I now have a vibration in my 92 Nauti, but only from about 1000rpm to 1250-1500rpm. After that it goes away. Doesn't occur in neutral. I am 100% certain I didn't hit anything, and there is no prop damage whatsoever. In fact the boat ran fine for 20 minutes prior to having the problem. The shaft does not seem loose, though it does move slightly when I try to force it to move. Strut seems okay too. Tranny fluid is in good shape. Any thoughts? <BR> <BR>Thanks <BR>Eric

Is the prop nut on tight? You could have reversed hard and the prop could have loosened.

Check your motor mounts and make sure your engine isn't moving around. It would be a good idea to check the alignment of the shaft to the engine, as a mis-alignment can cause what you describe. <BR> <BR>

Might want to check the prop shaft strut bushing. Just grab the drive shaft under the boat and give it a tug.....shouldn't have play in it.

It moves in the verticle plane if I giggle it, but only a little. Are you suggesting play like from front to back, or side to side? The motor does not move and the prop nut is on tight. It has take some hard reverses though. Curiously though, it ran fine for 20 minutes and then this.

From what I understand, and I may be wrong, the drive shaft should not have play in it around the strut. That is, if it is moving around in the strut when you are pulling back and forth on it, I would say that the bushing is probably worn out. (the strut what hangs down under the boat to support the shaft). That bushing is a maintenance item that is supposed to be replaced at certain intervals. At least it was for my previous boat. (89 supra comp)Also, I'm refering to it moving when you push it up and down and side to side. I doubt it would take much play to create a vibration and the faster you go, the less you might notice it. Just some ideas........

Thanks...that was the info I was looking for. It appears that I will now need to invest in a prop puller and something to remove the bushings. Me and Vince at SKIDIM are getting awfully tight this year! <BR> <BR>Eric