Reply
 
Thread Tools Display Modes
 
Old 04-04-2013, 10:26 AM   #1
Guru
 
Tom.B's Avatar
 
City: Cary, NC
Country: USA
Vessel Name: Skinny Dippin'
Vessel Model: Navigator 4200 Classic
Join Date: Jul 2009
Posts: 5,152
Drive Saver: Yay or Nay

After being on the hard for 3+ months, we developed a vibration in the boat. Bess noticed it first and I wrote her off as crazy since we had not been on the boat in a while and she had just lost her Mojo (and to her affinity for things that vibrate ). Well, last weekend when I was running the motor up to temp in the slip, I had a chance to take a look at the prop shaft (and it was making a funny noise). When I looked at the stuffing box, it was wobbling around about a 1/2" each direction. That, we then knew, was the source of Bess' mystery vibration. (apologies followed )

Since I was not 100% sure what was going on, we got a professional from the local boat yard to come have a look. Turns out that the Drive Saver - that red urethane disc between the transmission output and the shaft collar, had slipped off of center. Primarily due to the previous owner's use of flat washers between disc and plates.

The tech mentioned that he prefers NOT to use Drive Savers. Most notably because we are a single screw with a protected prop. "They cause more problems than they fix.", he said. The validity of that is a bit suspect because, as a tech, he only sees the BAD things that happen and may not see all the props and/or transmissions saved by them. Anyway, I am getting off the point.

After he removed the washers and reset the Drive Saver in place, all seemed somewhat back to normal. And like all things boating, good news always comes at a price. The shaft still had a slight wobble to it. He broke out the dial gauge and we do, indeed, have a bent shaft. Withing the part of the shaft he could get to, we are out by .012". Spec calls for .010" as a max, so we are just barely outside of that, but we can't see the entire shaft and could be way off down the tunnel. He has recommended that it CAN wait a little while, but we need to do it in the Fall at the latest. Considering that our 2" drop Velvet drive is no longer made, but can be rebuilt, we will probably do it mid-summer before the shaft start destroying the transmission beyond repair.

So I guess you are wondering what my question is? Well, since we will be ordering a new shaft, should we plan on replacing or removing the Drive Saver? I don't know. The little voice says to use it, but at $500 to replace, that seems like a lot for hunk of polyurethane that a 15-year marine mechanic doesn't recommend.

Tom-
__________________
Advertisement

__________________
2000 Navigator 4200 Classic
(NOT a trawler)
Tom.B is offline   Reply With Quote
Old 04-04-2013, 10:46 AM   #2
Guru
 
Phil Fill's Avatar
 
City: Everett Wa
Country: US
Vessel Name: Eagle
Vessel Model: Roughwater 58 pilot house
Join Date: Oct 2007
Posts: 2,919
Its fix so why change? Besides a new shaft is going to cost a couple of grand. plus the cost of installation and the yard.
__________________

Phil Fill is offline   Reply With Quote
Old 04-04-2013, 11:12 AM   #3
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,707
Tom B,
I'd remove the shaft and have it straightened. Don't watch them do it. No shaft is straight. Some are just straighter. When you buy a new shaft you need to have it straightened. Find a shop that does a lot of boat shafts. Get a new "shaft saver" and carefully inspect your coupling/s, intermediate bearings, stern bearing (cutlass) and any other related hardware that requires shaft removal. The Shaft Saver is not something I'd recommend for general service but it's OK. It's not a flexible coupling but a weak link to protect the shaft when you hit something w the prop like a rock. Install everything carefully according to manufacturers specs.

If you really want to get rid of the Shaft Saver get a cutoff piece from the shaft shop and properly mate it w a coupling and have all cut to size. Couplings are fine. Get the type that are basically tubular and clamp w many socket head cap screws. I thought of them as Mickey Mouse band aids until I used one.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 04-04-2013, 11:28 AM   #4
Guru
 
Brooksie's Avatar
 
City: Cape Cod, MA
Country: USA
Vessel Name: Island Seeker
Vessel Model: Willard 36 Sedan
Join Date: Oct 2007
Posts: 954
Have them on my boats and never had a problem. They do serve a purpose but are not a substitute for a good alignment. I would continue with one. I don't understand where the PO put the washers, but did that ruin the Drivesaver? By all means have the shaft straightened if it can be and it sounds like it can.
Brooksie is offline   Reply With Quote
Old 04-04-2013, 11:40 AM   #5
Guru
 
Tom.B's Avatar
 
City: Cary, NC
Country: USA
Vessel Name: Skinny Dippin'
Vessel Model: Navigator 4200 Classic
Join Date: Jul 2009
Posts: 5,152
I am totally planning on doing the majority of work myself. Shaft removal and re installation doesn't look like rocket surgery to me. However, I will probably bring in the pro to just make sure it's lined up correctly when it goes back in.

John, the washers were on both sides of the Drive Saver on every bolt. I have the manual for it and there are no washers shown at all. So how the PO decided to put them in is beyond me.

