tbanzer

Afriend of mine has an area about 2 in buy 10 in that has some stress cracks on the front of one of his sponsons below the water line. The stress cracks looks like the gelcoat is starting to seperate from the fiberglass on this area. Any recomendations?

Velocity Vector

Once a stress crack begins, it can travel for great lengths. Sometimes a short one or two inch stress crack can travel the length of the boat. This is because once that fiberglass underneath has flexed, and once the gelcoat has given way, the bond has been broken. A separation has occurred. Then simple heat and sunlight is enough to cause that gelcoat to continue it's meandering course across the surface of your boat. Stress cracks can be successfully stopped however. The crack must be ground out thoroughly. It needs to be ground deep enough to reach good fiberglass (fiberglass that is not whited out or "shattered") and it needs to be ground out wide enough to reach the good fiberglass on either side and end. For voids, (a void is a place where the fiberglass had a low spot in it and the gelcoat didn't touch the fiberglass to bond with it) they need to be ground out and followed down through all the way till the end of the void is reached. Then new fiberglass must be applied. And of course followed up with the finishing touches of shaping and regelcoating. Normally this process will do away with the stress crack.
Sometimes a stress crack can reappear though, even if all the repair work was done properly. Sometimes if large surface areas are compromised underneath, in the fiberglass, stress cracks can reoccur. Though the portion you had fixed may be good and strong now, if that fiberglass surrounding the area is weakened and not properly wetted, then it is going to flex more than it should and problems are going to continue.