Cavitation; Ventilation - Mercury HP 500 EFI Bravo XR/XZ/III User Manual

CONDITIONS AFFECTING

Cavitation

Cavitation occurs when water flow cannot follow the contour of a
fast-moving underwater object, such as a gear housing or propeller.
Cavitation permits the propeller to speed up, but the boat speed to
reduce. Cavitation can seriously erode the surface of the gear
housing or propeller. Common causes of cavitation are:
•
Weeds or other debris snagged on propeller or gear housing.
•
Bent propeller blade or damaged gear housing skeg.
•
Raised burrs or sharp edges on propeller or gear housing.

Ventilation

Ventilation is caused by surface air or exhaust gases which are
introduced around the propeller resulting in propeller speedup and
a reduction in boat speed. Excessive ventilation is annoying and
usually caused by:
•
Drive unit trimmed out too far.
•
Damaged propeller or gear housing, which allows exhaust gases
to escape between propeller and gear housing.
•
Drive unit installed too high on transom.
500 EFI Bravo
OPERATION
69