I had an annoying squeak years ago on my 331. It turned out to be the top of the rudder rubbing on the hull as I turned the wheel. It was a small spot that I was able to sand down. When my boat is out of the water, the rudder will slide down the rudder shaft a bit. It looks like there is plenty of room between the rudder and the hull, but when my boat goes in the water, the rudder slides up the rudder shaft and gets much closer to the hull. I noticed a bit of extra fiberglass near where the rudder shaft goes into the hull. When I sanded it down a bit, the squeaking went away.