# Condensation, it’s raining inside!



## SanDiegoChip (Jun 12, 2007)

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
Thanks,
Chip


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## SanDiegoChip (Jun 12, 2007)

*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).
Chip


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## StormBay (Sep 30, 2010)

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.


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## pdqaltair (Nov 14, 2008)

SanDiegoChip said:


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


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.


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## Capt Len (Oct 9, 2011)

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.


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## captflood (Jan 1, 2011)

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


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## PaulfromNWOnt (Aug 20, 2010)

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.


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## centaursailor (Nov 7, 2010)

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


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## ScuzzMonkey (Jun 26, 2006)

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!


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## amarinesurveyor (Feb 12, 2009)

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.
Brian


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## WDS123 (Apr 2, 2011)

Crack open a hatch where you sleep


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## SanDiegoChip (Jun 12, 2007)

*Soleus Air DP1-30-03*

We just purchased the Soleus Air DP1-30-03 30 Pint Room Dehumidifier. Our boat is getting very wet at night from running the electric heater. We have an electric mattress pad with duel controls that helps a lot. But the boat does get cold and damp. While here in San Diego we will use this to keep the boat dry. 
Let you know how this works out.










Chip


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## vega1860 (Dec 18, 2006)

*Experience*



SanDiegoChip said:


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












After three winters living aboard in the Pacific Northwest, I believe I can safely say that dehumidifiers and insulation will help but will not solve the problem. Ventilation and circulation of air and cooking and heating fuel that does not give off water vapor or at least minimizes it are the only permanent solutions to the condensation problem. Electric heat is best, propane is the worst.

If the boat is occupied, shoot for a complete exchange of air in the boat every hour or 15 CFM (Cubic Feet per Minute) per crew member (900 CF per hour) minimum. The typical 30 foot sailboat has about 1000 CF of volume IIRC. The more complete air exchange you can achieve the better. You will probably need to improve air flow (Cut holes in) lockers at least and probably install circulating fans to ensure dry storage spaces throughout the boat. Pay particular attention to the exhaust vents in your sleeping cabin and galley area and don't forget the lazarette.

A couple of four inch active exhaust vents with fans forward and a couple of passive vents aft may be enough but more will be better. Intake and exhaust vents should be as far apart as possible. An unoccupied boat may get away with one four inch solar exhaust vent forward and one passive vent of equal size aft.

OTOH, it is probably wiser to just sail to the tropics where you can simply open up everything and let the trades blow through


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## unomio (Jun 8, 2007)

If you are living aboard in San Diego we are extremely jealous of your condensation problems. The Pacific Northwest so far wins our award for creating "indoor rain" but Tonga is a close second. Our solution in the Northwest was a sizable dehumidifier, _after_ insulating with closed cell foam all areas next to the hull or deck not already insulated at the factory and installing an Espar forced air heater. In particular, the inside of the coaming (raised bulwark where the hull/deck joint is located) seemed to create rivers of water. At anchor in Tonga, with the relative humidity approaching 100%, we couldn't use a dehumidifier because it draws too much power and the air is 'way too hot anyway. We used a combination of Breeze Boosters, awnings, and open ports and hatches, plus cabin fans (especially in the V-berth peak). I recommend reading The Warm Dry Boat as a sort of primer for figuring out what your particular boat needs.


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## SanDiegoChip (Jun 12, 2007)

*Update*

We placed the unit in the head for now. It is a bit larger than we thought. We set the humidity level to 40. It is recommended for the room humidity to be between 30-50. We left it on over night and we used the heater. We got up as usual for work only this time the boat was dry!

Sometimes we up it to 60-70 as we like some moisture and the boat still stays dry.










We let this run at night to keep the boat from getting too wet. We use an electric heater with a thermastat to keep the boat from being too cold at night.
The boat still will get chilly but not real cold.










This hatch is over the bed. When this Sky Shade is closed it still stays mostly dry.










