I have a '88 Yami 200HP 6 Cyl "Precision Blend" with which I am having two issues. I'll outline one here, and the other issue on another post.

I have a SS prop. I had the boat out on big water a couple weeks ago, 4 to 6 foot swells. Every time the bow would come down "heavy", the motor would act as if the prop was losing grip in cavitation. The RPMs would skyrocket, and the boat would stop moving until I would back off the throttle, and ease it back up.

I attributed this to some weird phenomenon due to my boat's configuration - it's got an extremely "stepped" hull, and I thought maybe that in combination with the big waves was causing cavitation.

But then I had it out on not-so-big water a few days later. While the motor performed much better, it did "lose grip" a couple times, in just the same way as before.

Question: Can anyone tell me definitively what's going on here? I've been told it's possible that the prop needs to be rebuilt - that the plastic ring that's supposed to "give" if you hit rocks may be causing the hub to slip - and I have dinged the occasional rock .

Does it sound like that to any of the experts here, or is it a simple cavitation problem that I can chalk up to having an old boat with a weird hull?