View Full Version : hit log, have vibration, need advice
08-19-2009, 08:12 PM
I was out for a little wakeboarding yesterday evening on my '04 Outback DD and returning to the landing at a hair over idle when I apparently hit a log under the water (river has been low and there was no way to know it was there. The engine stopped, but started again right away. In any case, from my inexperienced inspection, I cannot see any damage to the drive shaft, strut, or rudder; however, the propeller appears to be slightly bent on at least one of the blades. Now I'm getting pretty strong vibration at 15mph and up. Idled a couple of miles back.
My questions are as follows:
1. Is it possible that only a slightly bent prop could cause so much vibration?
2. If I used a fake-a-lake, would I be able to verify that the drive shaft + strut are not bent? I figure I ought to be able to see if it vibrates the same out of water. Maybe even hold a pencil against the shaft while it's running to see if it bounces off at all?
3. Any advice you guys can offer?
Finally, I fear that in this economy, boats don't sell well and I'm scared of the dealer ripping me off because they're not making any money.
Thanks in advance - I've read a lot of posts on this forum and you guys seem to really know what you're talking about.
08-19-2009, 08:20 PM
I did about the same thing right after I bought my boat. Could not even tell there was any damage to the prop, but apparntly it knocked it out of balance. Had a very bad vibration at any speed over idle. So to answer one of you questions, yes a slight bend in the prop will cause a bad vibration.
Sent mine off for repair and $89 later all is well. Did get a spare though.
Hope this helps some.
08-19-2009, 08:43 PM
dealer told me the same thing when we had a rope wrapped around the shaft. thought the prop might have been bent and they quoted me $95 to send it in to get re-balanced. takes a couple weeks from what I was told. our dealer will offer a spare in the meantime for free. may not be the exact one you have, but keeps ya on the lake. your dealer might offer the same thing, or maybe a rental..
One quick way to check for prop shaft damage is to (with the boat out of the water and in nuetral with the key in your pocket) is to turn the shaft by hand. It should turn easily with no binding. If you turn it and it is easy then hard or hard all the time then the shaft is most likely bent.
And it doesn't take much of a ding at all to cause vibration. Look at it this way the prop is kind of little (ok I live on the coast and when I take my prop to the prop shop here it is actually dinky compared to the props this guy repairs) but when you think it takes 300+ hp to turn this thing then you can understand the magnitude of a little ding. Look at it this way one little blade is worth 100hp! So a little ding can have a big effect.
08-20-2009, 11:27 AM
I bumped a tree in 28 feet of water right after my boat was new. I went underwater and couldn't tell that there was anything wrong. Took it to the dealer and it had bent the strut, and prop. It doesn't take much and any vibration means something is out of alignment. It will be worth having it looked at since you don't want to run it with that vibration and take a chance of it messing something in the transmission.
08-20-2009, 11:41 AM
Thanks for all the suggestions. I'm going to try the hand-turning of the shaft tonight, make sure that works as expected. I'm also sending the propeller off for repair to the shop the dealer uses.
I guess my only remaining fear is that if I find that that the shaft turns as expected (easily and evenly), and also if after the prop repair, the boat doesn't vibrate anymore - is there any reason to fear that anything else is out of whack that I'm not noticing? In other words, can I save the money I would otherwise spend having the dealer inspect it?
Thanks again guys!
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