Dehumidifier - will it make a difference?

[paulajayne]

A lot of dehumidifiers have an option to connect a pipe to drain the water - connect this and drain it into bilge.

Saves the hassle of having to empty it's tank.

[mikedefieslife]

Originally Posted by SVRocinante

Good day folks

Our first winter living aboard and the only real issue we're having is condensation! Warm, moist air hits the cold metal flanges of the portlights & hatches and we get rain!

I'm about to plunk down ~$200 on a Dehumidifier and wondering if it will actually make a difference. As I sit here writing this post it is 22 (degrees F) outside & 72 inside with 37% humidity.

If I'm understanding the relationship between Temperature, Relative Humidity & Dew Point correctly, I would have to get the humidity down to around 14% to stop the condensation at this moment.

Does anyone have personal experience with using a quality dehumidifier? Am I correct in my assumptions? If so, will one of the typical home units be able to do that?

Thanks for any and all help,

37% humidity? If that is case you don't need a dehumidifier. Your boat is already far too dry. Mould won't grow (it likes over 60%), but at that low a humidity viruses can thrive.

[SVRocinante]

Originally Posted by Smokeys Kitchen

...We had a small dehumidifier and it did almost nothing. We then got a larger one that we are very pleased with - removed a lot of water...

Thank you Smokeys Kitchen - I was looking at what looks to be a similar model; different branding

EcoSeb DD122EA-SIMPLE Desiccant Dehumidifier (Amazon link)

If I end up going this route, I'll report back tothe group as usual.

regards,

[SVRocinante]

Originally Posted by wrwakefield

Carlos and Maria,

The right dehumidifier will absolutely make a difference... [When used in conjunction with the right insulation, heat, and ventilation...]
.
.
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If you are interested in more details- including links to related information- see the page we maintain on this topic.

Thank you Bill; The blog post you mention above is actually how I got started down this path!
Thanks again for the great info!

regards,

[SVRocinante]

Originally Posted by Supers0nic

Put some bubble wrap over each port lite. It will help a lot while still allowing light in.

Interesting thought...

Thank you,

[SVRocinante]

Originally Posted by thinwater

If the relative humidity is 37%, all of this talk about dehumidifiers is off the point; you can't practically go much lower. The problem is insulation. You need to double glaze the windows and add boxes over the metal rims. This is the best solution. 15% RH will make your nose bleed and your woodwork crack... if you could get there, which I believe is impossible (most dehumidifiers cut out above 30%).

That's what I was afraid of and the reason for my post.
I keep the boat relatively dry - no water in the bilge, pump the shower sump dry, wipe down the shower after use, etc., etc. so we don't have a mold/mildew problem, just the darn condensation... some days worse than others.

BTW, for what it's worth, I purchased your book: Keeping a Cruising Boat for Peanuts a couple of weeks ago; great read!

Thanks again for your input,

[zeehag]

Originally Posted by Seabeau

Force 10 is out of business. However, Dickerson/Sig marine makes two vented propane models, one is the Cozy Cabin model which is an exact copy of the Force 10 unit. Sells for about $500. US. Note: Per Dickerson, their vented units must have at least two feet of exhaust pipe in order to vent properly.

it seems force 10 is building stoves and stove tops. i havenot found the heater, i believe it was discontinued. however the production of stoves and stovetops is continuing with force 10 being an eno company.
not out of business, just bought by others and discontrinued specific products.
FORCE 10 - Cooking Without Compromise

[guyrj33]

Compressor type dehumidifiers do add heat to a room. They pull in room air, cool it down to extract the moisture then warm the air back up before returning it to the room. The power they use to accomplish this ends up as heat in the space being dehumidified.
Perhaps the desiccant type produce more heat than a compressor based dehumidifier?

[Cadence]

Originally Posted by SVRocinante

Good day folks

Our first winter living aboard and the only real issue we're having is condensation! Warm, moist air hits the cold metal flanges of the portlights & hatches and we get rain!

I'm about to plunk down ~$200 on a Dehumidifier and wondering if it will actually make a difference. As I sit here writing this post it is 22 (degrees F) outside & 72 inside with 37% humidity.

If I'm understanding the relationship between Temperature, Relative Humidity & Dew Point correctly, I would have to get the humidity down to around 14% to stop the condensation at this moment.

