Possible Cavitation?

We are thinking now that perhaps my afore listed problem was a cavitation- any thoughts? Just to recap at about 25 MPH a left turn was attempted but instead of turning caused the stern to come up out of the water and the boat continued to travel striaght. The stern coming out of the water was just enough to cause a lot of spray to come into the boat soaking my buddy who was still in dress clothes form work. We made 100 turns after that one indicent and were unable to reproduce the event. The steering system was inspected and no problems were detected. Any thoughts are greatly appreciated.

Sounds like "chine lock." I haven't experienced it myself but I've heard of it. Some hulls are worse than others for it. I understand that a twisted hull is more likely to do it. I don't know if '79 Ski Nautiques are likely to experience this but I guess fiberglass hulls can change shape a bit over time on a trailer so maybe your hull is more prone to it now.

I don't know the exact mechanism but I guess it's sort of akin to when a stunt man drives a car up on two wheels. The rudder just keeps the boat rolled over and the boat rides straight with the new running surface being only one half of the normal running surface.

Does this sound right? Did the boat roll over to port when this happened?

Actually my buddy driving was about 120 pounds lighter than the guy sitting opposite him and there was a hell of a pitch to his side. So perhaps that had somehting to do with it combined with exactly what you were all thinking. Either way I guess I wont worry about it.