"Eva-Dry" dehumidifiers


Advanced Beginner
Blogs Author
I'm constantly trying to keep humidity down in the boat, especially this time of year.

Current mode is a "flying saucer" passive/low-wattage dehumidifer in the v-berth, with a fan going to keep air circulating, plus a few "damp-rid" bags hung up in strategic places (head, etc).

The "flying saucer" I'm current using does not have a reservoir - it basically warms the air enough to create some convection drafts and keep condensation from happening. Which is cool in theory, but doesn't actually pull any moisture out of the air, it just keeps it suspended and moving around. Or something. It's.... "okay", but not great. Even with lockers left open, I find some places every springtime that ...uh... stayed damp long enough for stuff to get grungy.

Just got an ad from Fisheries about "Eva-Dry" dehumidifiers


... and wondered if anyone has used them and had feedback? The things that have my attention are that they have a reservoir, are rated based on how much water they actually pull out of the air, and will run on 12V or 120V at relatively low power...

Or, if anyone has any other super-duper dehumidifiying tips... let me know.


Frank Langer

1984 Ericson 30+, Nanaimo, BC
In our damp Pacific Northwest, and our boats not being very airtight, I wonder if a dehumidifier would have any real effect. Yes, it would draw moisture from the air, but wouldn't air leaks just add that level of moisture back in? Heating the boat would allow warmer air to absorb more moisture, rather than it condensing, so might keep the boat a bit drier, but air leaks might make this an expensive prospect if done all winter.
I'll be interested in what others think.


Member III
I use the Eva-Dry here in Houston and I'm on my second one in 3 years.....I think it works ok here in the winter time when the humidity inside our boat is high....The reservoir fills up about every 5-6 days.


Contributing Partner
From having a waterlogged boat that needed many thorough rinsings, I can state that they do work surperbly. I got the humidity down to 20%. There is a big problem though. Most all dehumidifiers will only operate in a relatively narrow temperature range that is close to the temps that you keep your house. The cost of keeping the temp up and running the refridgeration coil in the dehumidefier makes the cost unacceptable for most of us. I have found a dry bilge (shaft seal), an electric heater set on low, and one or two dri-z-airs keeps the humidity in a reasonable range. I keep two humidity monitors on board.

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
Another PNW sailor - living aboard means I'm constantly breathing and making moisture in here via wet clothes, tea kettle, etc. I use a large Meaco Zambezi DD8l dehumidifier that tucks in nicely in front of my mast. This generates some warmth and keeps the boat at a steady state 50% humidity (but would go lower if I wanted it to.) I empty the reservoir daily but it has a hose attachment I could run to the bilge if I so desired.

Excuse my mess...

I use those Eva Dry 333 plug-in rechargeables for my hanging locker and want to get another one or two to put in my under-settee storage areas, as I think those take some moisture from the bilge / hull. I have to recharge it maybe weekly or bi-weekly, which takes an overnight plug-in to the wall socket. This works for me as I'm here most days but obviously, once it's "full" it's not doing any more work for you and would require a boat visit.

Otherwise, I generally try to keep things away from walls/the hull, keep fresh air moving, and check the dark spaces occasionally to make sure nothing's growing.


Also worth noting that the Eva-Dry plug-in models are Peltier dehumidifiers, which operate by passing air in front of a cooled medium to collect moisture, which then drops into the reservoir. These can freeze and stop working if the ambient temperature drops to a certain level, which it can and will do around here.
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Curator of Broken Parts
Blogs Author
I'm a little unsure on this point: The installation instructions for the Webasto heat pump (which dehumidifies) says DO NOT run the condensate drain to the bilge - it wants its own through-hull. (I figured a Tee onto the lavatory drain would probably do...) But it seems to me that the rate at which the bilge (or say, the shower sump) gets pumped out is likely greater than the rate at which bilgewater would evaporate back into the air. But I have no experimental evidence.

(Until now, the flying saucer thingy has worked OK for me. The boat came with it plus a stack of desiccant traps. There was a family of three living on board prior to that.)


Contributing Partner
Hey-A family of three on a 29 live aboard would be a real challenge. Are they all still alive?

One problem with teeing the condensate line would be that you can't then close the thru hull off. You get both freezing water and freezing air where you are (a drawback of sitting in fresh water on a mighty river). I remember Loren mentioning that a boat in his marina sank during a thaw with the probable cause being the ice split the hose attached to the seacock. The result being a rush of water into the hull upon thawing. You could turn the Webasco off and close the thru hull every time it's going to freeze but that may not be acceptable due to human nature (oops! I forgot to go down to the boat and turn it off). If the condensate load is small enough, perhaps you could drain it into a separate sump or maybe you should ignore the instructions and drop it in the bilge anyway. A dollop of bleach periodically would take care of odor problems.


Curator of Broken Parts
Blogs Author
I can assure you that when the water is going to freeze, the seacocks are all closed. But they aren't the usual problem, since it's usually warm (or at least not freezing) inside the boat, and the water doesn't freeze to the depth of the through-hulls. (River ice floats mostly above the water line, even when it's several inches thick.) It's the above-water drains: scuppers, bilge pump, engine exhaust, and putative heat-pump discharge that can get plugged with ice. I for one, don't plan to be living aboard in those conditions!

Re: the family of three. It seems like a long story, most of which we can only guess at. But it appears to have been a dank and unhappy one.

Kenneth K

Sustaining Member
Blogs Author
Year-round on the hook with no AC, I keep 6 Dri-z-air pots spread around the boat all the time -- 5 in the cabin and one in the engine compartment. I buy the refill powder in 10lb jugs at McClendon's. I remove most or all of the cushions for the winter and try to never leave any damp items in the boat.

Once in awhile, I'll leave an oil lamp or two burning overnight to get a little heat in the interior. So far, no mold problems over the last 3 years.
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Member III
I'm on my fourth PNW winter with the Eva-Dry. I like it. Haven't actually measured the humidity, but the cabin feels dry and there are no musty smells all winter long. I don't use the built-in reservoir because it fills up in a day or two. Instead I use the drain feature, running a tube into the sink. Which is exactly what my boat might do (it happened to Bob Morrison!) but I'm living with it.

One thing I like about the ED is that it is on all the time, generating something like 100-200W of circulating heat. So it's a flying saucer on steroids. At 10 cents per kWh, of course.

The last couple of years, I have been concerned about water leaking in through and around my foredeck windlass. So, in the winter, I point a domestic electric heater/blower into the chain locker, and plug it into a timer. I run warm air into the locker for about 1-1/2 hours a day. I'm assuming that helps. I'm not sure that the above description is clear. If someone is interested, I could post a picture.