ventilation and de-humidifiers

[Rigger]

When laying up and using a de-humidifier do you tend to leave the boat ventilated or not? If you leave the ventilators open are you simply continuously drying outside air drawn into the boat? Is a dry sealed cabin better? I've always tended to leave ventilators open until someone pointed out the possible error of my ways.

 

[dnickj]

I always close the vents - once you have let the dehum do its job of drying the air you want to keep it in and also keep the damp air out

 

[shmoo]

Agree. Leave the vents open and you are (granted, slowly) dehumidifying the whole world. We close our hatches completely (i.e. not the slightly open but secure setting) and stuff newspaper in the dorade inlets.

We run the dehumid on about half setting.

 

[mikemonty]

Here's the thing.
the atmosphere has water in it.
Now, you can take a fair bit of the water vapour out in an enclosed space with a dehumidifier, but in doing so you have created a difference in the partial pressure of the water vapour in your boat compared to outside.
Unless you seal the boat up completely, more water vapour will FORCE its way into your boat until the humidity is the same as outside again (assuming the temperature inside and out are equal).
Use a dehumidifier if you have a mass of water soaking a large area such as fabrics and foam, seal the boat up from the atmosphere, remove the condensate as it forms, or else you are just going to recycle it, and the low relative humidity will cause the water in the fabric to evaporate out and thus dry out (again, if the area is ventilated the humidity will equalise from outside before much evaporates out of the liquid phase.)
Running a dehumidifier constantly is a waste of energy - literally - if the materials inside the boat are already no more humid/wet than the outside atmosphere.
Even without a dehumidifier, a well ventilated boat with no topside leaks should dry out nicely - except if the fabrics have been wetted with salt water. The salt is hygroscopic and will retain the water and consequently the damp feel.

Mike

 

[1317]

Day/Night Nicro ventilator made all the difference for me, positively.