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How to Protect against Waterline Staining with VS721


Brian Rush from Aurora Canvas Asked the following question:

We have been asked the following question from a customer. Please advise us with the proper response.

I have purchased a number of Aurora products from you in the past. I’ve always been pleased with the results. I’m currently looking for a product that will help keep brown water stains off my fiberglass hull right above the waterline. Most people in my area (Chesapeake) raise their bottom paint up to hide this stain, but I’d rather not do that. Do you think VS721 Bottom Coat might help? Waterline Stain Remover takes the stain right off, but Premium Boat Shine isn’t able to keep it off very long. VS721 Bottom Coat is a bit expensive to experiment with though.


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VS721 might work or it might not. It all depends on what the stain is caused by. If it’s caused by algae, it will seal the pores and protect the microscopic algae from getting in and causing the stain. If it’s caused by industrial pollution, tannin from decaying organic material in the water such a tree leaves or roots, or a metallic stain such as from iron or rust, then it will not prevent it and nothing else will either.

The advantage of using VS721 is that the stain will be on the VS721 and not the gelcoat, so it acts as a sacrificial barrier to help protect the integrity of the gelcoat. It’s easier to replace the VS721 than the gelcoat if it becomes permanently stained or damaged.

If you don’t know the cause of the stain then unfortunately experimenting is the only way to find out if it will work. If Premium Boat Shine does not work at all then VS721 will not either. If you are getting some protection with Premium Boat Shine, then VS721 will work better. VS721 is waterproof, Premium Boat Shine is only water resistant, and that’s why one can be used on the bottom while the other is limited to the hull above the waterline.

Wish I could give you a definite answer, but without knowing all of the parameters, I can’t.

Thanks for your question,

Captain Aurora
Richard Kittar

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