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ardoin 10-26-2008 08:51 PM

How do you keep condensation out of the bilge?
I open a floor board in the front and aft of the boat and let air circulate through. The problem with that is waking up at night and having to watch your step :rolleyes: . I've heard of folks using a 60 or 100 watt light bulb to keep the bilge warm. What do you do to cope with this live aboard, winter problem? Will the engine/bilge blower do any good?

billyruffn 10-29-2008 04:16 PM


West Marine sells a light bulb type of 'dehumidifier' but I don't know if it will handle heavy condensation. I think it's make for winter storage situations. The problem you have may be due the moisture from the living, breathing humans living aboard. With every breath you take you pump warm moist air into the boat -- it cools and sinks, contacts the cold hull / sole... et voila! A cabin heater might help. If you have shore power you could find an electric model, or if you're on a hook you might have to install a propane or diesel heater. If you go with a diesel/propane heater, make sure you buy and install properly a carbon monoxide sensor/alarm.
Also, seek professional advice on installation of a fuel based heater, fuel storage tank and supply lines. I have a friend that lost his boat in a fire that errupted during refueling of the diesel heater. He escaped unharmed, but the boat was a total loss.

ardoin 10-29-2008 09:51 PM

Thanks Billy,
I have heat onboard, both shore powered and diesel. Nice and warm in here, but below the water line gets moist if I don't vent the bilge a bit. Looking to see what others do rather than lifting a couple of floor boards.

J36ZT 10-30-2008 07:59 PM


My solution to condensation and lowering humidity levels has been a small pelter style dehumidifier. I did the research and concluded the ones around $25.00 were crap. The one I bought was about $65.00 and has been going strong for almost a year now. It measures 9"X6"X5" and uses 25 watts of AC power.

Even with showering aboard every day, the dehumidifier keeps humidity levels under control.

Skipper, J/36 "Zero Tolerance"

travler37 11-14-2008 04:20 PM

Now this was back in 1977,
Mounted two 4 inch fans.One pushing.One pulling.One fore.One aft.Did it for heat circulation but took care of the moisture under the floorboards to.Hate cold floors.Covered them with expanded metal that was coated with something thick and rubbery.No clue what that was.

Cant remember the brand i had but was something like this.

3" and 4" AC Axial Fans.

There are 12 volt around to.Just google 4 inch fans.

It worked for me:)

121Guy 11-15-2008 09:39 AM

J 36
Hi J36,

I'm evaluating one of these as well. Can you tell me where you place your unit, does it have a discharge hose or are you emptying it often and if it has a hose, where you run it to, does it work on 12V as well and last, the name of the unit and where you got it.

Thanks very much,

121 Guy

zaliasvejas 11-16-2008 08:04 PM

I keep two 75w bulbs on at night, but that just to keep the engine from freezing... The fiberglass sweats like crazy, and unless it is covered by insulation, any bare portion eventually will look like the inside of the freezer....
What really helped to keep the moisture out of the boat was the clear shrink wrap... You should see the amount of water I would find on the inside of it...
With the wrap in place, the coldest spot for water to condense is the plastic and not a liner above my bunk...
Never thought of using dehumidifier, seems like a futile effort on a boat...

xort 11-17-2008 07:35 AM

Are you talking of shrinkwrap over the top of the boat as a cover or something inside the boat?

I haven't done this but thought it would be worth considering: There is electric 'tape' used on the overhangs of house roofs to melt the ice dams. You could fish this under the floors to add heat under foot and keep these areas warm. They are wired for 110v. I suspect they are 10 to 15 amps draw.

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