Mildew Prevention

Mildew Preventers That Really Work

Any boat moored in a slip with a bilge is destined to have moisture. Absorbing that moisture and keeping the air moving are critical control factors. The last line of defense is to keep the surfaces clean and coated with a preventative substance.

Practical Sailor has again done a great job looking at cheap alternatives to the expensive off the shelf potions. Below is a snippet from the Practical Sailor article.

The two homemade spray formulas we tested each cost about one penny per ounce. Like the other mildew preventers in our test, you use these as cleaners by simply spraying the product on, wiping any excess away, and leaving it on. Before applying to any fabric, test the spray on an inconspicuous sample spot.

Formula A

• 1 quart hot water
• 1 tablespoon baking soda (sodium bicarbonate)
• 2 tablespoons washing soda (sodium carbonate)
• 2 tablespoons trisodium phosphate (TSP)5

Much like Concrobium (which it is modeled after), our homemade Formula A removed the mildew from test carpet on board and kept it away, even though the area got wet again. It was also very effective in the moist-environment lab test.

Formula B

• 1 quart hot water
• 2 tablespoons baking soda
• 2 tablespoons Borax
• 1 tablespoon TSP

Formula B was the second-place performer in the liquid group. It was certainly the best value. It cleaned well, prevented mildew from returning to the carpet, and greatly slowed mildew infection in the moist-environment test in the lab.

We also tried treating with plain vinegar, which reportedly works on some hard surfaces, but testers found the smell a little too overpowering. A 10-percent solution of household bleach (3-percent sodium hypochlorite) was one of the best cleaners, but this has to be used with care. Bleach will bleed or degrade many fabrics, and can harm the marine environment. For complete results and more tips on keeping your boat mildew free, be sure to check out the full test report on mildew preventatives at www.practical-sailor.com. Non-subscribers, or those who'd rather save some time and support our testing program, can also dive into our complete two-volume report on mildew cleaning and prevention The Mildew-Free Boat, which will help you take care of mildew once and for all, with minimal effort.