Slow motion video of my engine and shaft vibration

[smitty477]

I am sure they did that, but I suppose they might have not done the rotation with no reason to believe the shaft was bent. I am hoping they simply made a mistake as the thought of dealing with another bent shaft kinda sucks!

I believe there is only one way to do it right - and they already had a bent shaft on the other engine as a guide after all.
I don't know about anyone else but once I am going to the trouble of cracking those coupling bolts I am certainly going to do the complete job.
Unsure why they checked this anyway as you did not asks them to based upon your posts so far.
If the shaft is bent my thoughts are that it was not bent prior to these past events.
So asking them what they did may have them confirm that.
Choice "A" - they did not do a complete check in the first place
Choice "B' - they did do a complete check so what happened between when they checked and when you were able to use the boat first.

 

[Comodave]

Personally, I would put this problem in their court. If you did not tell them to align the port engine, then they took this on by themselves. I would tell them that it was good before they worked on it, they were not authorized to work on it, so nw they need to fix it.

 

[twistedtree]

So if I follow this, port engine had no vibration when you started down this path.

As part of the stbd work, they checked the port alignment and found it to be way out. They realigned it, and now it vibrates badly.

All this suggest that for whatever reason, their assessment that the port side was way out of alignment was incorrect, and that their realignment induced the vibration. Not sure why they found it to be so far out, but this seems to be the most likely thing.

I think Ski is right that there is no need to panic. Unless they somehow bent the shaft handling the boat, this is probably just a simple mistake that was made. I suspect that a re-check will show an engine way out alignment, and re-aligning again will restore it to it's previous performance.

 

[MichaelB1969]

So if I follow this, port engine had no vibration when you started down this path.

As part of the stbd work, they checked the port alignment and found it to be way out. They realigned it, and now it vibrates badly.

All this suggest that for whatever reason, their assessment that the port side was way out of alignment was incorrect, and that their realignment induced the vibration. Not sure why they found it to be so far out, but this seems to be the most likely thing.

I think Ski is right that there is no need to panic. Unless they somehow bent the shaft handling the boat, this is probably just a simple mistake that was made. I suspect that a re-check will show an engine way out alignment, and re-aligning again will restore it to it's previous performance.

Just spoke to the yard. They spent another 6 hours (not billed) to remedy the issue. They said it is better, but I don't think it has been eliminated. In fact, my strong assumption is that when I see it, it will probably still be serious enough that I'll want to continue to address it. Just a hunch.

I do strongly believe that they have a capable technician working on this. It is their most senior technician.

They took the boat out of the water again and checked the prop. Prop was okay. They checked the shaft. No runout. Shaft was fine. They checked the cutlass bearing. It was fine.

They put it back in the water and disconnected the coupling completely and it was supposedly really easy to move the engine around as the mounts are very soft.

So they tried again to align it, and whereas last time they aligned it and it was off by 6 thousandths, it is now 3 thousandths. Yet there is still vibration. Actually, more of a shake like before. But they said it is much better. We'll see if it is truly "much better" when I see it for myself.

They also called the local Volvo shop (Helmut's Marine) and conferred with them.

I also called the guy who serviced my Volvos about a month ago. The one thing he could think of is that he said he's seen a few cases of where the facing of the coupler is off, in which case it wouldn't matter how much time they spent trying to align it, as it would still be off. He said he's seen instances where it is fine, but if you move it even one bolt hole over on the coupler, it can then be off. I may have lost a bit of detail in my translation, but hopefully you get the gist of it.

Thanks,
Mike

 

[smitty477]

"He said he's seen instances where it is fine, but if you move it even one bolt hole over on the coupler, it can then be off. I may have lost a bit of detail in my translation, but hopefully you get the gist of it."


Hello Mike - that is why you mark the flanges before you loosen any bolts. I use a file mark on each one but there are many other ways to quickly mark the flanges.

 

[MichaelB1969]

"He said he's seen instances where it is fine, but if you move it even one bolt hole over on the coupler, it can then be off. I may have lost a bit of detail in my translation, but hopefully you get the gist of it."


Hello Mike - that is why you mark the flanges before you loosen any bolts. I use a file mark on each one but there are many other ways to quickly mark the flanges.

AGREED!!!!

Now I am wondering if there is an issue with the flanges. When the boat was grounded, both props got mangled. Obviously, the starboard shaft was bent. But I wonder if the port shaft impact knocked the flange itself so that it isn't perfectly square. Hmmm.

 

[Art]

Bottom line seems to be: Port engine had no vibration/shake before the yard technician began to mess with its alignment... while not being authorized to do so by you... correct?


He or another at the marina never asked you if they could check your port engine for alignment, and, if they desired to do so could perform a realignment... correct?


If both those are so; then it seems they are who needs to rectify and make things as smooth running as was previously the case.


It could be: In some way the port drivetrain somehow got tweaked during the grounding. And, that some smart alignment technician knew how to overcome the problem and got the drive line operating well together. When the technician in this yard did an unauthorized attempt to "better" align the port drive line he unknowingly undid what previous tech has smartly put into place.


Hope this alignment nightmare soon ends for you!

 

[Ski in NC]

Are you sure the port was silky smooth before the work? Your focus may have been on the other one which was presumably worse.

Gear flanges can have runout. Dealt with that a few times. Easy to measure, not so easy to fix.

And yes, if you have soft mounts, it takes very little being "out" to set up a vibe.

Try different rpms. If the vibe exists only at one rpm, smooth otherwise, and the vibe rpm is not cruise, then might live with it.

 

[MichaelB1969]

Are you sure the port was silky smooth before the work? Your focus may have been on the other one which was presumably worse.

Gear flanges can have runout. Dealt with that a few times. Easy to measure, not so easy to fix.

And yes, if you have soft mounts, it takes very little being "out" to set up a vibe.

Try different rpms. If the vibe exists only at one rpm, smooth otherwise, and the vibe rpm is not cruise, then might live with it.

I am pretty sure I would have noticed it being like this before, but who knows. Anything is possible. I'm going to check it out tomorrow and my broker (who is also a surveyor) is coming with. Will let you know what happens.

Thanks,
Mike

 

[MichaelB1969]

Here is a status update for anyone curious. I took the boat out this weekend and it is definitely much better than it was. I was with my son and had him take the boat through the entire rev range in 100 rpm increments all the way to full throttle.

The engine shake is much less severe, and only happens in a very narrow rpm range. Seems to happen around 900 - 1,100 rpm. Once you get to around 1,300 - 1,400, it disappears completely, and under 900 rpm it isn't all that evident either. For reference, I am usually cruising between 2,000 - 2,500 rpm (10 - 14 knots).

So I think what I am going to do is simply try to enjoy using the boat since we are getting into the best time of year here in the Bay Area (Sep and Oct), and then once the season is over I will probably take it to a different yard that is also an authorized Volvo service center and have them take a look to determine if I should do anything further with it.

Interestingly, when I look at the movement of the shaft where it passes through the seal, it looks like a vertical up and down movement. Not sure if this means anything, but here is what it looks like around 900 - 1000 rpm (first part of the video at normal speed, second part in slow motion 240 fps):

https://www.icloud.com/sharedalbum/#B0g5VaUrzM1kTu

 

[Art]

Sorry to say, that seems quite a bit of movement to me. Keep your eye on it! Enjoy the summer!