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SanDiegoChip 11-03-2011 04:39 PM

Condensation, itís raining inside!
What do others do about this issue?
This is our first winter aboard our 36’ sail boat. We have an Islander Freeport B plan. That means our stateroom is forward of the salon with a pullman queen birth to port. The head is forward where the V birth would be.
We use an electric heater with a thermostat which sits across from the bed between two hanging lockers. We also have an electric matress pad that heats up from the feet up keeping cooler at the top by your head. Two controls which is nice, wife and I have different tempetures. So far all is well.

The head door we leave open.
The salon door we leave closed.
The stateroom and head get some condensation. The head gets more as there are more cabinets that get the condensation. The cabinets are under the side decks. It gets bad enough in the cabinets it drips.
We have tried closing the head door and opening a hatch in the head to create the same temperature as the outside. No help as it still gets condensation. Also it is a cold trip to the toilet :)
We are going to try another heater in the head this weekend.
Would a dehumidifier work?
What works??
Insulating the cabinets with closed cell foam may work but that is not a quick fix, oh yea we are looking for a quick fix :)
Never mind the red box it was for another issue, it is where the heater goes though

SanDiegoChip 11-03-2011 05:31 PM

Read other posts
Looks like from reading other posts (should have done that first I guess) that a dehumidifier or insulating is the only solution(s).

StormBay 11-03-2011 05:54 PM

You may want to try Damp-Rid (they even sell packets that hang on their own hangers just for closets). You can pick it up at home depot or walmart. So far it has worked for us, remedying the same issues that you are having.

pdqaltair 11-03-2011 06:34 PM


Originally Posted by SanDiegoChip (Post 793465)
Looks like from reading other posts (should have done that first I guess) that a dehumidifier or insulating is the only solution(s).

In a nut shell, you need to get the indoor dew point (humidity--the temperature when dew starts) above the coolest outside wall temp. There are several ways:
* Insulate to increase the wall temp, but be careful; if the air circulates behind the insulation, water will will condense and you will have mold. Insulating a boat is a tricky business.
* Limit humidity generating activities. Cook with tight lids. Shower ashore.
* Dry the air with a dehumidifier. Search the threads; I have seen some very small ones listed.
* Skip the Damp-rid buckets. Each can absorb a few pounds of moisture, and you can exhale that in a night. They are ONLY for sealed boats (no vents). Waste of money in this case.
* Heat, but with a window (better, some other vent) cracked a bit. The cracked window needs to be in a heated space. The air out side the boat is certainly drier in absolute humidity (pounds water per cubic feet) than inside. It is a misconception that a heater can "dry" the air; raising the temperature of air lowers the relative humidity. However, since the wall temperature is still warmer than outside, it helps. It is people that put the damp in the boat, not the outside air.
* Run a fan on low. Air movement increases the temperature near the wall and thus reduces condensation.
* If windows drip, storm windows will fix that. Exterior covers help too.
Sail Delmarva: A Few More PDQ Upgrades
Sail Delmarva: Salon Window Covers
* Heat the whole boat, not just what you use; the cold rooms are going to see the same humidity as the heated rooms, but cold air can't hold the water.

Like a house, it's a little of everything. I've taken steps and don't get condensation, even in freezing rain. Nice dry air in the cabin. When I bought the boat, there were some drips, one being a hatch right over the pillows; one drop of ice water every 10 minutes.

Capt Len 11-08-2011 10:50 PM

If you can put up with the fan noise house type floor model dehumidifiers work well. about150 bucks. they put out considerable heat too.Pull about 2 or 3 liters a day Costco has a good one. Ps. I only use it at the cottage, boat's got a wood stove.

captflood 11-09-2011 06:20 AM

GREETINGS EARTHLINGS; Dry the bildges and get shut of all unessasary standing water and close off the toilet it will help to stop evaperationg water from recondencing on the colder sufaces STAY WARN DRY WELL FEDD AND DON'T BUMP INTO ANYTHING, GO SAFE

PaulfromNWOnt 11-09-2011 07:35 AM

Leave the salon door open, and heat the whole boat. You are limiting the ventilation options by keeping the door closed, and also reducing the volume of air that can absorb the moisture that you exhale.

Many little things are likely to be the answer, so experiment a little.

centaursailor 11-09-2011 06:11 PM

I,m trying warm touch paint additive in the cabin. I stripped out the old rotten lineing a couple of years ago and have had serious winter condensation since.
So far theres a noticable improvement in condensation were the paint is applied compared to the unpainted forward berth, just had our first frosts last week.
The thickness of the mixture is improveing the rough finish of the original fiberglass under the covering.
Early days yet but I reckon its worth aplying a couple of more coats as I still have half the additive left.
I dont live aboard so its not critical. Fitting a solar fan next year but want to see how the paint does this winter on its own.
Safe sailing

ScuzzMonkey 11-11-2011 08:06 AM

We don't have a hundred percent solution, but ventilation combined with heating certainly helps a lot. We keep vents cracked a bit even when it's quite cold out, and a fan type heater running. If we're doing something that generates excess moisture (cooking something steamy, or showering) we try to isolate that so most of the moisture goes out a vent instead of swirling about the cabin.

Our boat came with some insulation but we feel it wasn't well-done and generally does more harm than good; it just traps the water, whereas the areas of bare hull dry quickly and easily with a little circulation. We installed vents in many lockers and cabinets that did not have them previously, and that helps enormously.

Good luck!

amarinesurveyor 11-11-2011 08:58 AM

What kind of electric heater are you using? I suspect it is a radiant heater? I lived aboard my old Ericson 30 for a few winters in Washington DC and Annapolis and noticed that my friends that used radiant heaters all had a problem with condensation. I used two forced air heaters that blew hot air and circulated it around the boat. Both were on the floor, one aft below the companionway ladder blowing forward, and one as far forward below the v berth blowing aft. The warm air circulating through the boat dries the air (humidity goes down as the air temp goes up), and helps to keep the condensation from forming on the interior surfaces. I also put aluminum foil over the port holes to act as a strom window for insulation, which stopped condensation from forming on the glass. This setup worked in temperatures well below freezing and with snow on the deck at times. Hope it helps with your problem.

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