This one is in our head and is closed but stays dray any way.
Our port holes and windows stay dray and the boat never gets stuffy as the air moves about. 
On our 36' sail boat we alwasy have the fan on low when we have the unit runing. The fan has three settings. Unless we are cooking spaghetti or something with bowling water. 
For us it has been well worth it.
Chip


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## Brent Swain (Jan 16, 2012)

40 years of living aboard full time in BC has convinced me that the 1 1/2 inches of spray foam insulation is the only reasonable solution here. My boat is warm and dry, thanks to the insulation and the wood stove. If I turn my salt shaker upside down, it will completely empty itself . I have zero condensation problems. The ceramic bead insulating paint addative from High Tech sales in Florida, is a simple solution which may work in sunny San Diego. 
The more insulation the more comfort, period. 
TBTF as a paint addative for mold prevention is available in some paint stores. If it is not available in the US , you could get it in Mexico. 
I've heard a painting with a borax solution also works , tho I've never tried it.


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## SanDiegoChip (Jun 12, 2007)

Yes, doing something inside the lockers would be nice. We have been thinking of options. Spray foam seems the best way as gluing closed cell foam in there would be difficult.
We will be using AC in the future in Mexico so moisture is not going to be an issue but keeping out the heat will.
Chip


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## Maine Sail (Jan 6, 2003)

SanDiegoChip said:


> 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.
> 
> ...


Keep your bilge bone dry, that can help, but you give off moisture too. Electric heaters can't really "dry" the air but provide drier air than say many LPG etc. systems. If you have to compete with a bilge full of moisture and two adults you're going to get some condensation. Think air turnover....


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## Sea Diamond (Jan 2, 2012)

Insulation and vapor bariers aside, in a nutshell you need to start with 2 simple things.
1. Heat the interior warm enough so moisture will evaporate off the walls and "float around" in the air. The walls will appear dry but the moisture will still be in the air. Hopefully your heaters will have fans to move the air around, and hopefully they are safe. (I personally dislike electric heaters on a boat for safety reasons). 
2. Use a dehumidifier to capture that "floating moisture" - read the instructions that come with the DH as to what happens when the interior is not warm enough.

Then save up for a diesel hot air furnace.


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## SVAuspicious (Oct 31, 2006)

Ventilation is key. I concur with the earlier recommendation to get a copy of and read "The Warm Dry Boat" by Roger McAfee.

In the near term, take the doors off your lockers to increase ventilation of the lockers and even out the temperature differential.


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## pdqaltair (Nov 14, 2008)

*A nice, simple explaination.*



Sea Diamond said:


> Insulation and vapor bariers aside, in a nutshell you need to start with 2 simple things.
> 1. Heat the interior warm enough so moisture will evaporate off the walls and "float around" in the air. The walls will appear dry but the moisture will still be in the air. Hopefully your heaters will have fans to move the air around, and hopefully they are safe. (I personally dislike electric heaters on a boat for safety reasons).
> 2. Use a dehumidifier to capture that "floating moisture" - read the instructions that come with the DH as to what happens when the interior is not warm enough.
> 
> Then save up for a diesel hot air furnace.


I'll add to it:
3. Ventilation also "dries" the air if heat is in use; the colder exterior air is always drier because it is cold and cold air holds far less moisture. Houses generally ventilate through leakage; boats are much tighter and much smaller. The clothes drier and bathroom fans can also pull a lot of humid air out of a house.
4. Moisture comes from many sources, but the main source for live aboards is exhalation, perhaps 1/2 gallon per person per day. Add to that cooking, showers, and wet bilges.


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## Bronwyn (Nov 7, 2015)

PDQ! Tell us what you do!


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## pdqaltair (Nov 14, 2008)

Bronwyn said:


> PDQ! Tell us what you do!


Read the whole thread (post 4).
* Insulate + storm windows
* Minimize moisture. Add a shower fan or shower ashore. Dry towels outside.
* Heat the whole boat
* Dehumidify, if needed
* Dry bilges


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