Tannin stain remover

[Oldlaxer1]

New owner here.  Been lurking around the forums for a while though and getting lots of tips from Stu.  I just bought a 1987 C34 that had a fair amount of tannin staining.  I'm not planning on hauling the boat until the end of the season but I wanted to try to clean her up a bit before then.  I realize Mary Kate ON_OFF works well for this application but I didn't want to use it while in the water.  It is a fairly strong acid and it is not recommended for use while in the water.  I found a product call Booyah Clean https://www.booyahclean.com/collections/booyah-clean-front-page-products and figured why not give it a try.  I used the boat soap sprayed at low pressure thru my pressure washer and then followed up with high pressure.  It cleaned the hull but didn't do much on the tannin stains. They recommended using it before the stain remover.  I then applied the stain remover with a little pump up garden sprayer from bow to stern.  I went back with the pressure washer to rinse and the stains were gone.  I'm really impressed.  It isn't cheap but it is EPA certified safe for direct release.  I have no affiliation with the company, just thought I'd pass along something that worked well for me.  I'm in the Chesapeake by the way. 

[Ken Juul]

If i remember correctly, lemon juice also works pretty well.  spray it on, light scrub, wash off.

[Ron Hill]

John : The best way to get that tannic acid stain off the hull is with FSR (Fiberglass Stain Remover).  You can get it at West or Defender.

Get a large container of the gel and put it on a white (soft scrub pad on a pole) and scrub the sides of the hull.  Let it set and then spray it off with water.  When dry, put a good coat of wax on the hull and you'll have a new looking C34.   

A few thoughts

[Stu Jackson]

Hi, John, nice to see you here.  FSR, it's a gel, easy to use.  I put it on the sponge side of a car window squeegie screwed onto a telescoping pole.  Then follow Ron's ideas. I agree, Mary Kate is dangerous; used it once but never again and that was in 2004.