The best way to fight mildew onboard is to keep it from ever starting in the first place. Prevention is your best defense. When storing your boat or leaving it closed up for an extended time, a few simple steps will help prevent mildew.
Clean and dry everything. Use a diluted water-bleach mixture on surfaces not likely to be damaged by the bleach. Wipe down and dry the head, shower, sinks, and the galley counters. Do the same for the overhead and walls/bulkheads.
Leave open all drawers, doors, and lockers to promote circulation. If covering the boat with a tarp, create ventilation between the tarp and the hull by hanging a few fenders between them. Prop up mattresses and cushions, or just remove them along with life jackets and foul-weather gear—even fenders and lines. Anything paper—charts, books, paper towels, etc.—should be stowed in air-tight bags or removed.
Good air circulation and moisture control go a long way toward keeping mildew at bay. Keeping the relative humidity below 55 percent throughout the boat gives you a good chance of preventing mold growth. Relative humidity can be measured by a hygrometer, available at many marine and air-conditioner stores, as well as some mega-retailers or hardware stores.
At the dock, a home dehumidifier, a dehumidifying stick (like the Golden Rod, effectively a small heater), or even a light bulb positioned under a vent can help promote air circulation and moisture removal. Moisture-absorption packets like silica gel can also help. These porous granules absorb up to half their weight in moisture from the atmosphere and can be purchased inexpensively in bulk at hardware stores.
The AbsorBag by Buffers USA uses calcium chloride to absorb moisture. The company also sells a non-toxic desiccant bag, E-Sorb, that uses montmorillonite clay for absorption. Star brite makes similar products, like the No Damp dehumidifier. PS plans to test these and other moisture absorbers in the future.
For more tips and advice on controlling mold and mildew as well as Practical Sailor’s recommendations on the best products for cleaning mold, purchase and download Practical Sailor’s ebook, Essential Marine Cleaners.
To read even more about the cleaning and maintenance of all your boating surfaces, buy the entire three-part series for the price of two! Available for purchase and download is Practical Sailor’s ebook series, Marine Cleaners. This three volume set contains the ebooks Gelcoat Restoration & Maintenance, Essential Marine Cleaners, and Specialty Marine Cleaners.
