prop cavitaion issue -- need help

[nightowle]

Today the prop consistently cavitated as I accelerated my boat just beyond 4.90 knots. I have a 1975 O'Day with an Atomic 4 engine. I do not have a tach set up to the engine yet, so I won't be able to tell you exact rpm's this is happening at. But I normally can do upwards of 6 knots. The boat had been recently hauled in May and the prop looked fine and has been performing very well since leaving in June for an extended cruise in the Gulf Islands of BC. New zincs were installed in May, as well. We dove the boat back at the dock today, and noticed no changes other than some minor algae (which we cleaned). The prop is on nice and tight, too. I read Mark Matthews post from 2002 here on cavitation re: leading edge damage and pitting. The leading edge of the prop looked fine, too.

Does anyone have any ideas?

Thanks in advance,

Brad

[JiffyLube]

Originally Posted by nightowle

Today the prop consistently cavitated as I accelerated my boat just beyond 4.90 knots. I have a 1975 O'Day with an Atomic 4 engine. I do not have a tach set up to the engine yet, so I won't be able to tell you exact rpm's this is happening at. But I normally can do upwards of 6 knots. The boat had been recently hauled in May and the prop looked fine and has been performing very well since leaving in June for an extended cruise in the Gulf Islands of BC. New zincs were installed in May, as well. We dove the boat back at the dock today, and noticed no changes other than some minor algae (which we cleaned). The prop is on nice and tight, too. I read Mark Matthews post from 2002 here on cavitation re: leading edge damage and pitting. The leading edge of the prop looked fine, too.

Does anyone have any ideas?

Thanks in advance,

Brad

The problem could be before the prop. Check everything from the shaft to the motor mounts.