Re: Good Deal or Not???
Kev, <br />In the event that the crack is though the reinforced wall of the hull, this is a structural problem. Like I said cracks tend to grow (think about your windshield when it gets cracked) looks fine at first then grows, and grows, etc. Fiber glass is a strong and relatively light weight building material consisting of glass fibers (for strenth) and a resin for a binding matrix to hold the glass fibers together. The resin itself is not very strong, just strong enough to hold and transmit forces from one fiber to the next etc. If the crack is all the way through, you have broken glass fibers the full length of the crack, making it easy for the next fiber in line to break when stressed. <br />One method to stop crack propagation is to drill a nice round hole at either end of the crack, centering a 1/4" or better" drill bit at either end of the crack. This would prevent the crack stresses on focusing on a few individual fibers while trying to grow, and spread it out over a nicely rounded area. Now two holes in your hull is not going to help much, you would then grind a trough from from the outside and fill holes and crack with gel coat type stuff. The structural repair would have to be from the inside (where you don't see it and it can be raised/widened around the crack). Sand Sand Sand (remove all gloss from around the crack) full length, and 2-3" or more all around the crack, clean up w/ acetone or similar non oily solvent, don't be afraid to remove some of the old reinforcement, you will be replacing it with better. Then patch with thin layers of woven type cloth (not chopped mat), as many layers as you can and as wide as you can. Picture a wide "band aid" bonding to either side of the crack to hold it together. Roll the saturated layers out with a squigy to reduce the resin content, remember resin is weak, a high glass content is preferrable for strength. Also I would use an epoxy type resin not polyester, Epoxies are stronger, although your boat is made of polyester epoxy will bond better. If you let your layers get hard between applications, you must sand down the areas before applying the next. You can't get the layers too thick, as the resin reacts with the hardener the chemical reaction can be quite violent "exotherm" and blow gas bubbles through your work "not preferred". To get the full chemical and physical strength from the epoxy, you might somehow post cure it after is sets up by itself with some external heat (say 200 -250F). If you supply me with a small section of your new laminate (20-50mg), I'll run a quick test on it and tell you if it is fully cured (Differential Scanning Calorimetry). I think you studied chemistry for a while, does any of this make sense? <br />I would think this is how a cracked hull repair would go, but I would ask someone in the business to see if they agree. I'd still bet your crack is superficial, if you don't see some larger circular cracking in the vacinity. <br /><br />I know this wasn't too short...but I hope you can use some of it.<br /><br />Remember, the only thing worse than sinking is catching fire!<br /><br />GrandX
