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How to prep Fiberglass Boat Bottom and apply VS721?


Jim Johnson asked:

I have a 22′ deck boat. I would like to try VS721 bottom coat on it. My question is how much do I need to purchase and the same for anything else I need to prep for it? From what I’ve read, I should also get Boat scrub. Is there anything else needed to make the VS721 last the season?
Also, can you put VS721 on by hand or would you recommend using a buffer?


For your convenience, I’ve highlighted the hyperlinks. Click on the hyperlink to get more information about the selected product.

Coverage of VS721 is about 400 sq. ft. and you need 2 coats. One bottle is usually enough to protect a 24 ft. boat. To prep the bottom, you will need 1 bottle of Boat Scrub and a Marine Power Mitt.

Make sure that the bottom is free of marine fouling and staining. I assume that your deck boat is fiberglass so the best product to remove fouling is Green Genie and water stain is Waterline Stain Remover. Next give it a good scrubbing with Boat Scrub, rinse it clean and allow it to dry thoroughly. Apply VS721 with a damp sponge and when it starts to haze up, wipe off the haze with an old terry towel or microfiber cloth. After 24 hours and within 2 weeks, apply a 2nd coat. Allow the VS721 to cure for a minimum of 48 hours before launching the boat.

For regular maintenance and to keep the bottom free of marine fouling, wipe the slime off the bottom from time to time as it begins to form. Slime is bacteria in water and it’s food for algae and other marine organisms, so if there is no slime, there will be no bio-fouling.

VS721 will seal the pores in the gelcoat to prevent osmosis blistering, it will reduce the friction on the hull which will give you better performance, reduce fuel consumption and make hauling and launching your boat much easier.

If your boat is on a trailer, here’s a link to the Ask the Skipper Blog that shows you how to lift the boat up off the trailer so you can get under the bunks and protect the entire bottom: https://www.auroramarine.com/main/ask-the-skipper/getting-under-the-trailer-bunks-to-clean-the-boat-bottom/

Thanks for your question,

Captain Aurora
Richard Kittar

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