Proper Interior Humidity

Jan 12, 2016
268
Hunter 410 Ladysmith, BC
This winter we put an eva-dry 1100 in our forward head. I drilled a hole in the tank, and used plumbing compression fittings and silicone to modify it to continuously drain into the sink. It's set on a timer and runs off and on throughout the day.

In our galley I have a 35 Pint Garrison dehumidifier set on auto at 50%, with the garden hose attachment used to drain into the galley sink.

These two devices above pull a lot of water out of the air. The big 35 pint dehumidifier is only on board during the winter. We bought it on a door crasher sale at Canadian Tire.

We have three low powered low heat/dehumidfier air moving devices plugged in and set on the floor for the forward, aft and main cabin. We leave the overhead vents for the dorades open to encourage air exchange.

All five electric items plugged in run off the shore power, and draw under 2 AC amps on our AC panel meter.

Additionally we live only 5 minutes from the harbour so once or twice a month we go down, check everything out, and I take a mini shop vac and remove every last drip of water from the bilge that the bilge pump can't manage to extract.

Finally we have a small open jar of tea tree power gel in our main cabin. It leaves a nice smell and is supposed to inhibit mould.

It has been one wet and miserable winter on Vancouver Island. We have no smells, and no mould in our boat.
 
Last edited:
Oct 22, 2014
20,992
CAL 35 Cruiser #21 moored EVERETT WA
I bought this one last year. It uses electricity, but has kept the boat free of mold and foul smell this winter.
Dehumidifyer.jpg
  • Remove 35 pints of moisture per 24 hours
  • Adjustable digital humidistat for precise humidity control
  • Will work in cold environments as low as 38�F
  • Bucket-full indicator
  • Easy roll casters for easy portability
  • Large digital LED and controls
  • Optional hose use for water elimination
  • Washable filter with filter monitor
  • 24-hour on/off timer
 
Mar 26, 2011
3,400
Corsair F-24 MK I Deale, MD
Interesting that no one actually answered the OP's question; what is the correct humidity range for wood preservation?

Museums specify 45-55% RH. Cabinetry people agree, and never greater than 70%. Several sites also caution against less than 20% causing cracking.

I have a dehumidifier and target 45-55%. It generally stays there, although it goes up when I cook or shower.
 
Sep 11, 2011
390
Hunter 41AC Bayfield WI, Lake Superior
It really depends on temp. Up north 50% in the the winter will fill your house with mold and fog your windows. 50% in the summer is fine. A hard number is impossible to state. The inexpensive dehumidifiers with a hose down the sink drain do seem to be an excellent affordable solution. A moldy boat is nearly as bad as a diesel soaked boat.
 
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