Boat ashore, dehumidifier or heater?

[derekgillard]

Malgrat is now ashore and for sale so I need to ensure she keeps dry during the winter.

Previous years I have used a dehumidifier purchased at low cost from B&Q and drained it out via the sink and that kept the boat dry problem is I worry about them causing fires.

If you don't use a dehumidifier do some of you use a Heater to keep the temperature up and moisture down and if so does it work satisfactory, I have an oil heather with thermostat I could connect to a timer.

Delbuoy

 

[PhillM]

I use a combination of both. Dimplex 500 frost heater and dehumidifier with both on a timer. I cannot drain out via the sink, so I go down weekly and empty the water container.

 

[Bobc]

Both

Warm air can hold more moisture, which the dehumidifier can then remove.

 

[nigelmercier]

My dehumidifier chucks out warmed air, so is ideal for such purposes. Not ideal for the Canary Islands though, so it's coming home to my shed.

 

[pvb]

Adequate ventilation is the key - you don't need a heater or a dehumidifier then.

 

[BlackPig]

Last year I built a "can solar heater" for the boat (you get plans from youtube) worked a treat. It costs nothing to run and no risk of fire. And ventilation.

 

[jwilson]

Adequate ventilation is the key - you don't need a heater or a dehumidifier then.

On a boat where the interior does not get much salt water introduced (no leaks/sprayhood/not sailed hard/no wet spinnakers brought below to repack) good ventilation alone CAN work, but more often than not it doesn't. On the boats where it does work, you usually find meticulous owners with overall covers on deck and through flow ventilation left open under these covers.

I get on lots of different boats in the winter and the most of the ones that feel nice and dry have dehumidifiers on board. The ones that are just vented almost always feel subtly damp, and if you go looking you find areas of mildew. Keeping the boat dry has long-term benefits, it dramatically reduces the long term formation of "black mould streaks under varnish" on bulkheads and panels, and probably (though I can't prove this) helps reduce the chance of hull "osmosis" as water molecules in the inner GRP skin can evaporate out.

Personally I run a tube heater 24/7 plus a Meaco dessicant dehumidifier on a high (very dry) setting for a couple of days, then a low setting for the rest of the winter. It turns itself on and off as required.

 

[Elessar]

Adequate ventilation is the key - you don't need a heater or a dehumidifier then.

You do if you want to keep the beds made and your clothes in the lockers. Or for the OP if showing someone round a boat that feels nice.

To th OP good item in PBO this month about the different types of dehumidifier, seems with the desiccant type you don't need a heater as well.

 

[pvb]

You do if you want to keep the beds made and your clothes in the lockers. Or for the OP if showing someone round a boat that feels nice.

To th OP good item in PBO this month about the different types of dehumidifier, seems with the desiccant type you don't need a heater as well.

Perhaps it depends on the boat. I've never used a dehumidifier. As for different types of dehumidifier, they all emit heat to some degree.

 

[vyv_cox]

I read very recently that the main cause of fires in dehumidifiers is that the air path filter becomes blocked with dust. I have also read that running one too vigorously on low humidity settings can cause problems to timber. Other than that they seem like a reasonable idea provided the yard is happy to leave power cables attached.

We run one for most of the year at home to cope with the constant damp problems of a house getting on for 200 years old. We run it twice per day for an hour each, which seems very effective.

 

[pvb]

I read very recently that the main cause of fires in dehumidifiers is that the air path filter becomes blocked with dust.

Dust blockage is very likely in a domestic environment, but much less likely to happen on a boat, thankfully.

 

[KellysEye]

>Both Warm air can hold more moisture, which the dehumidifier can then remove.

Agree.

 

[vyv_cox]

Dust blockage is very likely in a domestic environment, but much less likely to happen on a boat, thankfully.

Seems it becomes blocked by something because I read that dehumidifier fires on boats are not uncommon.

 

[lw395]

Seems it becomes blocked by something because I read that dehumidifier fires on boats are not uncommon.

I would think 2/3 of yachts in marinas have dehumidifiers?
How many have caught fire? About one a year?

That does not make it acceptable of course.
I suspect a few cheap dodgy units have caused the problems.
People's fridges and freezers at home don't tend to ignite, although there was a spate with one brand?

 

[vyv_cox]

I would think 2/3 of yachts in marinas have dehumidifiers?
How many have caught fire? About one a year?

That does not make it acceptable of course.
I suspect a few cheap dodgy units have caused the problems.
People's fridges and freezers at home don't tend to ignite, although there was a spate with one brand?

I can't quote any figures but it seems more than one per year get reported in the mags.

 

[pvb]

I can't quote any figures but it seems more than one per year get reported in the mags.

A quick Google doesn't find many mentions of boat fires due to dehumidifiers. However, one Yachting Monthly feature from 2011 on a Moody 54 which was destroyed says "But some insurance companies insist that a dehumidifier has to be rated as suitable for marine use, otherwise the policy is invalidated." Not sure whether this is in many marine insurance policies, but people who use dehumidifiers perhaps should check their insurance. It also begs the question as to how many dehumidifiers are "rated as suitable for marine use"!


http://www.yachtingmonthly.com/news/512811/dehumidifier-advice-after-fire-on-laid-up-yacht

 

[theoldsalt]

Adequate ventilation is the key - you don't need a heater or a dehumidifier then.

I totally agree. Quite unnecessary ashore and I use the boat's normal ventillation for the winter - no different to the summer and all my boats have remained dry.

I also agree that salt deposits inside the boat can affect humidity. So if necessary, wash the inside with fresh water before laying-up ashore.

In addition I never leave mains connected anyway when the boat is unused. This reduces the fire risk.

 

[pvb]

I totally agree. Quite unnecessary ashore and I use the boat's normal ventillation for the winter - no different to the summer and all my boats have remained dry.

I also agree that salt deposits inside the boat can affect humidity. So if necessary, wash the inside with fresh water before laying-up ashore.

In addition I never leave mains connected anyway when the boat is unused. This reduces the fire risk.

Seems we're outnumbered by those who automatically assume that a dehumidifier is necessary.

 

[Elessar]

Seems we're outnumbered by those who automatically assume that a dehumidifier is necessary.

Seems some people like to waste a perfectly good boat by laying it up! Ventilation stops mold but it doesn't make the boat feel nice if you actually want to use it.

Without a dehumidifier and heater, my quilt feels all cold when i get into it.
And I like to leave the quilt made up, clothes in the wardrobe and the boat ready for use.

 

[pvb]

Seems some people like to waste a perfectly good boat by laying it up! Ventilation stops mold but it doesn't make the boat feel nice if you actually want to use it.

Without a dehumidifier and heater, my quilt feels all cold when i get into it.
And I like to leave the quilt made up, clothes in the wardrobe and the boat ready for use.

Me too! I've never had a boat out of the water in the winter. And I like to use it occasionally in the winter too.