Does anyone have personal experience with using a quality dehumidifier? Am I correct in my assumptions? If so, will one of the typical home units be able to do that?

Thanks for any and all help,

I'm not sure your problem isn't just the temp. differential to the frames. If you get down to 14% don't wear woolen clothing. Haier makes a good dehumidifier and will either supplement your heat or be your heater with the air it recirculates. Had you considered using a piece of ridged foam to make gaskets, for lack of a better term, to place over the frames as removable insulation during cold weather.

[Jansen2]

From experience I can tell it does.

Installed a dessificant type (after some reading): Meaco dd8l beginning of december. I do not live aboard and closed all (except cabin entrance) openings using plastic and tape. Around the cabin entrances there are still minor openings (couple of cm2). Boat is in Netherlands, on the dry. Not moveable much stuff inside anymore. Outside air temperature typically 3-10 degrees Centigrade. Outside humidity not measured but probably above 60 all the time.

At its highest setting the humidity dropped within a couple of days to 25% (varying 5 or thereabout).

I dehumidify to slow down rust.

[Locquatious]

Insulation is the best solution and sealing around the insulation is essential. Moisture will condense when the surface temperature goes below the dew point. When you insulate, the interior surfaces of the insulation are warm and approach the temperature of the interior air. If the relative humidity is below 100%, by definition the air temperature is above the dew point. If the air cannot get behind the insulation, because it was sealed around the edges, air cannot bring in moisture and water will not condense behind the insulation.

Another technique is to actually vent the warmest air out. That warm air holds the most moisture. By venting that air, the air at lower levels actually dries out.

Finally, one could circulate air in a looped pipe or plenum, from inside the boat, to the outside, and then back inside. This would remove moisture from the air. When the air hits the pipe or plenum surface that is exposed to the cold outside air, the moisture will condense. This moisture could be collected into a low point in the pipe, like a trap, and allowed to drip out. Finally the air could be heated, say with dry electric heat before it re-enters the boat.

This is essentially what a dehumidifier does. It passes air over a cool surface, condenses the moisture, and then reheats the air. But the dehumidifier uses an inefficient refrigeration cycle to form the cold surface. Although it returns some of that inefficiency as heat to reheat the air, there is a significant power wastage. It is better to make use of the existing outside cold air for the condensation step and then simply heat it with a dry heating source like electric heat or vented propane, wood, or diesel heat. Electric heat is nearly 100% efficient and you only need a small fan to circulate the air through the pipe.

[EmeraldCoastSailor]

I don't have a winter situation to deal with but my dehumidifier works wonders to make the boat more comfortable. When I sail I unplug it and lay it down in the head in the shower area out of the way. At the slip it sits on the counter and drains to galley sink. It comes out when I cruise so as to be able to use the shower portion of the head (and I don't have a generator so running it isn't in the cards unless I am in a slip).

With the unit running I have found I don't need to run the AC to keep the boat comfortable in the hottest most humid days on the panhandle. Come November the unit comes out till the heat/humidity returns in the spring. I bought it at Home Depot for less than $200.

The only drawback is the size but for me it works well.

[stormalong]

If you are not living aboard and not heating there is no need for a dehumidifier. The moisture comes from breathing, cooking and showering.

Having said that we have lived aboard and dehumidified with a compressor type dehumidifier. They work wonders on making life better aboard, Besides stopping the rain forest effect they prevent mold since mold needs damp to grow. You may need to prop open your lockers to get good air circulation. Most locker vents are minimal.

I am not familiar with the desiccant type and yes, the compressor type are noisy but they do add some heat to the boat. The noise can be reduced a bit by placing the dehumidifier on cardboard or carpet.

[thinwater]

Originally Posted by SVRocinante

... BTW, for what it's worth, I purchased your book: Keeping a Cruising Boat for Peanuts a couple of weeks ago; great read!

Thanks again for your input,

Glad it helped!

[seasick]

I have had great success with the relatively inexpensive Caframo, (West Marine) and Davis dehumidifiers by placing them directly beneath the dorade vents which are turned away from the prevailing wind (sucking mode). With smoke, I have observed the tornado that spins above these units and effectively moves the moist air out the vent.