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ac505 04-25-2014 02:58 PM

Gelcoat repair question
The previous owner of my boat looks to have had an arguement with a dock. The result of this bring about 5 or 6 hairline cracks parallel to each other about a foot long in length just above the waterline on the starboard aft quarter. There is no flexing so I don't believe there is any structural damage. my plan is to open up the cracks and use some gelcoat filler. Given the cracks are quite long, I'm not too sure what to open up the cracks with. A dremel, angle grinder, use a router with a small bit or something else. Appreciate recommendations and experience.

lake weir skier 04-25-2014 04:44 PM

These are cracks created by impact to the surface and not scratches from movement along the surface?

If they are similar to scratches, opening up scratches for gelcoat is addressed 1 minute 50 seconds into this video. One suggestion looks like a can opener. The other suggestion - a Dremel -- looks like it has a Dremel silicon carbide grinding stone accessory. Iíve seen a similar Dremel accessory used by Andy Miller in his Boatworks Today videos.

How to repair Gelcoat Part 1 by TAP Plastics

I've got several tungsten carbide Dremel carving accessories for the preparation Iím doing for gelcoat repair, but Iím not repairing damage that is hairline. So far, Iíve used one of the structured tooth tungsten carbide accessories, which Dremel lists for fiberglass, but the structured tooth accessories might be too aggressive for opening up something that is hairline. I havenít tried it. You would have to be extremely careful.

ac505 04-25-2014 06:46 PM

Thanks, I'll check that video out in the morning.

I have one of these, hoping that I can set a shallow plunge cut and
open the cracks out.

AZDave 04-25-2014 08:18 PM

I have similar hairline cracks, between the grey gelcoat and the red sparkle gelcoat stripe around my boat. On the driver's side, just above the rub rail. Mine wont be that easy. 2 or 3 covering 2 feet in length.

CC2MC 04-25-2014 10:45 PM

I have repaired several hairline cracks, but not that long. The process should be the same, except I am guessing that took a little harder hit and I would check behind the center of the cracks, where it looks like it took the initial impact and make sure there is no splintering at all. More than likely you are okay. Here is the Dremel bit that I use to remove the cracked gel. You have to have a pretty steady hand or it can get away from you and take away more material than you planned.

mikeg205 04-26-2014 08:38 AM

A crack that long could indicate another underlying issue.

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ac505 04-28-2014 02:32 PM

sanded the "epicentre" of the cracks down today, it looks as if it is just the top layer of gel that is cracked, what beneath seems fine. I should get the dremel bit tomorrow so will press on with opening out the longer cracks. Will post a few pics when I get a chance.

ac505 04-29-2014 05:12 AM

for anybody interested, here is the progress. Cracks have been ground and sanded out. I need to pick up some acetone and then fill the hairline cracks, followed by building out the area that had been sanded back.

I've not yet decided which route to take. Options are
1. Epoxy filler, then get the area re-gelcoated professionally, or
2. Plastic Padding Gelcoat filler (which I think it polyester), which is white and can be sanded /polished, meaning no secondary gelcoating.

Any thoughts?

mikeg205 04-29-2014 09:52 AM

I would just use gel coat IMO. maybe a small amount faring compound. Hard to see in the picture is any of the glass ground down?

check the library and look at the video links

ac505 04-29-2014 01:56 PM

it looks as if the black is also gelcoat. (the boat is black and white). No cracks in the black fortunately.

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