Dehumidifiers

R

rogerbum

New member
All,

As I'm working on adding ventilation to the tomcat, I've also been looking into dehumidifiers. I've seen a few basic types
1) the saucer like units (or similar) which appear to be simply small heater/air circulators but which don't really remove water.
2) stick like heaters with the same properties as (1).
3) true dehumidifiers that run the air over cold coils, condense the water into a container (or out a drain) and
4) Various chemical dehumidifiers (usually using calcium chloride) in which the water is absorbed into a salt that is then disposed of.

For long term use in a humid environment, the only kind that make much sense to me is (3). Hence, for this winter I've ordered an household dehumidifier that I will set on the counter of the boat and have it drain into the sink. Are there marine units that are available which could be installed on a wall or in ventilated cabinet that are not huge? All I've seen at fairly large units that are appropriate for a much larger boat than a tomcat OR some tiny thermocouple cooled units that according to the reviews I've read are fairly ineffective. Anyone have any recommendations?
 
Roger, I've never used one. For the wet PNW winters all I use is one of the flying-saucer looking devices made for air movement (West Marine) and an oil heater I bought from Home Depot for about $50. Leave everthing open(cabinets, head etc) and turn both on low. No mold at all. I think if the air is dry & moving and warm without anything wet, there shouldn't be much humidity to remove. I also leave the head window open a crack so there's some fresh air coming in to the cabin and cover the boat. Last year I used one of the dehumidifiers made w/ the salt crystals and it hardly melted away w/ very little water in the tray after three months.
 
localboy":3uxm24ho said:
Roger, I've never used one. For the wet PNW winters all I use is one of the flying-saucer looking devices made for air movement (West Marine) and an oil heater I bought from Home Depot for about $50. Leave everthing open(cabinets, head etc) and turn both on low. No mold at all. I think if the air is dry & moving and warm without anything wet, there shouldn't be much humidity to remove. I also leave the head window open a crack so there's some fresh air coming in to the cabin and cover the boat. Last year I used one of the dehumidifiers made w/ the salt crystals and it hardly melted away w/ very little water in the tray after three months.
Click to expand...
I've been leaving all the cabinets etc. open and a heater on but I still get condensation and a bit of mold in the compartments under the berth and to some extent in the berth. In particular, the compartments under the berth seem to really collect condensate. I've open them up now and have a small heater and fan in that space which I think will help. However, after crawling all over in those compartments to clean out mold/mildew this past spring, I decided I was going to go overkill and stick a dehumidifier in for this winter.

Also, over the summer when I'm moored at Neah Bay, the compartments below the berth gathered some mold. I had a couple of spare fishing rods down there that came out somewhat green after spending the summer below. This was with a heater on during the week when we were gone and with the lids off of the compartments during the week. I think I'll get that solved once I install my ventilation system for that space (parts on order - will probably take a couple of weeks to get everything I need and get around to it).

So given the Neah Bay experience, I'm thinking I'll be dragging this dehumidifier to and from the boat all next summer. It's about 10 x 10 x 22" and weighs 32lbs. For the winter or other long term storage, it will be fine. However, for the summer at Neah Bay, I'd either have to stow it below while we fish OR cart it back and forth to the truck each week. Hence, the desire to find something that can be installed more permanently and/or something that isn't as large and heavy.
 
Roger,

Two of these do the trick for us. But, that's in Sunny Sequim, where we get a third of the rain you get on the "Dark Side" and a tenth of Neah Bay! :wink:

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Agree that the best dehumidifier is the #3: I have two Mighty Dry units. These are marine quality--SS bronze, compressor motors far better (and smaller than the "Sears" type of units. I probably will sell one of mine.
 
Same here, put a small electric dehumidifier - the chemical ones have costic by products and if there was an accident it would be a bad deal. As well a small heater to keep the inside above freezing. Never had any issues.
 
When I lived in GA I used #3 in a motorhome and a travel trailer and it worked very well. I made a grid to fit over the sink, sat the dehumidifier on it and ran a small hose to sink to drain the condensate to the outside, and it worked perfectly.

Casey&Mary
In Middletown,MD ... But headed back to The Villages
 
I have been very happy with the Dri-eze type products. Just calicum chloride granules. No cords/electic elements. And has worked great. Just don't spill the collected liquid on any ferrous metal. I use the bigger pail size that I place on floor in front of cuddy. Also you can buy bulk granuals at most pool supply stores. No fuss no muss.
 
I vote for the large stand up dehum. with the reservoir.
Had one on our racing sailboat, which was not very watertight when it rained.
I would empty the reservoir once a week in the winters.
Make sure you get one rated for below 50 degrees. Or else it will Ice up if it gets around 50 degrees and below. Strangest thing, and annoying.
They looked exactly the same at the store but different temp. rating.
Don't remember the brand.
my 2cents
 
We use the sauser like #1's year round in the 27 and have had very good luck with them. Keeps the boat dry and a little warmer. My father has the #3 type and they do fill up very fast with water, but hey this is washington so thats to be expected. We altered them to drain in to the sinks other wise they are full in a day or two. But they dont keep the boat warn at all and even ice up on the intake face. I truley that beleive that in washigton you would be best served with one of each #1 and #3.

Susan even noticed that our bedding was dryer when we used the dryer/heater #1's.
 
What works best depends on where you live. We lived for many years in S. calif--and nothing worked very well, if there was adequate ventilation. In the PNW, just a heater works very well. Florida--you have to have a compressor driven unit to get the best effect.
 
I've ordered a residential true dehumidifier of type (3) above and it will be set up to drain into the sink. I keep an electric heater on at all times in the boat (with a thermostat). I'm just hoping to identify a dehumidifier of type 3 that's a bit lighter/smaller and designed for marine use. I've spent a little time looking into peltier type devices and there may be some that will do the job but I think I'd have to modify them to drain through the sink or a though hull above the water line.
 
Roger,

I am using the same as Roger (Dreamer). I have used one of them plus a West Marine heater that has thermostat control to come on at freeze temps. I put the flying saucer type on the floor, elevated about 4 inches on a couple of boat hooks, so there is plenty of room for air flow underneath. The freeze heater is set to come on at about 36 degrees and will stay on until about 42. The first one has a fan so it keeps air moving, and the second is an adjunct for below freezing temps. I take the V-birth pads out and stand them on edge, and leave the front center window open about an inch and latched.

This year I am adding a second flying saucer but up to now I have not had any mold, mildew or sour smelling. As you are aware, it takes both air movement and drying to prevent that.

Harvey
SleepyC :moon

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