Gel Coat Repairs

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
I have 39 screw holes to fill where the flybridge cover used to attach and I also have some spider cracking to repair so I clicke on the article thinking "Great, here's how to do it."

Well, the article starts out well enough, talking about fiberglass and gelcoat, but quickly shifts to repairing with epoxy and ends with the statement "To complete the job, I prefer to paint the repaired area."

Not really what I was looking for.

I have a couple books and a DVD on order so I'll see what they have to say about it. In the meantime, I filled the holes with non-silicone caulk to keep the water out.

-- Edited by rwidman on Wednesday 12th of October 2011 06:06:36 AM
"To complete the job, I prefer to paint the repaired area."

For any amateur this IS the best concept.
Thinking about 39 screw holes....

Use a paper punch to make a hole in your favorite 2 or 3" masking tape.* Repeat 38 times.* This will make masking off the 39 sites easier.*

If the hole punch is too small, you might be able to run an electric drill bit through a role of tape and get any size hole you want, about one every 10" or so.

If using epoxy I paint the finish.

If using polester (or vinylester) resin or Bondo I gelcoat.

Just my preference from what I have read and practised.

I bought two or three booklets and a DVD on fiberglass and gelcoat repairs from I think they are West System products.

Anyway, they seem like a good start for anyone who wants to try their hand at repairs. I'm not saying one would be an expert after reading the booklets and watching the DVD, but it's a place to start.
It's matching the color that is the hard part. Did you ever see them match paint at the hardware Store?

A little red some blue a dash of yellow. Just to get white.

Repairing the hole is the big issue.**

The best I have seen is to drill out the hole thru to the inside. Next using a bent nail or an allan wrench wobble (Is this a word) out the hole. next tape the hole on the inside *then fill with resin to form a disk shaped plug under the fiber glass skin. Then redrill for what ever attachment you desire or sand smooth and match the color and apply gelcoat.

Like I said matching the color is the hard part. Trial and error is the only way to get it right.

You can't just use the factory color because of time and *UV.**It changes the origional color


-- Edited by skipperdude on Wednesday 19th of October 2011 01:03:27 PM
I have recently removed some fittings that were screwed to the flybridge outer fibreglass surface, leaving unsightly screw holes. to repair, I bought a can of white gelcoat (no chance to colour match, as the store had only one kind of "white"). Using a countersink bit, I cut away all of the fractured gelcoat around the screw holes, leaving a bevel. Mixed a small amount of gelcoat with a thickener, I had some "short fibre" stuff that worked well, and filled to level. That stuff shrunk a bit, so in some I gave it a second coat with thickener. In all, I gave them a coat, or two, of unthickened gelcoat. clean off with a razorblade or a sharpened scraper before the new gelcoat hardens completely. In some that was all I needed to do, as the razor edge was sharp enough to leave a shiny surface. In others, a little samding with 2000 wet/dry, then polish. Mostly they have disappeared, unless you know exactly where to look, and your colour discrimination is good enough to see the difference. On a 31 yr old surface, I am happy with the results. Takes some time, but well worth the effort.* Didn't use more than 10% of the gelcoat in the smallest can I could buy, so lots left for any other projects that come along before it hardens up in the can.

-- Edited by koliver on Thursday 10th of November 2011 09:57:51 AM
Thanks KOliver. I think I'm going to try that on my 1986 white? Gel coat. ?

Sent from my iPad using Trawler Forum
" (no chance to colour match, as the store had only one kind of "white")"

Oil paint pigment can be added to change color , but the color of gel coat changes as it dries , and there is a color change in old gel coat that is hard to match.

It tales a true artist with loads of experience to get a near color match.

Off color pimples may look better than raw holes , and stop a leak.
I've found a few pieces of clear mylar helpful for gelcoat patches.

Mix the gelcoat on a piece placed over the existing gelcoat and you can easily see how close the colors match.

Also cut a piece slightly larger than the patch area and hinge it w a piece of masking tape. After filling and leveling the new GC place the mylar over the new get the smooth surface finish of the mylar transferred to the patch.

If needed finish w 3000grit wet&dry then compound.
Should you use mold release or wax on the mylar so it doesn't stick?
Or is mylar slick enough?
Should you use mold release or wax on the mylar so it doesn't stick?
Or is mylar slick enough?

I never had to add comes off clean
My boat is a light beige or almond, not white. As it sits in the sun, the color fades and it's pretty obvious where the surface is protected from the sun. To get the best match if you are making a repair, you should wet sand, then compound the area. Try to match that.

Of course, the repaired area will not be a good match until you've wet sanded and compounded the entire boat.
Top Bottom