Gel Coat Stains Keep Coming Back

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
Striper15
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Joined: Tue Oct 20, 2015 7:42 am

Gel Coat Stains Keep Coming Back

Postby Striper15 » Tue Oct 20, 2015 7:51 am

To remove stains from my boat's gel coat layer, I have been using Davis FSR stain remover, and it works great. Problem is the stains keep coming back, seemingly in the same spots, after I return from each trip. Initially, I used the FSR followed by Meguire's marine polish. The stains are primarily at the waterline and bottom of the boat and are a golden brown in color. My boat is a 1982 15-foot red dot [work boat layup] hull. Any ideas?

jimh
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Re: Gelcoat Stains Keep Coming Back

Postby jimh » Tue Oct 20, 2015 10:34 am

Remove the stains again, using your preferred method. Then polish the gel coat in the stained area. This should reduce the porosity of the gel coat in that area. Then apply several coats of a good boat hull paste wax. Collinite Fleet Wax is a good choice. This will create a waterproof barrier in the area of the stains, and keep water from soaking into the gel coat layer. On a boat with a good layer of wax on the gel coat, most water-borne stains should not get much traction on the gel coat and should wipe off easily with a bit of water and mild soap. (Of course, much of that depends on the water your boat is operating in.)

Then continue to use the boat. If the stains reappear, I suspect they are coming from inside the hull, not from something external to the hull.

Striper15
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Re: Gel Coat Stains Keep Coming Back

Postby Striper15 » Tue Oct 20, 2015 4:04 pm

Thanks, Jim. I'll give the paste wax a try. I assume that if it is coming from the inside could only mean one thing, water in the hull.

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Dutchman
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Re: Gel Coat Stains Keep Coming Back

Postby Dutchman » Wed Oct 21, 2015 9:36 am

Stripper15 try the stuff offered by Aurora marine and "Ask the Skipper" I have used many of their offerings with good success. I used their waterline cleaner on one of my sailboats and it did what they said it would. The Boat Scrub also works great.
Just a suggestion but ask them and they'll tell you in a private email.
https://www.auroramarine.com/store/waterline-stain-remover.html
EJO
"Clumsy Cleat"look up what it means
50th edition 2008 Montauk 150, w/60HP Mercury Bigfoot

flymo
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Re: Gel Coat Stains Keep Coming Back

Postby flymo » Thu Oct 22, 2015 3:05 pm

My sister-in-law has the same problem on her 18 - recurring stains, light brown in color. Unfortunately the diagnosis, from a local shop which restores a lot of Whalers, is that the cause is indeed the problem you cite, water in the hull, combined with relatively thin, old gelcoat. A coat of wax will not hurt any, but if the staining is coming from the inside, it won't help much either.

I hope that's not it, but it sounds like the same situation.

F
Last edited by flymo on Mon Feb 08, 2016 7:00 pm, edited 1 time in total.

Striper15
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Joined: Tue Oct 20, 2015 7:42 am

Re: Gel Coat Stains Keep Coming Back

Postby Striper15 » Thu Oct 22, 2015 8:44 pm

Yea Fly, that's what I'm afraid of. I wouldn't think that the gelcoat is thin since this is a red dot "commercial" hull and is supposed to have thicker gelcoat. Thanks for the response.

Dutch, I contacted Aurora and waiting for their reply. Thanks

Striper15
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Re: Gel Coat Stains Keep Coming Back

Postby Striper15 » Fri Oct 23, 2015 4:32 pm

Here is the response I got back from Aurora.

Remove the stains with Waterline Stain Remover. Deep clean and prep the fiberglass with Boat Scrub and a Marine Power Mitt. Apply 2 coats of VS721. Wipe any slime off the bottom when you can and the bottom should stay clean.

The VS721 will reduce the friction on the hull so you should get better acceleration, possibly better top end speed and better fuel economy. the boat will also be easier to haul and launch from the trailer. Make sure that the boat is properly tied down on the trailer.

billybhoy
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Re: Gel Coat Stains Keep Coming Back

Postby billybhoy » Sat Oct 24, 2015 1:16 am

The active ingredient in most hull cleaners that are any good is Oxalic acid. I bought it raw, experimented and now it cleans the hull in a jiffy. Dirt cheap as well. I use an old military gas mask, rubber gloves and off I go.

jimh
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Re: Gel Coat Stains Keep Coming Back

Postby jimh » Sat Oct 24, 2015 1:37 pm

The gel coat layer in a Boston Whaler hull built to workboat specifications (or a red dot hull) is not likely to be particularly thicker than in a regular hull. The portion of a hull built to workboat specification that is thicker are the layers underlying the gel coat layer. A thick layer of gel coat is generally not at all desirable because it leads to stress cracking.

Binkster
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Re: Gel Coat Stains Keep Coming Back

Postby Binkster » Tue Nov 10, 2015 1:04 pm

Tape off a section that is stained, about one-inch-square. Sand off the stain using 500-grit wet or dry sandpaper. Then go to 100- grit, 150- grit, and then 2000-grit. The sanded spot should now look like the rest of the hull. Remove tape. Now see if the stain comes back in the sanded section. I doubt it. If it is good, then sand out the whole stain in the same manner. You could go up to 2500-grit and 3000-grit, and the boat will shine without wax.

rich