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preventing condensation inside boat

Since it has become colder we have a problem with condensation in our 57 ft liveaboard. It seems to be mostly coming in under the windows and at various places under the gunnel(?)The bit where it goes wider about hip-height. The worst place is by the bed. Would putting more insulation in the wall help? The insulation at present is polystyrene.

Many thanks for any help.

Asked by: rachel welton  | 3.54pm, Tuesday 9 December

WW says:

The condensation could be coming from either the inside of the lining or possibly from inside the shell and running down from the superstructure.

In the first case, more insulation may help- though carpet, backed onto thin (3mm or 5mm) plywood (which has been coated with primer or varnish) can be screwed or even attached with Velcro to the offending area.

If the condensation is running from the shell, it is more difficult to work with, unless you can cut channels so it flows down to the bilge behind the linings- which may lead to other problems. It could be a leak of fittings, rather than just pure condensation. Windows, portholes, deck fittings (like vents and pump-out connections) can all let in water- which is more noticeable when its cold! Removing the lining might help answer that question, but is not the easiest thing to do.

Adding more insulation is quite difficult usually and time consuming. Increasing the ventilation of the boat, checking that drains in the windows are not blocked and carpeting the insides may be an easier option.

If you are using 230V mains, consider a dehumidifier. They work very well- using around 0.2kWh of electricity. It is quite amazing how much water they can suck out of the air! However they have to run for hours at a time, to get the best effect.

Mark Langley  | 9.43PM, Wednesday 17 December

Readers say:

Thanks very much, Mark ,for taking the time to answer. Your advice, plus some recent investigations beneath the surface, will probably much improve the situation,

Cheers, Rachel

rachel welton  | 5.20PM, Tuesday 23 December

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