Repair your boat hull with this 10 step boat repair hull patch project.
It doesn’t happen often, but once in a while, you get a ding, crack, or hole in the hull of your boat. Whether the damage is leaking or not, it’s important to fix these as soon as possible to keep them from getting bigger. Knowing the basics of boat repair is a must for boat owners.
There are two basic types of fiberglass boat repair:
Cosmetic Boat Repair – this is for damage that doesn’t go all the way through your hull, so you’re only patching one side.
Structural Boat Repair – This is for when the damage goes through the full thickness of the hull and you need to patch it on the inside and the outside. This is the type of boat repair we’re talking about today. For a cosmetic boat repair, the process is similar, but only applied to one side of the damaged area.
10 Step Boat Repair for Hull Damage
1. Mark the size of your repair area using the 12-to-1 rule. for each inch of thickness of your boat’s hull material, your repair area will need to extend by 12 inches in diameter (six inches from each side of the edge of the hole on the side of the hull where the damage is largest. Many boatswains advise a minimum repair area of 6 inches. From
2. Clean up the hole. Use an angle grinder to buff away the damaged fiberglass. Make the hole larger and taper the hull towards the hole so the inside edge is thinner than the res of the hull. Scrub the buffed surface with acetone. This will give you a rough, clean surface for your patch layers to stick to. Once it’s dry, you can move on to step 2.
3. Tape a piece of parchment paper over the hole on the inside of the hull for a backing. Use parchment paper instead of wax paper because it’s more heat resistant. Resin gets surprisingly hot while it’s curing. Use at least three layers of duct tape or gorilla tape to prevent it from melting and rippling from the heat. You want a smooth repair.
4. Apply a layer of fiberglass resin and fiberglass mat just large enough to cover the hole. Make sure your resin is fresh. If it’s more than a year old, it won’t cure as well. Apply the resin with a spatula or scraper. Let the resin cure until it’s hard. Tearing the mat instead of cutting it will give you a smoother edge when you’re finished.
5. Remove the parchment paper and tape backing. Your first layer is hard enough to stand on its own now.
6. Repeat step 3 on the inside of the hull.
7. Apply a layer of resin and fiberglass cloth to the outside of the hull. Fiberglass cloth is more tightly woven than fiberglass mat, making it stronger. The patch of cloth should be slightly bigger than the layer of fiberglass mat under it. Every time you add a layer, it should be slightly bigger than the one below it. Let the layer of cloth cure and repeat it on the other side.
8. Apply and cure two more layers of fiberglass mat on each side. Let each one cure fully before laying the next one.
9. Sand the repair area until it’s smooth with sandpaper. The best way to do this is to start with a coarse sandpaper and gradually work your way down to a smooth one. Spraying the surface with a light mixture of dish soap and water will make sanding much easier. It will lube the surface and keep your paper from clogging up.
10. Paint and polish the repair area. This step is optional, and is up to your own personal preference. Try to match the color of the paint on your boat as closely as possible, and polish in small circles with an orbital polisher.
Now you have a strong, smooth, nearly seamless boat repair and you can get back out on the water.