Dehumidifiers on boats

[Don12480]

We live in the Pacific Northwest and it is obviously very damp throughout the winter months. One of our Yacht club members uses a dehumidifier which has a small hose that drains into the sink to keep the humidity down. This reduces the risk of mildew and he feels prevents the musty odours that can build up over the winter.
Any thoughts on this? Any dangers - fire? Can the humity be too low and dry the wood out?
I can't see any downside but thought I would put it out for general discussion.
Regards Don

 

[Stu Jackson]

That's a good idea if you're a liveaboard

but it requires you to leave the sink sea cock OPEN. If you're away form the boat...??? If it was my boat, I wouldn't. Have you asked him how he feels about this?

I've seen motor boats with this for air conditioning and dehumidification, and they have an above waterline thru hull discharge for the overboard water. You might want to consider that way to do it, and put a vented loop in the line with maybe a shut off valve to stop ingress when sailing. Would need a pump for the condensate either way it seems.

I'd also talk to more dock mates than just one and see what they do.

While we don't get the same amount of damp that you do, we'd used DryZAir for many years with success. Ventilation, as discussed here recently with another question is also important, but having 110% relative humidity air moving through the boat doesn't help much, which I guess is your point.

Another way to do it is to get to the boat much more often.

 

[Don12480]

I looked in the archives after I posted and found a wealth of information - next time I will look there 1st!

 

[Stu Jackson]

Good on you, Don. Amazing what one can find, ain't it?

 

[Benny]

We keep one, ours can be set for a desired % of humidity and we route the discharge hose to the bilge. It definitely controls mildew and musty odors. The only undesireable effect is that it produces hot air which in the winter is not a problem but in the summer it is.

 

[jibes138]

Potentials

Not sure it will help. I see two problems with this. 1.) If the boat is not sealed up pretty good from air flow then you will be essentially trying to dehumidify the whole world. So it will run continuously and cost money for electricity. This is because you will set up a potential difference and flows go from high potential to low. By drying out the inside of the hull water will try to flow so it may tend to make the fibergalss try to absorb moisture from the surrounding water versus if the hull is at equilibrium.
2.) I had a boat without dorades or other ventilation. It was horrible to deal with mildew. I now have a boat with two dorade vents and in 13 or 14 years I've never had a problem. I would invest my money in good ventilation to keep the air moving as opposed to setting up a potential difference.

 

[Franklin]

We have humidity problems down here too and some use a constant running Dehumidifier including me, and some just go with some kind of ventalation. I used to run two small ones from walmart for $50 each; one in the V-birth and one in the Aft cabin. Each took about a glass of water out of the air each day and kept the air moving which is also good. This winter I haven't been running either and haven't had much of a problem. Not sure if it's because the humidity level is down or I've just gotten better at keeping the boat dry. Maybe both.

To me, the only downside to having one is where to put it when you want to go sailing. I don't have room for a normal sized one that is really effective so that's why I went with two small ones.