Ventilation 101

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By: Capt. Frank Lanier

Nothing enhances the quality of life belowdecks during the heat of summer or when cruising hotter latitudes like plenty of cool, fresh air. Good ventilation provides a multitude of benefits, from prevention of odors, condensation and mold growth to the elimination of minor carbon monoxide buildup and its negative effects on crew health (such as headaches and seasickness).

Passive or Active

There are two types of ventilation systems: passive and active. Passive systems rely on the wind blowing over them to move air belowdecks. They either direct air inside or exhaust it (depending on their type and orientation to the wind). Examples of passive vents include traditional cowl vents, clam-shell or scoop vents, louvered hatch boards and low-profile discs (aka mushrooms). Passive vents work best when installed in opposing pairs, and while they can move a surprising amount of air on a breezy day, they don’t perform well on days with little or no wind.  –

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