Volvo Penta AD31 Owner's Manual page 40

A propeller must be in good condition to give you
maximum output from your engine. A damaged
propeller causes vibrations and reduced speed. In
bad cases it can even cause bearing damage. Even
minor damage to the propeller can easily lead to
cavitation (looks like corrosion damage). Repair
such damage and paint where necessary. And always
keep a spare propeller on board.
The mechanism of the folding propeller must be
greased with Volvo Penta water resistant grease.
Please see the detailed instructions in the manual
when removing and refitting propeller/s.
22
PROPELLER
Remove the propeller/s and grease the
propeller shaft/s with Volvo Penta
water resistant grease.
Refit the propeller/s. Remember to
grease the shaft/s first.