What Is Ventilation As it Relates to Outboards?

Ventilation, as it relates to outboard motors, generally occurs when surface air or gases from a outboard engine's exhaust are pulled into the blades of a boat's propeller. This phenomenon can cause your boat's motor to perform poorly.

  1. Effects

    • When ventilation occurs, your outboard motor's propeller pushes more air. This causes the propeller to stop pushing water, as it does normally.

    Significance

    • Ventilation reduces the amount of resistance against the propeller's blades because the propeller is pushing less water. This causes the propeller's blades to spin much faster, pulling in debris and generating little to no forward thrust. Over time, the effects of ventilation can wear down the propeller and the outboard motor.

    Causes

    • The main causes of ventilation in outboard motors are the motor's location or damage to the propeller. If a motor is mounted too high or too far from the boat's hull, air and exhaust can be sucked into the propellers more easily. If the propeller's blades are damaged, it creates gaps in the water that make it easier for air to be sucked in and form air pockets.