Overwintering without electricity. How to keep moisture/mildew down ?

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DistantDreamer

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Hi,
I keep the boat on a river mooring in Lymington during the season & then have been overwintering in a marina to use mains electricity to allow me to run a mains powered dehumidifier. Marina costs at least £1200 + electricity for a few winter months (similar for starage ashore). This a clearly a high price to pay for keeping the boat dry. I am considering leaving the boat on the river and trying other ways of keeping the moisture/mildew down. I wondered if anyone had any experience with chemical solutions for keeping the moisture levels down eg Buckets/bags of Calcium Chloride. If not chemicals what else without shore power ? I know ventilation makes difference but there are some security limits on what can be left open. The boat is 36 ft. Any advice gratefully received.
 
DistantDreamer said:
Hi,
I keep the boat on a river mooring in Lymington during the season & then have been overwintering in a marina to use mains electricity to allow me to run a mains powered dehumidifier. Marina costs at least £1200 + electricity for a few winter months (similar for starage ashore). This a clearly a high price to pay for keeping the boat dry. I am considering leaving the boat on the river and trying other ways of keeping the moisture/mildew down. I wondered if anyone had any experience with chemical solutions for keeping the moisture levels down eg Buckets/bags of Calcium Chloride. If not chemicals what else without shore power ? I know ventilation makes difference but there are some security limits on what can be left open. The boat is 36 ft. Any advice gratefully received.
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Hi. I mostly over-winter afloat with no mains hookup. I ensure i have no rainwater leaks, a dry bilge and a modest amount of ventilation (2 louvred vents in cabin doors only). I get no mildew and all cushions and beding remain on board.

Colin. Www.solocoastalsailing.co.uk
 
I usually spend the months of December, January and February in a marina berth with electricity. As much as anything to keep the boat dry by running a little electric heat. It's odd that you pay so much -- I pay much less than that for a 54', and in Cowes no less, and with leccy included.

The other months I do what Plum does -- good ventilation and everything dry inside. Ventilation is key, and I have six large dorades for this, which I aim strategically. I regularly run the Eberspacher. Once winter rates kick in on 1 November, I spend most weekends in a marina somewhere or another and run the electric heat to dry out the boat.
 
DistantDreamer said:
Hi,
I keep the boat on a river mooring in Lymington during the season & then have been overwintering in a marina to use mains electricity to allow me to run a mains powered dehumidifier. Marina costs at least £1200 + electricity for a few winter months (similar for starage ashore). This a clearly a high price to pay for keeping the boat dry. I am considering leaving the boat on the river and trying other ways of keeping the moisture/mildew down. I wondered if anyone had any experience with chemical solutions for keeping the moisture levels down eg Buckets/bags of Calcium Chloride. If not chemicals what else without shore power ? I know ventilation makes difference but there are some security limits on what can be left open. The boat is 36 ft. Any advice gratefully received.
Click to expand...

Welcome to the forum!

Solar powered ventilators? https://www.google.co.uk/search?q=V...oTCOnIopHEi8gCFQhUFAod4vYIAw&biw=1920&bih=948
 
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Any heat will work wonders, solar (Yes, even in winter, especially thermal as opposed to PV) and wind. Dump all its output into a fan inside. The air circulation will keep things sweet and the heat from the fan motor will keep the air dry.
 
I have used water absorbent granules in the past with some success, but that was in a smaller boat, a Sadler 29. For a larger boat I think ventilation ventilation ventilation is the way. I still use the granules in my cockpit locker where there are some electrics and the dehumidifier doesn't reach.
 
Adequate ventilation works. In around 40 years, I've never used a dehumidifier on the boat, and never brought the cushions home.
 
Many thanks for the great advice. My takeaways from this are:
1. Investigate ways of improving ventilation. I like the solar power fan idea & have been thinking of solar anyway to keep the batteries topped up on the mooring in the season. Is there still enough light in winter to run a fan ? 2. Lower cost marina at Cowes. I researched quite a few marinas in the area to check for lower prices (including Poole) but couldnt find any significantly cheaper (Yarmouth IOW was a bit cheaper). Could you please tell me which of the Marinas in Cowes gave you the good price. Was this their standard price or did you have to negotiate? 3. Chemical solutions. Still could do with further input on this one if anyone has the experience. Thanks again for you suggestions. Much appreciated.
 
