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dehumidifier and portable electric heater

Could you recommend a suitable dehumidifier to leave on a boat over winter.I am also thinking of placing a portable heater on the boat with a thermostat to say keep at 4'c / above freezing. The boat is connected to shore mains, any suggestions.

Asked by: michael Hawkins  | 11.56am, Sunday 27 November


WW says:

Tubular heaters work well- are low-power heaters that can be bought with a frost thermostat, so they are not on permanently, but when the temperature drops. Avoid fan heaters and oil filled radiators as they are not usually designed to be permanently run and some units have caused a number of boat fires.
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Dehumidifiers work well when connected to run a few hours a day- and set up to drain into a sink rather than a tank.
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However, both tubular heaters (or any low-powered heating) and dehumidifiers will really be negated by good ventilation- which is essential to keep a boat in good condition. For them to work well you would need to effectively seal the boat- which is a very bad idea.
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Dehumidifiers work very well on a boat that is damp and needs drying out- however they use quite a bit of power and work best in temperatures around 15 degrees Celsius or higher- which isn't wintertime! Poor quality dehumidifiers have also a poor safety record...
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Provided you have drained most of the water from vulnerable devices (calorifiers, shower pumps, etc.) then providing good ventilation is much better for the boat, cheaper and less impact on the environment- and decidedly safer. Ensuring one or two windows (if drop back vent types) are open, all high and low level vents free of obstruction, locker doors open and mattresses/cushions raised from the bases (to allow good circulation of air) you will achieve much better protection of the interior than using heaters and dehumidifiers. I only ever use a heater/dehumidifier combination if I need to actively dry out a boat or during repairs- for winterisation, or even leaving the boat between weekends, good ventilation is key- which is also what commercial operators of hire fleets do. It only takes a few minutes to do and is far safer. However if you choose to use heaters and dehumififiers, use ones with thermostats, overheat protection and place them where they cannot do damage to surroundings- ideally mount permanently and ensure cabling is free of kinks... and ideally check the instructions before you buy them to see if they are suitable.

Mark Langley  | 5.58PM, Sunday 27 November


Readers say:

Good day, this has been most helpful and much appreciated as aim to use the boat over the Christmas period so will purchase a tubular heater for between periods.

michael Hawkins  | 10.18AM, Thursday 1 December

Totally agree with the advice from WW about draining down and providing ventilation. There are however some conditions where a mild wet winters day is followed by a cold night then damp air can be introduced into the boat and when the air reaches dew point at night condensation occurs.
To counteract this, trays filled with silica gel cat litter can be used to draw any moisture from the air, similar to the small bags in electronic equipment packaging.

Ken Read  | 8.46PM, Saturday 21 January

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