Stains at the waterline on fiberglass boat

michael13

michael13

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I know this is not an auto detailing question per se, but does anyone have any suggestions on how to remove stains at the waterline from the gel coat of a fiberglass boat?
 
Try DG 501 first and then get more aggressive if need be!
 
I use a wool pad, and some 1000 grit marine compound. Does the trick every time. Just be prepared to put a little muscle into it.
 
Did you spray the boat down with degreaser first? Usually roll off will take most of it off. Otherwise a wool pad and compound get rid of it quick.
 
How old is the boat and how long has the stain been there? If it's years and years of staining your gonna need a marine compound, if your new to this I would recommend meg's marine line 1 step compound, works great and easy on/off with good results even by hand
 
gt08vapor said:
You do not need a marine compuond, Any will work
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True you don't "need" a marine compound but depending on how long that stains been there it will speed the process up, generally marine compounds have more cut then automotive, but something like menzerna pg or xmt #4, megs 105 is decent if that's all you have
 
A little more information please!
What kind of stain? Metallic, algae or just lack of maintenance as the boat sat in the water? Salt water or fresh? Is the boat out of the water on a trailer or cradle?
If its metallic there is a product called FSR (Fiberglass Stain Remover) you can get at any marine store (I have not looked for it here) that will take it off chemically in about 20 minutes. Be carefull and wash your hands a lot. It will take the hide off. Have not tried AOL for anything drastic but it does work
If its a plant stain vs plant life I just used the Collinite #920 cleaner with decent results. Plant life takes a scraper or green pad first.
If the boat is out of the water, well and good.
If you are going to try it in the water, safety first! Things powered by electricity seem to have a natural affinity for mixing with water and producing the smell of bad BBQ, and it always takes less than you think. There are also a group of people around who frown about mixing certain chemicals with public water supplies.
Fiberglass gel coat is generally pretty resistant to deep stains unless you have other issues. Like your car, tread lightly first. You can damage the gelcoat and then it gets ugly
 
Thank you for the product recommendations.

Yes, I sprayed the boat down with degreaser. It removed some of the staining, but not all of it.

The boat is kept in fresh water and is not bottom painted.

The boat is a 1987 Crestliner Nordic. The staining was not visible when we bought the boat 1 year ago. Since then, it was kept in the water 1 entire season. This is where the staining came from The staining has gotten progressively more obvious as we now keep the boat on a trailer.

I believe the staining to be from algae and other fresh water plant life, and contaminants.
 
Sounds like you just have bottom growth. That is what the paint is for, to keep that to a minimum.
When it is in the water for extended periods you need to hire a diver to go under and clean it with a scotch pad. I pay a dollar a foot twice a month in saltwater.
Since it is out of the water, park it somewhere that you will not mind the stain on the ground after and start scraping (plastic bondo trowels work ok, not metal, do not gouge the gel) Just get the film off. Then pull out your machine and the cleaner. This will cost you a pad or two cause they will never be clean again.
If it is something else let us know
 
ig2dx2 said:
Marykate On Off Hull Cleaner
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This thread was made before I even joined AGO.

But, having worked in the marine industry for over 30 years, this is the correct answer.

And without sounding like an a$$h*le, all of the suggestions offered on page one of this thread are laughable at best.
 
I'd definitely put some anti-fouling paint on her ... West Marine and Pettit both make decent products for this.
 
57Rambler said:
I'd definitely put some anti-fouling paint on her ... West Marine and Pettit both make decent products for this.
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WM and Pettit are far inferior to Interlux products. The price reflects it. (Akin to buying NuFinish vs. Collinite).

But the OP was asking about stains right above the waterline. That browning that affects the gelcoat just above. ;)
 
You are right about the previous answers being laughable. I was reading thru the old post when I saw the question and had to chime in. Wipe on rinse off and done! No compounding or buffing to remove the dreaded waterline moustache, discoloration or stains. Marykate is like magic. I have used it on topside stains too. Nothing beats Marykate for removing stains from tree leaves in gelcoat. It also removes soap scum on shower tiles and fiberglass shower surrounds. It will remove hard water deposits in toilets and on glass too. For anyone that isn’t familiar with Marykate On Off Hull Cleaner, wear gloves and don’t get it on anything metal!
 
The Megs. Marine and RV all in one really does a nice job with a DA with a orange (lesser may be better or yellow pad) If that does not do it, go to a wool pad to remove. or better yet a Rotary polisher. Just remember if you use a Rotary, go back over and get rid of the marring with the DA Polisher and a white for polishing and a black pad for waxing. good luck. T
 
Muriatic acid and proper PPE. Bar keepers friend/ oxalic acid for non skid.
 
Before you spend any money on a fiberglass dedicated product, try toilet bowl cleaner, like SnoBowl, it worked on my white hull for years.
 
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