While living on a sailboat comes with plenty of immeasurable positives—serenity, sailing adventures, enjoyment of nature, creating memories with friends and family, etc.—it also involves tradeoffs and ongoing challenges too.
In particular, battling the effects of moisture and reducing condensation are probably two of the biggest, unavoidable challenges for boat owners.
We’ve learned (sometimes the hard way) how to improve our ways of handling condensation and we want to share those tips with you.
Photo by EVREN AYDIN on Unsplash
How does condensation happen anyway?
Well, heat needs a place to go, whether it’s from your body while sleeping, from cooking, showering, or because it’s colder outside than inside your boat.
That temperature difference can result in condensation and if it doesn’t have a place to go (and evaporate), then it can result in mildew or mold buildup in your boat (or RV or tiny home).
So how do you prevent that from happening?
Here are some practical tips for how to keep condensation at bay:
*Btw, our posts may contain occasional affiliate links. It just means we might receive a small kickback if you try out something linked from our posts, but there’s no added cost to you and we only share stuff we truly believe in. Thanks! 
1) Aire-Flow™ Moisture Barrier (including a discount)
A dehumidifier can only do so much and won’t necessarily keep mildew and condensation from those harder-to-reach areas, like beneath your berth mattress.
For those areas, we highly recommend Aire-Flow barrier! Basically, it’s a layer of woven polymer that allows air to circulate and prevents moisture buildup. Brilliant, right?
Close up of the woven polymer material.
We suggest placing the Aire-Flow barrier under your berth mattress and, if possible, also under and behind your settee cushions (we learned the hard way that moisture buildup can cause mildew in and on the cushions themselves). We used leftover pieces to line our storage lockers and anywhere that mold and mildew can potentially hide.
We’ve been using Aire-Flow barrier for over two years and feel it’s so well worth it! 😅
Initially, we were a teeeny skeptical and didn’t want to foot the cost (especially when we had so many other needed supplies as new boat owners), but now, we can’t recommend this stuff enough and no longer worry about those areas for dampness or mildew. 🙂
If you want to get Aire-Flow, head here to get our 5% discount!
2) Dehumidifier!
Our dehumidifier goddess (for the time being).
The previous owners of our boat included their old dehumidifier on board. At first, we wondered, Ah, do we really need a dehumidifier?
Thankfully, we’ve kept it and realized it’s a godsend! We’ve learned that on rainy or humid days (or if we’re cooking a lot, for instance), the dehumidifier will do its thing, keeping the boat and our stuff dry, sometimes collecting a few cups of water in a day!
Tip for dehumidifier maintenance: One thing to keep in mind with dehumidifiers is to make sure you clean the reservoir and filters on a regular basis. According to the Family Handman, “Humidifiers (especially reservoir-type central units and portable units) provide both a growth medium and a distribution system for mold and mildew.” While this advice refers only to humidifiers, we feel it’s a good solution for humidifiers and dehumidifers alike to “[c]lean and treat the reservoir often with an antimicrobial solution, available at most hardware stores.”
We’ve been happy with our dehumidifier so far, but this model (GE ADEL70LR) is apparently no longer manufactured, so to give you more in-depth coverage about other types of dehumidifiers, check out this thorough blog, “Best Humidifier Choice.”
Frigidaire 30-Pint Dehumidifier with Effortless Humidity Control
This Frigidaire model is highly reviewed on Amazon and is on the “Best Dehumidifier Choice” list. We recommend a 30-pint version for a 35′ boat (or smaller) as it will dry 450 square feet, which is plenty, and obviously takes up the least amount of space.
When shopping for a dehumidifier, make sure to consider:
- Will the boat be docked or cruising most of the time when you use it? If the former, you’ll have more options to choose from. If the later, then you’ll obviously want to consider how much power it draws and consider ways to keep air circulating by using 12-volt fans and wind scoops.
- Make sure you look at the overall size and weight of the dehumidifier since floor space and storage are high commodities on most sailboats. Where will you keep it when in use and where can you store it so it won’t be in your way?
- Does it hold enough volume appropriate for your size of boat and humidity levels? Ours can hold 70 pints and, on the most moisture-filled days, we’re very glad about this capacity, but it’s definitely possible that we could go to a smaller size as it’s a bit bulky.
- Can your boat (or whatever electrical system you’ll be using) cope with the load in a safe way? For instance, we can only run ours when we’re connected to shore power because the unit requires 120-volts and would demand too much load on our batteries/inverter.
- Does it include a humidistat feature? If you’re planning to leave it on when you’re not on the boat too, this feature is handy so the dehumidifier will stop running when the humidity drops below a certain threshold and an automatic restart feature (especially crucial in the event of a power outage). Keep in mind there’s always a risk, however small, with leaving any electrical device unattended.
- Does it have non-slip feet and a lower center of gravity, both of which are better for boats (or other types of homes) that they tend to move around, lessening the risk of the unit falling over? Though our dehumidifier is taller, we make sure to empty it out and set it down horizontally before sailing and sometimes we’ve lashed it to something sturdy. When not in use, we store ours under our salon table and, realistically, we use it at least few times a week during the winter though not very much during other seasons.
3) Ventilate!
Using your galley stove for cooking is great, but the steam that you create from frying, boiling, using a rice cooker, etc. adds moisture to the air and, hence, more moisture inside your boat.
Whenever possible (hopefully on days when the weather is glorious), ventilate by opening up nearby hatches and ports, turning on fans, or running the dehumidifier shortly afterward.
And keep the air circulating with effective 12-volt fans and wind scoops!
4) Eva-Dry Renewable Mini Dehumidifiers
Pretty ingenious products—they’re renewable (up to 10 years!), non-toxic, and don’t require batteries.
Eva-Dry Products
We bought the Eva-Dry E-333 model ($15-18/each) for one of our cubby spaces (apparently works in areas up to 333 cubic feet). So far, so good.
We leave it and when the silica gel crystals have absorbed their maximum moisture and turn a dark color (takes about a month or so), we know it’s time to re-charge.
Two things to keep in mind: for small spaces, make sure you have an outlet area wide enough so you can easily recharge the Eva-Dry model that you have. Also, you’ll need to remember to re-charge them periodically.
5) Use old-fashioned elbow grease and non-toxic cleaning supplies
On a boat, some condensation is, as they say, par for the course sometimes, so if you notice any signs of mildew, try this eco- and pet-friendly option:
- Vinegar and water (roughly 1:3 ratio): Not only affordable, but this all-purpose cleaner can help prevent or clean up mildew and vinegar kills about 80% of mold species. We keep one glass spray bottle of vinegar and water in the galley area and one in the head for easy access.
16 oz. glass spray bottle
6) Solar-powered vents
Solar-powered vents are low maintenance and help circulate air inside the boat. Increasing the ventilation always helps reduce the likelihood of mold and mildew, but solar-powered vents (like dorade vents) won’t be enough to keep your boat completely free of condensation.
7) Passive ventilation from dorade (or cowl) vents
SeaLux Round Stamped 316 Stainless Steel Cowl Vent
Maintaining air flow is important, so from what we’re learning, passive ventilation options like dorade vents can help because they allow you have to air circulation, even if the weather isn’t great and they also give warm air a means of escaping too. We purchased a slightly larger version of these cowl vents made by Sea Dog.
And whenever possible, we also like to leave cabinets slightly open to allow for extra air circulation!
If you have any questions, please drop us a line at [email protected]. We’d love to hear from you!