Recently, we blogged about the preparatory steps that you need to take before you begin to mend a crack in your fiberglass boat's hull. This is a process that every boat owner with a fiberglass vessel should understand, as you don't want to be stuck out in the middle of the ocean with a breach that you can't fix. This would put you and your passengers at risk.
Once you've prepared the area that is cracked for repair, you'll need to begin to apply glass fabric in alternating layers between 1 1/2-ounce mat and 6-ounce cloth. In between each layer, you'll apply a coating of resin that will hold the materials together. The first layer should be placed on top of a thin application of Gelcoat, which helps to hold the subsequent layers in place.
Generally speaking, it's recommended that you apply one layer of cloth and mat for every 1/32 of an inch of hull thickness. In other words, if your hull is a half inch thick, you would want to apply 16 layers of fiberglass before putting on the finish.
BoatUS, a boating resource, suggests using polyester or vinylester resin when you are patching a hole that is above the water's surface. For cracks that are underwater, you should use epoxy instead.
Of course, it's always preferable to not find yourself in a position where you have to fix your hull at all, which means you'll want to do a good job of anticipating any underwater hazards that might cause a breach. The best way to do this is to equip your boat with a marine transducer and other marine electronics that can give you surface and water column information in real time. For more information, check out the latest navigation products from ePal!