Dehumidifiers

[TortolaTim]

Starting our 4th summer down here in FL and was thinking of getting an electric dehumidifier for the hot and humid summer months. I've been using 4 of those small Damprid buckets and running fans/ ventilating, which works "okay", but the boat still starts to smell a bit in summer and I do get a little mildew on the ceiling. Not to mention, dumping and replacing the Damprid crystals almost weekly is getting old and expensive. The boat lives at the dock and there isn't much of a breeze there to ventilate. I'm aware of the controversial aspect of leaving a seacock open, but mine are well maintained and I have proper hose and clamps on all my thru-hulls, so I'm fairly comfortable with using the galley sink to drain the dehumidifier. Does anyone run a similar setup, and if so, what's your experience with the effectiveness of it, and what type of unit do you have? Additionally, the boat is always on shore power and I pay a flat rate, so no concerns of the cost of the electricity. Thoughts?

[Breakin Away]

I do the Damprid thing during off-season haulout (we have winter here), with a small solar panel outside the canvas cover powering a fan to circulate air past the refillable canisters. That works great in winter here (I usually go all winter without having to refill), but definitely not enough for where you are.

During the season I have a Marinco solar vent in our salon hatch that blows air out, and fresh air comes in through the cracks in the companionway hatches. Works great here (never had any mold), but probably still not enough for you in Florida. However, there are LOTS of reliability problems with Marinco's latest solar vents requiring me to make annual warranty claims.

On our prior boat (C250) I had a small Peltier dehumidifier that sat in the sink, just like you suggest. It consumed 72 watts and ran constantly, but it's very inefficient - it didn't remove much water for the amount of electricity it consumed (maybe a pint a week at most). It was good enough for my little 25 foot boat in Pennsylvania, but probably not enough capacity for you in Florida, or for a larger boat anywhere. The Peltier types are sold under various brand names, the most popular being Eva-Dry. I'm telling you this so you can avoid them, since I doubt it would have the capacity you need.

For your needs, you probably need a full-blown dehumidifier (which runs with coils and Freon, like a refrigerator), which will be larger/heavier and perhaps a little cumbersome to put on your galley counter. You'd get these at Home Depot, Best Buy, or other appliance store. They usually have built-in collection pans that hold a gallon or tow (can go about a week), with a punch-out that you can attach a hose to that could go into your bilge if you need more capacity. That is what I would recommend for summer. Probably would fit under your salon table with hose going to the bilge.

Finally, if you have or want to consider a full-blown 120v marine reverse-cycle air conditioner in your boat (might be nice for Florida), they usually have a "dehumidifier mode" which will do the job much more economically than running the AC full blast. You'd run AC while you're on the boat in the slip, but run dehumidifier mode when you're away from the boat. Might be worth considering in Florida. This would require you to leave a through-hull open for the intake water. Water usually exits above the waterline. My boat has one of these, and it makes a huge difference when we spend time in the slip. I don't need to run dehumidifier when we're away because the solar fan is enough for us up here.

[Noah]

I have used an Eva-Dry 2000 successfully in my boat in SoCal for years. Sits on the galley countertop with a hose draining into the sink. The units were highly recommended by Practical Sailor years ago. However, they eventually wear out (start making a vibrating noise) and I am on my second one over the past six years.  They cost about $80 ea. so feel I got my monies worth. When this one gives up I will perhaps try another brand as the Eva-Dry 2000 seems to have been superseded. We don't get as much humidity here in San Diego, so these small units work well for me.

[Ron Hill]

Tim : I have a dry bilge and long ago I added a solar vent to the Vberth (about half way between the mast and the Vberth hatch). I'm fortunate that I have a 1988 C34 that has 4 inch dorad vents - rather than the 3 inch for 1989s and subsequent C34s. I also leave the head hatch cracked as long as the dodger is up (hoping the mud dobbers won't find that opening!!)  I also leave the companionway hatch all the way aft which leaves a covered opening between it and the hatch boards.

We have some humid summers here in Virginia, but I've never had a mildew/mold problem!!

A few thoughts

[Nicholia]

For your needs, you probably need a full-blown dehumidifier (which runs with coils and Freon, like a refrigerator), which will be larger/heavier and perhaps a little cumbersome to put on your galley counter. You'd get these at Home Depot, Best Buy, or other appliance store. They usually have built-in collection pans that hold a gallon or tow (can go about a week), with a punch-out that you can attach a hose to that could go into your bilge if you need more capacity. That is what I would recommend for summer. Probably would fit under your salon table with hose going to the bilge.

This is what I do in Seattle.  I used to leave it on the counter with the sink thru hull open, but then realized that since my bilge is never dry, I may as well run it in there.  I lash it to the mast under the salon table which means I don't have to stash it at all when I go out sailing.  I'm liking this set up.

[Jim Hardesty]

I believe the best is ventilation.  If passive is not working try solar.  Had the little solar/battery vents on my previous boat and liked them.

I'm fairly comfortable with using the galley sink to drain the dehumidifier. Does anyone run a similar setup, and if so, what's your experience

I know of some racers that use small Homedepo type dehumidifiers after wet races.  As far as I know they work well to dry out the boat. Problem I see is that dehumidifiers produce quite a bit of heat.  Not a good thing on a closed up boat in Florida temperatures.  Personally, have no first hand experience with dehumidify on boat.  Shamrock is airconditioned.  Previous boats were well vented.  Surprising how much condensation is produced on a muggy day.
Jim