Is this normal? Shaft movement- short video

[SoWhat]

Agree with all previous suggestions that the shaft/transmission coupler alignment needs to be redone. All 4 engine mounts are tweaked so that couplers are parallel. If that doesn't solve the problem then the shaft needs to be removed for straightening. I'd replace the bushings while shaft is out. Not an emergency but I wouldn't wait until next season.

 

[psneeld]

With or usually before a shaft pull/check is a good check of a properly balanced prop.

 

[tiltrider1]

Like others have said, we don’t know if the job was done correctly. If I had been told that the boat had 5 or 10 hours since being worked on I would have said too much wobble for something just done. It is possible that the boat has taken on some distortion for being on the hard for so long but it is more likely that the boat was blocked wrong and was distorted when the shaft was hooked up.

 

[Comodave]

You may even have to pull the shaft and verify that the strut was installed properly. They can take a wire and put in in place of the shaft or use a laser to make sure it is aligned correctly. But start with the simple stuff first. The grounding may have been much more severe than you were led to believe. Unfortunately you never had the chance to run the boat before the grounding. And maybe they sold the boat because of the grounding and subsequent repairs. Who knows???

 

[mvweebles]

You may even have to pull the shaft and verify that the strut was installed properly. They can take a wire and put in in place of the shaft or use a laser to make sure it is aligned correctly. But start with the simple stuff first. The grounding may have been much more severe than you were led to believe. Unfortunately you never had the chance to run the boat before the grounding. And maybe they sold the boat because of the grounding and subsequent repairs. Who knows???

It happens. 25 years ago, my wife and I owned a Newport 28 sailboat with 12hp Universal diesel. We tried every which way to align the engine. Turns out the strut was not aligned - not even close. No visible damage so my guess is it wasn't installed properly in the first place.

Good luck.

Peter

 

[mncruiser]

You may even have to pull the shaft and verify that the strut was installed properly. They can take a wire and put in in place of the shaft or use a laser to make sure it is aligned correctly. But start with the simple stuff first. The grounding may have been much more severe than you were led to believe. Unfortunately you never had the chance to run the boat before the grounding. And maybe they sold the boat because of the grounding and subsequent repairs. Who knows???

The boat was sold because the owner passed away. It sat for two years while he was sick, he paid for work to be done up until a month before he passed away, like he was going to be back boating. His widow accepted my purchase agreement a week after he passed away. Sad.

The preventive maintenance he did was phenomenal. You name it, it was done. New fuel tanks just because? Done in 2014. The unfortunate grounding in 2018 was a huge embarrassment to him, but again I have all the work orders, to me he went above and beyond to make things right. I’ve got ridiculous stacks of receipts from his 2 marinas in Charlevoix and in OH when he had the boat there. They provided me everything. It was amazing to see it all.

Gotta do some more digging. Unfortunately they are occupied launching boats like crazy.

We think the shaft may not have been replaced but repaired. Trying to verify that today.

Thanks for all the comments.

 

[Comodave]

The shaft may have been straightened. Maybe the machine shop didn’t do it right???

 

[mncruiser]

The shaft may have been straightened. Maybe the machine shop didn’t do it right???

Verified today the shaft was new in 2018. Took the boat out today with the captain that helped me deliver it last spring, 50 hours from Charlevoix, MI to Bayfield.

Right or wrong, the boat feels the same it did the delivery trip, and all last season. No large vibrations. Still the somewhat noticeable shaft movement….that I guess I didn’t catch.

We know it’s not right, so an alignment is In order. The tech stopped by and nothing obvious looks wrong, but he had about 3 minutes to spare. Further inspection in about a week. I did take a video at 9 kts. Will post it later.

 

[mncruiser]

Verified today the shaft was new in 2018. Took the boat out today with the captain that helped me deliver it last spring, 50 hours from Charlevoix, MI to Bayfield.

Right or wrong, the boat feels the same it did the delivery trip, and all last season. No large vibrations. Still the somewhat noticeable shaft movement….that I guess I didn’t catch.

We know it’s not right, so an alignment is In order. The tech stopped by and nothing obvious looks wrong, but he had about 3 minutes to spare. Further inspection in about a week. I did take a video at 9 kts. Will post it later.

Took a video but the quality is poor.

 

[mncruiser]

I suggest you do a simple diagnostic measurement. This will tell you what is happening without taking the boat out of the water.

1 Using a dial gage (also called dial indicator), measure the runout* of the shaft close to the dripless (!) seal. Do this with the engine not running, turning the shaft by hand.

2 Then loosen the bolts on the shaft coupling at the back of the gearbox and repeat the runout measurement.

If the runout is the same in both cases, this implies a bent shaft.

If the runout goes away in step 2, this implies that the coupling is causing the runout (the coupling is not square on the shaft).

.

Nick, thanks for the procedure.

When you loosen the bolts in step 2, how does the shaft not flop around as you turn the shaft? Or I’m just not understanding the process….

Thanks

 

[Comodave]

Loosen, not remove the bolts.

 

[mncruiser]

Loosen, not remove the bolts.

Loosen how far? If they are loose, won’t the shaft just flop around?

