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Ventilation systems

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.
  • 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.

exhaust-air-intake.jpg

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.

You, the owner of the boat, are responsible for keeping your boat's ventilation systems in operating condition. 

Make sure:

  • Openings are free of obstructions.
  • Ducts are not blocked or torn,
  • Blowers are operating properly.
  • Worn out parts are replaced with equivalent marine type equipment.

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:

WARNING

GASOLINE VAPORS CAN EXPLODE.
BEFORE STARTING ENGINE OPERATE 
BLOWER FOR 4 MINUTES AND CHECK ENGINE COMPARTMENT 
FOR GASOLINE VAPORS.