Ventilation / Exhaust Blower
All boats built after April 25, 1940, and which use gasoline for electrical generation, mechanical power or propulsion are required to be equipped with a ventilation system. The ventilation system may be either natural or powered. The ventilation system removes fuel vapors from the bilge by circulating air through the engine and fuel tank compartments.
A natural ventilation system consists of at least two ventilator ducts, fitted with cowls or their equivalent:
- A minimum of one exhaust duct installed so as to extend from the open atmosphere to the lower portion of the bilge; and
- A minimum of one intake duct installed so as to extend to a point at least midway to the bilge or at least below the level of the carburetor air intake.
A powered ventilation system consists of one or more exhaust blowers. Each intake duct for an exhaust blower should be in the lower one-third of the compartment and above the normal accumulation of bilge water.
NOTE: Boats built after July 31, 1980, that contain power exhaust blowers in gasoline engine compartments must have the following warning sticker near the instrument panel:
GASOLINE VAPORS CAN EXPLODE.
BEFORE STARTING ENGINE OPERATE
BLOWER FOR 4 MINUTES AND CHECK ENGINE COMPARTMENT
FOR GASOLINE VAPORS.