by Timbre 19 » Sun Mar 08, 2015 7:41 pm
Hello,
as I mentioned "the Cold Wall Principle" is a (maybe bad) google-translation from swedish. But here comes an explanation, also that translated from swedish by Google!
Cold wall principle.
One way to achieve well-ventilated, dry and pleasant climate in the boat is to allow the incoming air to pass a "dehumidifying chamber" as follows:
The Cabin should be as dense as possible, with the exception of a few low-placed openings for air intake and two or three larger valves, type Electrolux, on the cabin top for outgoing air.
The air is preferably in through the ventilation hoses in the cockpit rim compartments. The hoses are led down below the waterline to spaces below the berths. Where the air hits the cold, bare hull and moistened by. The condensate is collected in the bilge and the dehumidified air is sucked into the cabin through the warmer air which rises and exits through the vents on the cabin roof.
It is usually called "cold wall principle 'has beneficial effect on the boat's interior climate in two different ways at different weather situations. "Cold wall" is part of the underwater hull, which has poor thermal insulation and therefore a temperature close to the surrounding water temperature.
In the first situation, preferably in the beginning of the season, pushing warm, moist air from the shore out to the boat close to land and in cold water. The moisture-laden air enters the ventilation system beginning where it hits the "cold wall" that has been cooled by the cold water. If the humid air has a dew temperature higher than the wall temperature condensing a portion of the air moisture to water on the wall.
The air thus has lost part of its moisture before it enters the cabin and it is favorable. One minor drawback is that condensation runs from the cold wall, inside of the hull, the bilge.
In the second situation the air temperature is low, for example a cold late summer night, but the water temperature is high. The cold air enters the ventilation system beginning where it hits the so-called "cold wall", but in this situation, the wall is heated the water to a temperature higher than the ambient air.
Air temperature is raised when the "hot wall" before entering into the rough and it is favorable. The ventilation system should start the air does not pass anything moist, such as wet ropes or wet bilges, because in that case humidified ventilation air, which is unfavorable.
Regards from Jörgen