Condensation

It is that time of year again when the boating forums are full of people asking questions on how to reduce condensation aboard their boats. The simple answer of course is to increase the ventilation flow through the boat which will greatly reduce and often eliminate condensation build up altogether and reduce the amount of water vapour produced on board.

Some boats seem to be more prone to condensation than others which can only be put down to construction methods and poor insulation installations. Boats with large windows often suffer streaming condensation as a result of warm water bearing air coming into contact with large cold surfaces; double glazing isn’t as yet common place on boats. We have spent years improving the construction of our houses to provide better insulating properties, yet boat builders seem to ignore the lessons which have already been learnt elsewhere.

We are quite lucky with Naughty-Cal in that her construction is a naturally insulating structure, the air gap between the two skins acting as a natural barrier to the colder air outside. That coupled with the small windows and hatches provide an effective force against condensation build up in the cabin. We do provide lots of ventilation throughout the boat whilst we are aboard with the windows open and the hatches cracked open to provide lots of air flow around the cabin even in the coldest of weather. This needn’t mean that the boat is cold though as the heating system compensates for the temperature difference keeping the cabin toasty warm even on the coldest of days. The cockpit area does suffer with some condensation during very cold, still mornings which is hardly surprising given the canvas and plastic construction, but a few hours with the diesel heating on soon dries things out again. If there has been a breeze during the night the air flow around the cockpit keeps the area nice and dry but as the cockpit is designed to get wet, condensation here doesn’t cause a problem like it would in the cabin area of the boat.

Reducing the amount of condensation you produce on board also helps to keep your boat dry during the winter months. Cooking, bathing and breathing are the biggest contributors to condensation build up. Breathing you can’t do much about but it is possible to cut down on cooking condensation. Putting lids on pans on the hob, only boiling the kettle when necessary, using a slow cooker, and only washing pots when you have to will all reduce the amounts of steam produced. Where possible using land based shower facilities will also reduce condensation amounts considerably onboard. We are now only using our boat shower when away from our home berth, using the marina facilities most of the time instead.

There are a few other ways in which you can help keep a dry boat, ensuring your bilges are dry will cut down on moisture aboard and is good housekeeping anyway. Stagnant bilge water will start to smell very quickly. If you have a really bad problem with condensation then a dehumidifier may help to reduce the moisture aboard and keep the cabin dry but this does rely on a reliable shore power source. We use desiccant filled bags to aid keeping our cabin dry as it is a reasonably small area and given the amount of times during a winter that they need to be taken home and dried out, then I would say that they are reasonably effective at keeping moisture at bay. They may not be suitable for all boats however due to the limited protection that they can offer to larger spaces.

Reducing condensation is something that all boat owners should take seriously as the moisture can be a breeding ground for moulds and other fungus’s which can cause health problems as well as widespread damage to fixtures and fittings if left unchecked. Good housekeeping and adequate ventilation should however banish the beasties and help keep your boat dry and condensation free.