If they want to keep their pride and joy in as good a condition as possible, boat owners learn early on that there are certain nuisances that will keep coming back if they don’t stay ahead of them. One such pain in the stern is mildew.
Walk into a local chandlery and you’ll find a plethora of products, some of which claim to clean mildew stains, while others say they’ll kill mildew. We’ll look at some products developed to deal with mildew after it forms and ways to create an environment that will be less likely to help mildew grow.
Mold and mildew are the result fungi growing. Mildew forms on a surface like a shower stall, boat seat and other areas where moisture levels are higher. Mold includes many species of microscopic fungi that can thrive on any organic matter, including clothing, leather, and paper — as well as on cabin bulkheads and headliners in boats.
“Mildew is the result of not getting an area dried out,” said Mike Lightman, owner of Odor Removal Experts in Tustin, CA. “It’s not the mildew that prohibits you from drying out an area.”
Lightman said that mildew can create foul odors in areas from heads to cabins to engine compartments and lazarettes. “I get rid of 90 percent of the effectiveness 100 percent of the time,” he said. “Anything organic is subject to my control.”
Lightman owns a 40-foot Blackman sportfishing boat, and he uses a space heater in the bow to help keep the V-berth dry. That helps reduce the chance of mold forming.
“It only raises a few degrees and as the air circulates higher, if there’s an opening, the air exits,” he said. “If the air just sits, it’s going to condense and it will hang on the overhead and the moisture will sit on the headliner.”
One of the biggest contributors to problems on boats — including mold and mildew forming — is a lack of use. Using your boat and opening vents and hatches when underway to let air circulate through the vessel is one of the best ways to minimize mildew growth.
Many suppliers make boat and RV heaters including Xtreme Heaters, Caframo and Davis Instruments. The Davis Air-Dryr Marine Dehumidifier plugs into a 110/120-volt outlet. When it’s placed low in a cabin or engine compartment, it draws in cool, moist air via convection and warms it to above dew points. The unit has no switches or moving parts so operation is quiet.
Air-Dryr can be handled when it’s plugged in. A thermal cutoff switch shuts it down in case the air flow gets blocked. It’s built from polycarbonate so there’s no chance of rusting and the company says it can take an occasional hard knock.
Davis offers the Air-Dryr in two sizes. The 70-watt Air-Dryr 500 heating element handles up to 500 cubic feet and draws 0.6 amps. For larger boats, the Air-Dryr 1000 has a 130-watt element and takes care of up to 1,000 cubic feet of space. It draws 1.1 amps. Depending on the retailer, the Air-Dryr 500 costs around $50 to $55.
Cleaning Up the Mess
There are many products that claim to clean mildew stains; others claim to kill the fungi. Many have the same ingredients, but a company has to pay to get certified as a product that kills mildew.
The most effective mildew stain cleaners have one or some of the following ingredients: sodium hypochlorite, hydrogen peroxide and quaternary ammonium compounds. Of the three, hydrogen peroxide is considered “green” and can be used to clean a bilge and can be pumped overboard.
West Marine, Star-Brite, 303 and others make mildew cleaners. Check the ingredients to determine if precautions need to be taken when using them. Sodium hypochlorite is a bleach, which can’t be washed overboard into the water. Heavier-duty commercial products used by professionals include Steri-Fab and Envirox. The latter is hydrogen-peroxide based and comes in a gallon for use as a concentrated formula.
A relatively new group of products offered at Marine Detailing and Cleaning Supply comes from Xanigo Marine in St. Augustine, FL.
“The gist of dealing with mold and mildew is about removing it once it gets there,” said Xanigo Marine founder Robert Holmes. “It’s one of those areas in boating where taking a preventative approach makes sense. When we came into the market, there was no really good technology in the boating industry proven to stop it.”
While he wishes that boat manufacturers would apply Xanigo’s mildew preventer to the seats when a boat is built, Holmes said that most customers come to him with a boat covered in mold and mildew stains.
The process starts with using Xanigo’s sodium hypochlorite-based remover to get rid of the stains. The remover is an anti-microbial formula that kills the fungi so it won’t come back. In the second step, Xanigo’s Waterless Wash is applied to neutralize the sodium hypoclorite because it’s not needed after it kills the fungi. Once the mold has been killed, the third step is the Preventer. To keep the mold and mildew from returning, the preventer must be applied every 90 days.
Xanigo sells products and an application sprayer for professional detailers, and the kits for boatowners come with the products in a spray bottle.
Xanigo sells the trio of products as a kit for $99. You can also buy the preventer for $39.99 per quart. On a 25-foot boat, the quart will cover it 2.5 times.
Tips for Long-Term Storage
Now that we know how to remove the stains, let’s talk about prepping a boat before putting it away for a few months. The biggest concern for long-term storage is eliminating as much water intrusion as possible. Before putting a boat to bed for the winter, remove soft goods like bedding and mattresses and empty lockers and other storage areas. Whenever possible, leave interior locker hatches open.
Check seals around hatches and doors and replace them if they’re cracked or abraded in any way.
If you’re using a heavier-duty winter cover, make sure it has integrated vents. If a boat is shrink-wrapped, make sure ventilation ports are installed. Solar powered fans are a great tool to keep air moving. If possible, on a larger boat that’s stored on a trailer or stands and is accessible, use a plug-in dehumidifier.
Another way to lower humidity in a confined space is with chemical dehumidifiers that use calcium chloride to absorb moisture and then direct it to holding containers. They usually come in a tub or bag and can be place in lockers and other places where reducing humidity is difficult.
