Yellow /Brown Stain above Waterline
 

What is that yellow/brown stain that I get every year on the gelcoat, right above the antifouling paint ? Every season it appears.

My water line could be raised for sure, but the water line is always above the brine, albeit only 1" or so.

My theory is that the 42 year old gelcoat is porous - even though I wax it well, it allows for the stain. It is easily removed with muriatic acid but I'd like to prevent it in the first place.

Ideas ?

Happens to all boats old and new here in FL. Its more than likely not porous gel coat just high mineral contents in the water like iron or tannin from estuaries. LI sound is not the cleanest body of water either!! I use a very cheep product called "Pink Stuff" A whole 1 gallon jug is less than $10. You can find it at your local paint store. It is used by painters to remove rust prior to painting homes. I dilute it 50% with water. I always use a good polish on the hull after. Keeps the staining gone a bit longer

Davis FSR
 

Pink Stuff?!!? ...Better yet buy the marine product made for this kind of thing... (though im sure you have luck with the pink stuff.

Use Davis FSR (Fiberglass Stain Remover). Its a gel that you brush on with a china bristle when the boat is out of the water and then wash off with a hose. Voila.

The cleaning is the easy part - I want to try to avoid it...

Sorry, you'll have to keep her on the trailer then.