Question: how to stop mould problems on your boat?

Mould problems on your canal boat?

Mould problems on your canal boat? - Credit: Archant

How to stop mould and mildew appearing when boats are laid up

Q) You often mention keeping windows open during winter months when a boat is laid up. We have had occasion to visit our boat and found mould/mildew on upholstery. Will placing bowls of salt around the offending areas help to reduce this issue (whilst still leaving windows slightly open)? - FAVOURS

A) TONY REPLIES: Bowls of salt will only act as simple dehumidifiers and if you want to use a dehumidifier effectively you need to seal the boat so no outside air can get in. If you do not you will simply be trying to dehumidify the whole atmosphere. I know of few boat windows or doors that are 100% air tight and then you have the vents required by the BSS. The idea of leaving windows open is to try to minimise the change in air temperature because the hotter the air the more moisture it can hold so as it cools in the evening or against a cold surface some of the water it holds will condense out as water droplets. Putting bowls of salt or a simple dehumidifier device in enclosed spaces like cupboards can help prevent condensation inside the cupboard. Anything that helps increase the water vapour inside the cabin will make condensation worse so try to ensure the cabin bilge is totally dry. You may also find the water absorbed by the salt is evaporated during the day as the boat warms up. I don’t think anything will be 100% effective so the goal should be to minimise the condensation. I also wonder what the moulds are living on. Do you try to clean the upholstery and surfaces regularly. You could always take the movable upholstery home for the winter.