 

[Nick F]

Loosen just enough so that you can turn the nuts by hand (maybe one turn). There is a protrusion on shaft side of the coupling which engages into a matching bore on the gearbox half of the coupling. So long as this protrusion is at least partly engaged the forward end of the shaft will be supported (concentric with the gearbox coupling).

When you turn the coupling the (loosened) bolts will still make both halves rotate together.

Regards,
Nick

 

[Comodave]

It is called a pilot.

 

[boatnbump]

https://www.yachtsurvey.com/Alignment2.htm

read this article. The first step to a shaft replacement is a new cuppling and trueing it to the shaft. If they used the old cuppling you are back at first base.

 

[JRO]

You don’t have any. It’s fine.
You “feel” and hear shaft/prop issues (in the boat) as you move through the water. It might get noticeable at a particular or different RPMs. If it’s bad… It will clearly tell you.
Mix yourself a cocktail and stop worrying.

 

[Raduran]

From the naked eye it looks fairly bad. Maybe put a dial gauge, not sure that is the correct name, on it to see how much it is actually moving. It can be a fairly involved job to make sure the shaft is running true. You can take it to a machine shop to see if it is straight. But it could also be the cutless bearings are not in line. But the easiest thing and the first thing I would do is check the engine alignment and see if that fixes the problem l. But I wouldn’t let it go for very long.

During the survey of the boat we're in the process of buying our surveyor noted a similar movement in a shaft. At the haul out it was noted that a cutlass bearing needed replacing. Based on the shaft anode (zinc) that had slide down to the bearing, he believes the bearing over heated due to the lack of water flow around the bearing. In short, you can lose a bearing prematurely. Best check it out sooner than later.

 

[Comodave]

One of the boats we bought had the short clearance anode on the shaft, they are squared of instead of teardrop shaped. There was about 3’ of shaft space available for the anode but they had it installed right in front of the curless bearing. No idea why they did that but I put on the teardrop anodes and moved it forward some so it couldn’t interfere with the water flow into the cutless bearing.

 

[Bob M]

Because the new ZF/Hurth transmissions were 4" shorter than the obsolete Volvo transmissions, longer custom made driveshafts were required, which incidentally were more expensive than the new transmissions.


Both driveshafts were installed and vibrated excessively. They were bent. Ordered round two: same problem. Ordered round 3: same problem but only one of the shafts vibrated. Ordered round 4: vibration problem resolved, after 3 1/2 years.


Lesson learned: new driveshafts aren't always straight driveshafts.

 

[Comodave]

Because the new ZF/Hurth transmissions were 4" shorter than the obsolete Volvo transmissions, longer custom made driveshafts were required, which incidentally were more expensive than the new transmissions.


Both driveshafts were installed and vibrated excessively. They were bent. Ordered round two: same problem. Ordered round 3: same problem but only one of the shafts vibrated. Ordered round 4: vibration problem resolved, after 3 1/2 years.


Lesson learned: new driveshafts aren't always straight driveshafts.

Did they try to straighten any of the shafts?

 

[Bob M]

Yes, but the effort failed.

 

[Comodave]

That is too bad. Did the supplier eat the installation costs?

 

[adornato]

Tutorial on shaft alignment from steve d'antonio

there is a 2 part excellent article free online from steve d'antonio.
here is link to first part

https://stevedmarineconsulting.com/the-ins-and-outs-of-engine-and-shaft-alignment/

second part follows.

 

[Bob M]

The supplier ate the cost. So did the mechanics, who had to: repeatedly haul the boat; remove one of the rudders that blocked removal of one of the driveshafts; remove the driveshafts, install new driveshafts, reinstall the rudder; realign the engine; and get sent back to the drawing board by failed the sea trials.



My wife and I ate the cost of parking (1 year on the hard, 2 1/2 in the water) and insuring a boat that we couldn't cruise for 3 1/2 years.


We were warned about Volvo engines before we bought the boat and I researched parts availability for the 1987 engines: expensive, but available. These diesel engines run like they'll last forever. What I didn't research was the Volvo transmissions. Parts are not available.

 

[Comodave]

Well at least you didn’t have to payfor everything. I believe that there were some class action law suits over the Volvo transmissions.

 

[Bob M]

Haven't heard of any class action suites regarding Volvo MS4A transmissions.

 

[Steve DAntonio]

That type of lateral movement can be caused by a few things.

The shaft is not centered in the coupling. That's a machining error.

The shaft coupling is not centered on the transmission flange pilot bushing (normally not possible unless it's damaged or defective).

As someone else noted, it can be measured with a dial indicator, if it is most pronounced near the coupling, it's almost certainly one of the two issues mentioned above.

For more on couplings see https://stevedmarineconsulting.com/wp-content/uploads/2019/06/ShaftCouplings179FINAL-PBB.pdf

 

[Capn Bob]

Agree that while the wobble is not extreme, it should be addressed. Not good for the trans.

 

[JRO]

How many actual cruising hours (through the water) were traveled before the video?

 

[Comodave]

Haven't heard of any class action suites regarding Volvo MS4A transmissions.

I don’t know which Volvo transmission it was, it was a long time ago.