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With all the things to learn during your first year of cruising, boat mold might seem trivial, but let me tell you…I hadn’t a clue that I ‘signed up for’ cleaning all the walls and ceilings as a part of my cleaning routine. To help save you the ‘trial and error’ time of figuring out what works, this article shares the most efficient way we’ve found to battle boat mold.

Why Does Mold Thrive On Boats?

Bad air flow. One of the solutions to solving boat mold issues is to always have air flowing through the boat. Weather permitting, open up the hatches, portholes, and salon door. This, however, will invite in moisture in a tropical climate (see ‘moist air’ below), so regardless, you’ll have to tackle the problem from multiple directions. And those spaces in your boat where there isn’t any air circulation, hopefully there is a fan installed close by. Use it. It really helps.

Moist air. Condensation doesn’t only collect on the outside of your evening sundowner glass, it can also build on the inside of your boat. When cooler temps arrive, the warm air coming out of you finds the colder surfaces of your boat which, when you wake up in the morning, can make it appear as though you’ve just spritzed it with a spray bottle. It’s gross. You’ll also have rainy days where everything in the boat feels damp. Yuck! So the solution is to dry out the boat (see ‘bad air flow’ above)…and sail in warmer climates. lol!

You’ll Find Lots of Advice Online About Tackling Mold – Very Few Work

Don’t get me wrong. You’ll try it. It’ll look like it works, but it’s temporary. I’d spend hours wiping down all the ceilings and walls only to start seeing little black spots again a few weeks later. So frustrating!

I scoured the internet, looking for the least toxic ways to kill mold and tried them all. I had moderate success with an initial vinegar spray and wipe followed by a tea tree oil spray which we let air dry. The boat smelled great too! The problem though was we were cruising in a very humid environment with super cool nights, i.e. morning interior condensation – which deserves a post of it’s own, and with all the moisture, found little black spots again within a month. Grrrrr. 

The Best Way to Beat Boat Mold is Prevention

Even though we have yet to find a permanent solution to mold prevention, we’ve found a prevention routine that I can live with. Instead of weekly ceiling and wall wipe downs (yuck!), I do the following every other month:

  • To kill the mold – fill a spray bottle with 1/2 with vinegar and 1/2 with hydrogen peroxide. Spray liberally to ceilings and walls. Let sit for ~ 5 minutes. Wipe down.
  • For prevention – follow up with Concrobium Mold Control Spray. (Can also find it at your local hardware store.) If the space doesn’t have good air flow, use available fans to circulate the air to help dry. If you don’t have a fan in the room, Concrobium will eventually dry naturally, so no worries.

That’s it! Concrobium is odorless, colorless, and made of 3 different food grade inorganic salts. You can use it around your kids and pets and not worry about making toxicity concessions to help keep your sanity. On their website it states, “Because it contains no ammonia, bleach, acids or VOCs, Concrobium Mold Control is a great solution for marine enthusiasts looking to control mold without environmentally harmful chemicals.” Yes!!!

Wrapping up…

So really the solution is twofold and totally doable!

  1. Open up the boat when conditions allow & run fans when they’re not.
  2. Every other month, wipe down with vinegar/peroxide & follow up with Concrobium.

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