How To Re-Fiberglass A Boat Hull

Learning how to re-fiberglass a boat hull can be a real money saver if you're a boat owner. When doing your prelaunch inspection, you may notice a crack in the fiberglass that makes the boat unsafe for water travel. You can re-fiberglass your vessel and save your wallet the extensive fee of a professional. This is not to say that if you have a very extensive amount of damage, you should not seek the help of the professional. Only for small repairs it is perfectly acceptable to fix your damaged craft in the backyard under cover.

Things you'll need:

  • Skill saw or reciprocating saw
  • Wax removing cleaner
  • Sand paper
  • Two part or premixed fiberglass mix
  • Wood or plastic for backing of your hole
  1. Determine the damaged area. Once the damaged area is noted, you need to see how big the area really is. Using a plastic handle of a screwdriver, tap around the affected area. You will hear a light taping noise in the area where the damage is located. You will hear a healthy thudding noise where the area is healthy and secure. This sound will spread a little in the hull of the boat unlike the light tap which will make its presence known only in the area of the damage. Repeat this on the inside of the hull as well as outside the hull to make sure you have the fully affected area.
  2. Cut out the damaged area. Once you have located all the damage, it is time to cut the hole for the repair. Cut the area that was damaged out of the way, leaving only healthy edge. Try to cut your edge at a large bevel. This will make it easier to finish when you are patching. Work from the inside out, making the smaller hole inside the vessel. It would be better for the patch for the surface area where there is more pressure, such as the water against the hull, to be pushing against more surface then through the surface.
  3. De-wax and patch. Before you apply your resin patch, you need to make sure the surface is clean. A boat hull is always waxed. Using a solvent, wash the areas where the resin will be as well as around the area to ensure a strong hold. Once cleaned and dry, you're ready to apply your resin. Be sure to mix according to the specifications of the brand resin you have chosen for your project. If you choose a resin with a fiber installation, cut your fiber to layer in the hole of the hull. Use a backing on the inside of the boat hull and fill your hole with the resin until it is filled to the outside of the boat hull.

The hull of your boat is fiberglassed and ready to finish. Once the fiberglass is cured, you can sand it smooth and primer and paint the area to match the rest of the craft. Enjoy your newly repaired boat, knowing that your work is quality and strong. Make sure that depending on where the hole is located you use the right resin. Some resins will not mix well with the gel-coat on the bottom of the boat.


  • It is important to remember not to work out in direct sunlight. For this procedure, you must keep the boat out of direct sunlight for purpose of the fiberglass adhesion.
  • It is better to keep the boat under cover when being stored.
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