Interior Condensation

[bindschadler]

Here in the cool, damp Pacific Northwest winter, we are experiencing an enormous amount of condensation inside our boat, particularly in the forward berth. When the sun shines (yes, it does occasionally), condensation forms on the underside of the deck fiberglass and on the berth ceiling and walls. Water drips down onto the mattress and runs down the walls an soaks the paneling (top and bottom). Both are stained causing its own problems, but first we need to stop the condensation.

We had been keeping the hatches closed tight and used a small heater to try and warm and dry the air, but I expect the boat can't be sealed tightly enough. Recently, I’ve covered all the windows (to prevent the sun from warming the interior air), opened all the hatches to the vent setting (to let warmer air out before the water condenses) and run two small fans (to keep the air moving so the same air doesn’t remain in contact with the colder surfaces and condense the moisture). Too early to report the results of the latest steps, but while I wait for the rain to stop and the sun to return, I was wondering what steps others take to minimize inside condensation.

Thanks for any ideas or comments,

[russp]

Hi Bob,

If the outside air is saturated then you have next to no chance to dry the boat out, and even a heater won't help get the water out of the boat as any air you push out is being replaced with saturated air and more moisture. I would be using a dehumidifier if you have power, or just dessicant packs if you don't, to pull the water out of the air (and the fabric, and the mattress, etc) and tip it outside the boat. While this is happening keep the boat as well sealed as possible to stop more damp air getting in.

Also make sure your bilge, shower base, etc, is also dry so you aren't adding to the moisture in the boat.

Putting some towels along the sides of the forward berth and catching any condensate while it is extreme, then drying the towels outside the boat, might hurry up the process. Sounds like you need to pull buckets full of water out of the internals!

Hope this helps.

Russ Peel
Avalon #150

[bindschadler]

Thanks Russ,
Venting the windows accepts defeat in trying to keep the moisture out of the inside air. I was hoping that by keeping the sun out (by blocking the windows) there would be little temperature difference between inside and outside air, thus minimizing any condensation.
Your suggestions are an alternative approach that attempts to remove all the internal moisture and limit/prevent more from getting in by sealing everything. I'm honestly not sure which holds the higher chance of success. I expect we'll try both.
Bob

[digitalvillager]

We use an Eva-Dry Petite 1100 dehumidifier (Eva-Dry.com). Its centrally positioned on the dry locker next to the galley sink. We gently drilled a hole low in the reservoir to keep it from automatically shutting off, installed a rubber grommet and inserted a plastic tube leading to the galley sink drain. Modifying the unit voids the warranty, but at $60 its a cheap solution. We have a friend that uses the larger 2200 unit on his C42, but the 1100 seems to work fine for us. Eva-Dry also makes a $250 desiccant unit if you don't want to leave the drain cock open. You can also use the humidity control feature on your Marine Air unit if you have A/C, but you run the risk of something getting sucked into the A/C inlet when you are not around. Our Eva-Dry unit has been running for the last 2+ years Mon-Fri (we "retire" every weekend to Quit In Time and use the A/C). Obviously, you have to be plugged in at the dock. You could install a second unit in the head if the humidity is REALLY high.

[R.B.]

We also use a dehumidifier, although our condensation does not seem as drastic as what you are experiencing. Ours does have a hose outlet, which runs into our galley sink. As long as the boat is sealed up, this works for us.