Winter dehumidifiers

[Yealm]

How important is a dehumidifier (SW UK, Contessa 32 with lots of cabin wood, standard ventilation)? Shore power supply’s a bit problematic.

Is it a must, nice to have, or really not necessary?

What percentage of boats use one?

Sorry, I’m sure this gets discussed every year!

Many thanks

 

[vyv_cox]

We have never used one, owned for 30 years, wintered 7 years in Netherlands, otherwise mostly Mediterranean. Boat has always been dry. Note that dehumidifiers have a reputation for catching fire.

 

[Momac]

I have used a dehumidifier over winter since early 2017 .
I previously used moisture traps but they just were not doing a good enough job,
It's a Meaco dd8L

 

[fredrussell]

... Note that dehumidifiers have a reputation for catching fire.

The ones with a slight risk of that are the compressor dehumidifiers. Desiccant ones like the Meaco above operate in a completely different way and pose no risk. Or at least, no more risk than any other piece of electrical equipment you might have on a boat.

 

[Yealm]

Yes I’ve always used the DD8L. So not sure what the likely consequences of going a Winter without it…

 

[WoodyP]

A dehumidifier has been the saviour of my wife saddle room. Pennies to run, saving thousands of pounds of value. We also run one in the unused sitting room that houses our books, photo collection etc. No deterioration of all our valuables, running 24/7 so I would recommend it.

 

[Sticky Fingers]

I’ve always used one. Uk boat in the water over winter. Desiccant type essential.

 

[Kwik Decision]

I've never had a dehumidifier, and our boat spends most of winter afloat on the south coast. I do visit and run the heater quite often. I've also fitted computer fans at the front of the forepeak, and back of the back cabin, where we used to get some mildew. These keep the air moving, and have more or less stopped the mildew.

 

[Cerebus]

Yes I’ve always used the DD8L. So not sure what the likely consequences of going a Winter without it…

How much water did you collect when you used the DD8L and over what time period?

 

[ashtead]

You don’t really know volumes as ours has a drain pipe which means water goes directly down a sink outlet- I suspect it varies depending on setting and vessel/size material etc. I suspect though a tank fills in a couple of days (but that’s just based on usage in a shed)

 

[Cerebus]

You don’t really know volumes as ours has a drain pipe which means water goes directly down a sink outlet- I suspect it varies depending on setting and vessel/size material etc. I suspect though a tank fills in a couple of days (but that’s just based on usage in a shed)

Good point.

Last one I used had a collection tank.

 

[toothless]

I find air movement and ventilation is pretty much just as good assuming you don't have leaks. A solar vent was a game changer. If you do have leaks then a dehumidifier will help -but really you should be fixing the leak?

 

[Cerebus]

Desiccant machines; the crystals absorb water…

then what?

Are they heated and the vapour condensed and collected in a tank or deposited via a tube to a drainage port?

They can’t be re- heated in situ, because water vapour would go into boat again?

I wonder if I will be told by a minority faction “Google is my friend”, use the internet and find out for yourself? Fair enough. I may then be told “ so I know it all because I did an internet search…”

I won’t mind or reply this time because I am learning to be like Bob from Captain Sensible’s great joke on the Gag thread.

I only ask to add to the discussion and elaborate upon it.

I don’t need a dehumidifier but am mildly interested.

 

[Momac]

Desiccant machines; the crystals absorb water…

then what?

 

[Momac]

How much water did you collect when you used the DD8L and over what time period?

That depends very much on the weather conditions and specifically the temperature range . Big temperature swings generally cause more condensation. Constant temperature no condensation,
Very cold weather the air is dry anyway.
Also obviously there will be more water if people are present,
In an unoccupied boat the tank on the dd8L can fill in a few days. Or in other circumstances it can collect very little water.
Sealing the air vents in the boat is very worthwhile for the benefit of reduced energy used.

 

[Cerebus]

A perfect answer as usual with superb evidence produced.

Very informative.

Very interesting too; they obviously heat the crystals to dry them and that hot wet air is condensed and collected into a container which when full turns the machine off.

Interesting engineering going on in there;
The hot air to dry the crystals is presumably separated from the moist warm air in the boat holding the water vapour that impinges upon the dry absorbing crystals.

I wouldn’t want to engineer that.

Grateful for the excellent answer.

 

[Cerebus]

Interesting costs (if correct).

 

[Momac]

I wouldn’t want to engineer that.

Nor would I .
I do know much bigger versions the size of shipping container and weighing in at several tonnes are used on industrial scale projects. My job was making sure they would not fall through the floor.

 

[Momac]

Interesting costs (if correct).

Once the set humidity has been achieved the machine cuts in only when required. I use the lowest power setting and the least demanding humidity setting and that's sufficient.
Based on previous years I expect it will be £90 or so in electricity over the winter.

 

[Cerebus]

Nor would I .
I do know much bigger versions the size of shipping container and weighing in at several tonnes are used on industrial scale projects. My job was making sure they would not fall through the floor.

That is quite an engineering job.