Winter Dehumidifier Strategy

[stranded]

We are having our first (ever) winter on the hard on the Vilaine in southern Brittany. The boat is reasonably well insulated with no exposed hull surfaces.

When we were in the Solent we didn’t use a dehumidifier and never had a problem. Last 5 years on the Dart we didn’t use a dehumidifier and had a few spots of mould on soft furnishings in a couple of them. In both locations I would visit for two or three days at least once a month over winter and would run the webasto diesel heater a lot.

In France in the boat park the appeal of an occasional visit is much reduced so plan this first winter to go out at 6 - 8 week intervals. We are not allowed to leave boat connected to power when absent, but I would like to use a Meaco DD8L as much as possible if there is any real point in doing so. That might involve:

leaving the dehumidifier on its minimum (30W) setting attached via a small inverter to the direct load output of the Victron Smart Solar attached to one of the 180W solar banks. Obvs this would give at best only intermittent dehumidifier operation at a very low level, and only then only more than once if the Meaco and the inverter will autonomously resume operation when reconnected to a useful power supply only when the sun is shining.

The other is to run the hell out of the dehumidifier when out there - maybe 5-7 days at a time to get things as dry as possible.

But is either of these actually worth doing. In the first scenario would the occasional low power solar option do anything useful at all, even if it would work?

And in case 2, would the humidity on the boat immediately return to ambient when we switch off the dehumidifier when we go home and negate any possible benefit?

Is there an option 3 I haven’t thought of?

 

[Ed Sned]

I was hoping there would be more of a response to this. I have considered exactly the same set up in the past, but I've never been brave enough to leave it connected and walk away. My fear is that with limited sunlight in winter, it would just flatten my batteries. I did install a low-voltage battery protector, but it was pre-set at a very low voltage and I didn't really want to risk putting my batteries through that.
Would be interested to hear if anyone else has made it work though.

 

[stranded]

Yeah, it’s the walking away is the worry. I suppose we could book into some accommodation when we’re out there for a week and not use boat power for anything else to see how it behaves, but it’s an expensive experiment if it isn’t worth it anyway - probably wouldn’t cost much less than just replacing the battery (460ah lifepo4) if the walk away suck it and see option went bad.

Perhaps we can take from the lack of response from the much smarter in these matters than me peeps on here that it’s such a daft idea it does merit a reply!

 

[Ed Sned]

I'm installing a heater over the next month, and so I suspect I will rely on going down periodically and giving it a blast, coupled with passive desiccant moisture traps...

 

[PeterBoater]

Desiccant dehumidifiers such as the Meaco do not like being switched off/losing power without being allowed to go through their shutdown cycle, leading to premature failure.

 

[stranded]

Thanks. And coolant ones catch fire. So I suppose that closes that road, which is perhaps for the best.

As I have no idea how south Brittany humidity compares to Solent/Dart, might be simplest just to vacuum pack as much as possible, then review and if necessary revisit next autumn.

 

[chris-s]

What about a bucket load or two of desiccant? Take a bucket, put a colander on the top and then fill it with one of those large bags of dessicant refills. That’s what we use to do when our previous boat was in a yard that had no power. Place them around the boat.

The other thing is air movement, get some 12v fans even some computer case style fans to keep the air moving.

 

[stranded]

Ah - we have Caframo Siroccos throughout the boat, each drawing 0.12A on low, so under 3A per day. Should be able to run some combination of those indefinitely through even a low sunshine winter.

Asked chat gpt re dessicant type/quantity. It thought it would be limited effect over extended periods untended - up to 2 months - in general areas so I’ll concentrate on black spots.

Thanks for your help.

 

[doug748]

I have never used a dehumidifier and rely on good ventilation, It may help if you are in a sunny part of the yard. I put desiccant trays in the smaller closed areas including the engine bay and a cockpit cover means you can arrange a really good airway in the main hatch area.

Also:

DSCF0064 by OldGoriot

One of these over the fore hatch means you can leave it cracked open. If I had power I would put a 25 watt bulb under the engine, maybe on a timer.

Good place to buy the moisture traps and crystals is Trago Mills
.