Tag Archives: gelcoat repair

Gelcoat Repair

The decision to upgrade our old Nexus Multi transducers and display to a new Raymarine system meant that it was time to fill and repair two holes in the cabin house in preparation for the new instrument cluster. Except for a small repair to the topsides a few years ago, I have very little experience working with gelcoat so I was looking forward to learning something new.


The old Nexus (and the newer Raymarine autopilot control).

After removing the two instrument displays and the Lexan base, I scraped away the sealant and used a 6″ RO sander to create a bevel around both holes to provide more surface area for the fiberglass patches I would add later. (I didn’t bring my camera, so I don’t have any pictures of this process). I cleaned the area well with acetone to remove any residue and dust. Since I had access to the back of the holes from inside the cabin, I sealed the back side of the holes with several strips of duct tape. With the holes ready to be filled, I cut several round patches (the first large enough to cover the outer edge of the bevel, the smallest the size of the hole) out of fiberglass cloth and two layers of biaxial cloth for extra thickness. I then wetted them out thoroughly with West System epoxy and began applying the laminations, leaving them overnight to cure.

The following morning I rinsed the area with fresh water and scrubbed the repair with a Scotch-brite pad to remove any amine blush before giving the area a light sanding with 80 grit. I followed the sanding with another rinse and acetone wash, then mixed up epoxy with microlight fairing compound and spread it on. Once the area had cured, another water rinse and acetone wipe, more sanding, and another rinse and cleaning with acetone. The area was now ready for gelcoat.

Fairing compound

Microlight fairing compound over the laminations.


View of the back side of fiberglassed holes.

Sanded and faired

Sanded and faired

Microlight sanded and faired, ready for gelcoat.

I used Hi-Bond white gelcoat with wax to finish the repair. Ariel’s gelcoat color is a slightly creamy white, and the Hi-Bond white is a very cool blue. I tried adding brown to tone down the gelcoat, but only succeeded in producing a mauve sort of color that was unacceptable. The second attempt combined red and yellow to create orange. The orange pulled down the blue and created the slightly creamy white I needed. I applied a coat of my tinted and catalyzed gelcoat with a foam brush and left it to cure overnight. The next day I water rinsed and acetone washed the area to remove the wax that comes to the surface and causes the gelcoat to cure. That was followed by a light sanding and a second color-matched batch of gelcoat to fill a few low spots and provide better coverage. Satisfied with the color and coverage, I sanded the cured gelcoat with 200 grit to knock down the high spots, then began wet sanding with 400, 600, 800, and finally 1500 grit paper. I still need to compound, polish and wax the area, but it already looks better than Ariel’s original gelcoat!

New gelcoat

New gelcoat

Overall, I’m quite pleased with the result. There are a few imperfections, but they’re probably only visible to me. Now it’s time to add the new instrument displays. Nothing like cutting new holes in freshly repaired ‘glass!

*Update*: The instruments are in!

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