Boat Ventilation

Why Ventilate?
Many older boats came from the factory with only a passive ventilation system and many new boats don't come with ventilation of any kind. It is easy to upgrade to a proper, active ventilation system or add ventilation to any boat with various products. This illustration on the right shows how typical inflow and outflow of air would appear on a well-ventilated sailboat. Proper ventilation is not just important for the maintenance of your boat, it is necessary for the comfort of you and your crew. A good ventilation system will Reduce moisture and humidity below decks when the boat is left unattended. It will also reduce the chances of mold, mildew and musty air development caused by trapped moisture and humidity in the boat. Your electronics and fabrics last longer by maintaining a drier climate and reduce the likelihood of blisters caused by moist air saturation of the hull.

Types of Vents
Vents fall into two basic categories: passive or active. Passive ventilators, such as cowl vents, clamshell vents, louvers, grilles, ventilating sails, ports, hatches and the Nicro Day & Night Solar Vents simply provide an access path for air to enter or leave the interior of the boat. As long as either the boat or the air itself are moving, they work just fine. Of course on those hot, still days when the only things moving are the mosquitoes, they're not much help.

Active ventilators, such as Nicro's Solar Powervent, Day and Night Solar Vent, Mini Vents and 12 Volt Vents, all incorporate a fan to keep air moving even when the boat or breeze is still. Solar energy or ship's power is used to power the fan depending on the ventilator. These vents come with both intake and exhaust fan blades for flexibility in creating your ventilation system.

Designing An Appropriate Ventilation System
A properly designed ventilation system provides adequate air circulation throughout the boat without adversely impacting the operation of the vessel. Experts recommend that your ventilation system should provide at least one air change every hour. This means provisions must be made for both the intake of new air and the exhaust of old air. Set up your system to provide a "crossflow" of intake and exhaust ventilation wherever possible. If you only add one active ventilator, use it for exhaust.

A typical 30-footer has about 800cu.ft. of below decks interior volume. Unfortunately, this space is often broken up into distinct cabins or compartments that may restrict the free movement of air throughout the boat. Therefore, simply installing a pair of vents rated for 800cu.ft. per hour of airflow may not be adequate to get the total ventilating job done.

Each cabin and head should have some kind of ventilation, especially if the space can be closed off from the rest of the boat. Louvered doors, or vent grills in solid doors, help air circulate into lockers, forepeaks and other isolated areas of the boat.

During wet or rough weather, you'll need to be able to shut off or remove vents to prevent water from finding its way below. Racing boats may need to use vents which can be removed while the boat is in use in order to keep the decks free of possible snags.

In Conclusion
Try to ventilate with intake and exhaust vents for optimum circulation. Larger 4" vents are about twice as effective as the conventional 3" vents - if you have the room for them, we recommend their use. Ventilation is also important when at sea in lousy conditions. Ensure that you do not have a "fair weather" ventilation system that does not include water baffles, because under those conditions the hatches will be shut tightly.

 

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