> Checkout a device by the tradename "HUMIDEX" , essentially it is
> a vent that picks up air at the floor level and vents it outside, driven
> by a fan, controlled by a humidity switch. It retails for about about $200
> Canadian. A small fan mounted in some 4 or 5" duct would accomplish
> the same thing but without the humidity switch and cost around $20, just
> let it run full time or on a timer and save the $180. Note that this would
> only be effective as long as the humidity at floor level is higher then it
> is in the air replacing the vented air. definitly ok in the winter.

> Greg

Greg, I don't want to turn the subject of this BB away from strip built boats and toward "ventilation and humidity control" (I apologize in advance to the owners of this BB), but I want to dispell some well-intentioned misconceptions people sometimes have. I have been designing industrial air conditioning, ventilation, and dust collection systems for many years as a mechanical engineer.

What you describe is a ventilation system. It doesn't remove humidity from air, it just replaces the air in the basement with air from somewhere else. The air you exhaust has to be "made up" from outdoors. It could come from upstairs, but that air will also have to be replaced, and the only place left is outside. Air will take the path of least resistance, seeping in through cracks to the outside, so on hot humid days you will just be bringing in hot humid air. On nice dry days this may be an improvement over the air that you exhausted, but in the climates typical of Minnesota and much of central and eastern Canada you will still have a damp, musty basement much of the rest of the time. In the winter you will bring in cold, unheated air that your furnace must then heat. If you have very tight construction, chances are that little fan will just be whirring along moving very little air. Propeller-type fans don't have the ability to move air against much resistance, such as pulling air through little cracks, so they just respond by moving less air while spinning at about the same speed. You need to have some good size openings to the outdoors to let air in. The same ideas about make-up air apply if you have a dust collection system that exhausts outdoors. However, even though dust collector fans are not propeller fans and have much greater ability to move air against high resistance, you may see an improvment in such a dust collection system if you provide a source of makeup air. This only applies if your dust collection system exhausts outdoors.

If you have a damp, musty basement, you will need a dehumidifier. So for about $300 canadian you could get one to create a very nice environment in your basement. By the way, don't run your ventilation system while your dehumidifier is operating, because you will be bringing in lots of humid air, and the dehumidifier probably won't be able to keep up. If your basement is not damp and musty, then a ventilation system will be just fine. You don't need the expensive humidity controller in this case.

Hope this helps.

Paul Jacobson