I have an annoying azz stain on the back of the boat. noticed after I pulled the boat out of the shootout at LOTO. Usually I wipe the boat down immediately but the ramp was such a cluster puck at Tan Tar A Sunday morning, I said phuck it, and headed home, and washed the boat when we got home.

Its like a water stain line right where the water line would be. I got about 60% of it out, but the rest will not come out. I have tried wheel cleaner, toilet bowl cleaner, even 100% muratic acid (applied by hand, so I didn't get it on the Kplanes, or Hyrdo steering, and still can't get it out. Any Suggestions? I got the sides clean, its just that stern that has it.

also need to add, I have an aluminum I beam trailer, so I am leery about trying to spray some acid on it, and let it sit.
. I was very carfeful with the muratic acid, and put it on a rag, and then wiped the area first.

Maybe it's "base" isn't water or mineral, but oil. Might try a good degreaser or something like "Magic Eraser" from the grocery store (works good on interior too)

yep sounds like time for the Magic. I use them as a last resort because it is actually a micro abrasive and will need a light polish afterwards.

I would not use Magic Eraser on gel coat. It scratches. Last resort as GD said, then plan on polishing the scratches out.

Its probably oil based stain from floating with all the other boats. Try some Clorox Clean up.
Acids won't do anything to oil based stains.

Interesting thread, I was about to do a search. Saturday, I noticed some yellowing on and below the water line after pulling it out and giving the boat a quick wipe down. . I've never waxed the full bottom of the boat, but I've never had it yellow, and not wash off with soap and water. I guess the lake was unusually oily that day because several other boaters noticed the same thing. I too was about sick, as this boat has always been a really pretty white and easy to wash. I couldn't believe that one day on the water made such a stain.

I have had great succss with a product called "Slimy Grimy" when cleaning the whilte below the water line. I simply spray it on, let it sit a couple minutes while scrubbing with a brush and rinse it off. Take care though to cover your trailers as it will leave a mark.

Power One always takes the yellow stains off my boat. Just spray it on wait about a minute then hose it off. Check out Fountain of Youth products..

Would hand cleaner work....???????

Ok guys getting the chemist hat on!!

Rule of Thumb

Like dissolves like

so if you have an "organic" type of stain the best way to get the stain off will be with a similar organic -- that's why gasoline dissolves grease so well.

However, if you have an inorganic stain - e.g. water stain or dissolved minerals (rust) you need something that is inorganic like acid, Iron Out

From what you describe it sure sounds like an "oil film" on the water that your boat picked up. I would try - in a VERY SMALL area a little dab of Acetone - or if you have some fingernail polish remover -- BE CAREFUL WITH THAT STUFF -- it is EXTREMELY flammable and will harm a lot of stuff like your seats, rubber, paint. So if your boat is painted DON'T USE IT!!!


I have our boat on a lift and even using this I still get the yellow stain on the hull. I routinely hit the bottom with Iron Out -- My neighbor who hasn't cleaned the bottom of his boat - yellowing- for a number of years couldn't believe his eyes when I sprayed the bottom and watched the stains fall off -- the boat looks brand new!

All the best

Hope this helps

I typically avoid Walmart at all costs, but they stock "Shoreline Marine Hull Cleaner" which my neighbor talked me into trying. Biodegradable, and did a great job on lightly stained white bottom. You'll have to wax it again afterwords, but was pretty much wipe it on and spray off with hose.

On the Magic Eraser comments. Cleared up my mildew stained interior in no time. Then it started cracking in no time.... My upholstery guy loves them, made $300 off me recovering two seat bottoms a year later. Said they strip the protective coating off. Looks good till the sun drys out the material. Never tried them on gelcoat..