This hull cleaner arrived the day before my scheduled launch and I had already cleaned the hull with the remains of a Starbrite gel product that was very effective at cleaning most of the waterline stains on the hull even though I skimped on the amount of cleaner in order to complete the job. I tried the On/Off on those spots the had some remaining stain but it was completely ineffectual. Why use a very toxic product that requires special handling whose label does not disclose its ingredients, when there are other products out there that are much less expensive, more effective, and less toxic.

Used this to clean up a 10-year old mess of pine sap, mold, moss, mildew, scuff marks, and other grime. Incredible what it can do. Mostly just brush it on and rinse it off. Did use a scrub brush and orbital brush on the really bad stuff and molded-in non-slip. Used a full 1-qt bottle for all gelcoat above the water line on a 22-ft fiberglass sailboat. Ingredients are pretty harsh, pay attention to the personal protective equipment list.

Make sure you wash this off your boat trailer fast Use gloves and a good face mask when using The onle produt to use for the junk that grows in saltwater on the bottom off your boat For the scum line best stuff is slimey grimry no where near as toxic as on-off

have tried 3 other products befor this. none worked. this product is great

crei que iba a tener gue usarlo varias veces pero me equivoqe mi bote estuvo sin uso por mas de 4 años sucio y manchado increible despues de usarlo con spray me sorprendi lo facil y limpio gue quedo mi bote lo recomiendo si quieres tener tu bote limpio y no pasar trabajo Angel

Great product but not to be handled by those who are careless I and many others I have known have used this product with excellent results Makes stains disappear immediately . Very strong ,has an odor but I can deal with it for the results it provides

I have used On-Off to clean the entire hull and fiberglass decks. After long mooring times the hull comes clean with almost no effort. I wipe it on using a brush full strength on a dry hull. Use very small amounts in a pail and dry brush to apply. Let is rest on the hull for a few minutes, not to dry they dip your brush in water and begin to scrub. Add water to keep the area damp. Two or three light strokes and hose it off. Nothing works like On-Off and it's especially great at cleaning tuna blood that has dried on. Excellent for cleaning bilge areas but be careful to keep it off metal, it will remove galvanizing. Most important to use in a very well ventilated area. Not for a careless user.

My boat is a 1984 FourWinns(hull color is beige). It is used on a man-made lake in Pa. Every year when it's time to pull her out of the water for the season the hull is the color of dark roast coffee(blackish-brown). Last year when I stored my boat without the usual in-depth winterizing and cleaning I dreaded the spring clean up. This product saved me a week of hard work. Within seconds the hull was clean where ever the product was applied.ON-Off is one AMAZING product.

I sprayed this stuff on the bottom of my runabout and that dried on green film that just won't come off literally melted away even before I finished spraying. I then took a long handled soft brush and just washed it around and then rinsed and the bottom was clean as new. This may be the best product I have ever used as far as doing what it says it will do. READ AND FOLLOW THE DIRECTIONS, WEAR GLOVES AND DON'T GET IT ON YOUR SKIN. THIS STUFF IS SERIOUSLY STRONG.

i tried this stuff out cause my marina told me to i keep my boat docked in fresh water it is not bottom painted just has gel coat and i took the boat out and it was a disaster i thought i would never get it clean i tried using 3m rubbing compound to get it off and even with a buffing wheel and the strong compound it wouldn't budge took off a little but noting near what i wanted the whole bottom was done went to the store picked up a bottom what did i have to lose i sprayed it on the boat whole used windex top to spray it with and all of a sudden i seen smoke after the smoke i just seen the ick running down the hull i sprayed the bottom side the whole hull of the boat within minutes the boat looked like it just came out of the show room compounded and waxed it and wow made my boat look like brand new it burns ur hands so wear gloves you are dealing with acid and try not to breath any fumes in the stuff is strong but it is magic so just be amazed when u go to clean