and laminate a trial piece. That will give you confidence and allow you to correct any mistakes. If the trial piece turns out well, keep it; you can later use it as a patch somewhere (if cured you need to sand it, but can then glue it in place with epoxy).
Good luck.
~ green ~ lake ~ ~