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thwack
07-04-2010, 12:07 AM
06' X-15 :confused:

I was running down the river today at about 35mph when my boat all of the sudden started vibrating heavily. I didn't hit anything and after pulling the boat out of the water, there doesn't seem to be anything warped and the prop is all in tact and looks fine. I had to run all the way back to the dock at 8mph. Anthing over that and the boat was vibrating pretty seriously. It's the middle of the summer and I have no idea what I have to do to get back in the water. Any thoughts? Ideas?

JLeuck64
07-04-2010, 03:29 AM
Check the prop shaft alignment...

Jerseydave
07-04-2010, 09:02 AM
Does the engine run smooth in neutral?

Assuming it only vibrates when its in gear, check your flange bolts on the prop shaft, look for a bent prop shaft or bent prop. You may have hit something and not realized it. It doesn't take much to throw a prop out of balance. If you have a good spare prop, put it on and take the boat out again to see if you're vibration is gone.

thwack
07-04-2010, 10:26 AM
Yes, it only vibrates when under load. It will not vibrate in neutral or even in gear when it's out of the water. The vibration occurs when it's under load around 2000 RPMs plus. I've checked over and over the prop shaft and prop and haven't noticed any visable rippling, dings, or warps. What is the best way to check the prop shaft alignment?

jkski
07-04-2010, 10:38 AM
For whit its worth, I hit a submerged log(3" diameter) with my prop about 2 weeks ago, ending a 15 year streak of no damage mind you. In any case, the boat had a slight vibration at 3200rpm's but nothing below or above that. The prop and all underwater gear, including the hull are spotless, so I pulled the prop and sent it off to be checked. Again, it "looked" fine with not so much as a scratch, but the repair facility said it was out of balance and that each blade was off in pitch by far more than the .05 they allow for. Long story short, they put it back to where it should be and all is well.
The repair facility stated, without me saying a word, that I must have hit something at a slow speed in order to affect each blade and not actually dinged it, which is accurate as I hit the object going 20mph while pulling a wakeboarder.
As someone else mentioned, if you have a spare prop or someone can loan you one to test, that will tell you right there.
Good luck.

Shredman
07-05-2010, 03:45 PM
06' X-15 :confused:

I was running down the river today at about 35mph when my boat all of the sudden started vibrating heavily. I didn't hit anything and after pulling the boat out of the water, there doesn't seem to be anything warped and the prop is all in tact and looks fine. I had to run all the way back to the dock at 8mph. Anthing over that and the boat was vibrating pretty seriously. It's the middle of the summer and I have no idea what I have to do to get back in the water. Any thoughts? Ideas?

Check the strut bearing where the shaft goes through the strut. If there is any play in the shaft at the strut, or if the strut has play in it, that would cause what you described.

thwack
07-06-2010, 10:44 PM
Thanks for all of the input. I checked the strut bearing, shaft, prop and firing and couldn't find anything out of the ordinary. I finally realized that I don't have the time to tear into it the way I need to so now it's in the dealer's hands. Worst part of that is no boat for at least 3-1/2 weeks (of course this would happen in the prime of summer fun).

east tx skier
07-06-2010, 10:58 PM
Check the prop shaft alignment...

Plus 7. It doesn't take much. You might also check the shaft packing. I have seen that go and cause some pretty heavy vibration.

thwack
07-10-2010, 10:21 PM
Got the boat back from the dealer today. Turned out that it had about a teaspoon of water in the gas which was causing it to miss, at least according to them. Either way, they ran it, tested it, went ahead and treated the tanks and it is now running fine. Thanks for all of the input.