Nothing beats a dehumidifier, but if not possible lots and lots of ventilation. I have used the chemical pots in virtually-sealed spaces, and they are better than nothing. So if no electricity I'd go for lots of ventilation plus the chemical pots in any shut lockers/bilge spaces. No point in using them in ventilated areas, you'd be trying to dry England.

As a broker I get on lots of different boats and in the winter the ones that are using dehumidifiers are much nicer: ventilation only in UK winters always leaves a subtly dampish feel.
 
Consider a cockpit tonneau cover. It circumvents locker/washboard leaks and heats up in any sun, promoting airflow. You can then also leave cockpit lockers slightly open which helps the flow of air even more.
 
We used the chemical dehumidifiers last winter - though only because electricity only stays on for a few hours at La Rochelle so could not run an electric dehumidifier. And being warmer not so challenging there

But did seem to be commonly used - and sold at all the local chandleries.

The setup we inherited with. The boat was small granule style moisture absorbers in many of the lockers, plus a couple of larger devices with holding tanks in the galley.
They did seem to absorb / extract a lot of water so seemed to do the job, but emptying the blue liquid in the holding tank ones had to be done carefully. Wouldn't want to spill the blue liquid

Will probably continue with the granule devices inside lockers - but going back to electric dehumidifier as primary tool
Sorry can't recall brands etc but mostly French sources - will be UK equivalents
 
How do you guys with dehumidifiers make your boats airtight? I have one but which works ok, collecting lots of water overnight, but then it was trying to dehumidify the West of Scotland.
I do have two solar powered fans built in to the coachroof but they do not work at night when the temperature is lower. What we do have here is lots of wind so it serves to keep the boat dry, my winter hatchboard is well louvred and there are a couple of dorades, two intake mushrooms forward and the deck hatches keep rain out when open a crack. All doors and lockers open where possible.
Good ventilation works well for me despite the winter cold and humidity.
 
pvb said:
Adequate ventilation works. In around 40 years, I've never used a dehumidifier on the boat, and never brought the cushions home.
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+1. The only issues I ever have are with wooden spoons, if I leave them aboard. Otherwise I have had no trace of mould or mildew in either my current or former boat. I have a Vetus dome ventilator in the forecabin, which I leave 1/2 open, and a louvre in the washboards. The boat stays ashore in winter, and if I spend a night aboard I make sure she is well ventilated and dried out before I leave.

My wee boat stays in an open-sided barn over the winter and can get a bit whiffy inside. Like the other she has a roof ventilator and louvres, and she stays bone dry on her mooring, so I think it's a lack of wind in the barn reducing the through draft. For her I use a crystal dehumidifier which works fine. One batch of the chemical lasts all winter. That's a very tiny cabin, mind you.
 
The key IMHO is avoiding water at source.
Particularly fresh water.
That means zero tolerance of rain leaks.

Secondly visit the boat often and clean it rigorously.
Bleach around the galley, get the bilge spotless, wash down any areas prone to condensation every few weeks.

Taking some cushions home makes space to have lockers open as well as keeping them fresh.
Take home any spare sails or other stuff that is cluttering lockers and preventing airflow or holding damp against surfaces.
Run up the engine (to full temp) that warmth will dry out the boat over time.

If you have a spare £1k or two, buy an eberbasto and go sailing every month.
 
Thanks again for the suggestions. I have a Eberspacher heater on board (it even works properly !). Now wondering if I could fit a remote control switch to come on for an hour a day or so. I checked their brochures and these are available. You can even switch them on/off with an SMS from the mobile ! Perhaps this combined with a solar fan to keep the air circulating all day. Not sure what the battery drain would be from the heater running. Would need to go down & recharge the battery every week or so I suppose. Thoughts ?
 
As others have said - boat on a river mooring all year round = plenty of air flow so ventilation is good. Clean everything and open all lockers if you're going to leave it for any period of time. I tend to go down once a month and open all the hatches/drink tea/look at the river for a bit and it's always fine inside.

Outside is covered with bird carp though...
 
My boat is laid up ashore for about 9 months of the year.I made a box to fit over the forehatch that allows it to be open without water ingress.The box is held down by wires and can be padlocked in place.I have a second washboard that has a large metal grill.So far over three years there has been minimal mould.
 
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