Thanks for the tips. The yard said they don't like to straighten shafts (actually send them out to be done), but if I can find a place to do it, I will go that route for sure.

Tom-
__________________
2000 Navigator 4200 Classic
(NOT a trawler)
Tom.B is offline   Reply With Quote
Old 04-04-2013, 11:43 AM   #6
Guru
 
Tom.B's Avatar
 
City: Cary, NC
Country: USA
Vessel Name: Skinny Dippin'
Vessel Model: Navigator 4200 Classic
Join Date: Jul 2009
Posts: 5,152
NICE!

__________________
2000 Navigator 4200 Classic
(NOT a trawler)
Tom.B is offline   Reply With Quote
Old 04-04-2013, 11:47 AM   #7
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,707
Oh yes ......

Shaft runout varys greatly w length.

Find a good shop Tom.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 04-04-2013, 11:48 AM   #8
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,868
...have no clue how he could have done an accurate shaft straightness alignment with it in the boat as shafts sag....that's why alignments are just a guess on most boats...I'd go with a new drivesaver if I were you unless you are willing to go through buying a new shaft or having a machine shop try to make an inset/longer coupling.

If most of the problem went away when the drivesaver was redone...why think it is also a shaft problem?
psneeld is offline   Reply With Quote
Old 04-04-2013, 12:18 PM   #9
Guru
 
Tom.B's Avatar
 
City: Cary, NC
Country: USA
Vessel Name: Skinny Dippin'
Vessel Model: Navigator 4200 Classic
Join Date: Jul 2009
Posts: 5,152
After he re installed the Drive Saver, the prop still had a small wobble to it, so he suspected a warped shaft.

I specifically asked if an out-of-alignment engine would cause it to do that. He said no. He was 99% sure it's a bent shaft. Yes, he acknowledged the measurement *could* be off a bit because it's in the boat, but that it's usually a pretty good indicator.

The current plan it to possible do a short haul over the summer. Pull the boat without blocking it and pull the shaft to check for straight. If it's straight, re install and drop back in the water. If not, block it up and spend a week or so fixing it.
__________________
2000 Navigator 4200 Classic
(NOT a trawler)
Tom.B is offline   Reply With Quote
Old 04-04-2013, 12:36 PM   #10
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,868
an out of alingnment engine will cause wobble....but what you have in mind is probably a good route...
psneeld is offline   Reply With Quote
Old 04-04-2013, 12:42 PM   #11
Guru
 
City: Hotel, CA
Country: Fried
Join Date: Sep 2011
Posts: 8,328
Call local machine shops Tom. Any machine shop worth its salt can straighten the shaft.

When is the last time the prop was off the shaft? Everything properly torqued?

Just a couple outside the box questions is all...
__________________
Craig

It's easier to fool people than to convince them that they've been fooled - Mark Twain
CPseudonym is offline   Reply With Quote
Old 04-04-2013, 12:42 PM   #12
Guru
 
Tom.B's Avatar
 
City: Cary, NC
Country: USA
Vessel Name: Skinny Dippin'
Vessel Model: Navigator 4200 Classic
Join Date: Jul 2009
Posts: 5,152
Quote:
Originally Posted by psneeld View Post
an out of alingnment engine will cause wobble
That's what I thought too, but AT the transmission end, it reads almost true (or within spec anyway). Back three feet from there, it's out by the measured .012". Does that mean anything?
__________________
2000 Navigator 4200 Classic
(NOT a trawler)
Tom.B is offline   Reply With Quote
Old 04-04-2013, 12:45 PM   #13
Guru
 
Tom.B's Avatar
 
City: Cary, NC
Country: USA
Vessel Name: Skinny Dippin'
Vessel Model: Navigator 4200 Classic
Join Date: Jul 2009
Posts: 5,152
Quote:
Originally Posted by CPseudonym View Post
When is the last time the prop was off the shaft? Everything properly torqued?
Since before I bought it 4 years ago and I am guessing at least a year or more before that.

Had a diver on it too last weekend. He checked, double-checked, shook and spun the prop. Gave the in-water gear two thumbs up.
__________________
2000 Navigator 4200 Classic
(NOT a trawler)
Tom.B is offline   Reply With Quote
Old 04-04-2013, 12:54 PM   #14
Guru
 
City: Hotel, CA
Country: Fried
Join Date: Sep 2011
Posts: 8,328
Our boat had a small vibration starting at about 2,000 rpm when we purchased it. I'd been running around since the purchase at 1,800, basically choosing to live with it until I could dive and inspect the prop for nicks or dings.

Tuesday I took it out and ran it up to 3,500 for 2 miles and no vibration at all. Made me wonder if the packing had taken a set during the last year of limited use? Ran the rest of the day at 2,200 with no vibration

It just went away???
__________________
Craig

It's easier to fool people than to convince them that they've been fooled - Mark Twain
CPseudonym is offline   Reply With Quote
Old 04-04-2013, 01:50 PM   #15
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,868
Quote:
Originally Posted by Tom.B View Post
That's what I thought too, but AT the transmission end, it reads almost true (or within spec anyway). Back three feet from there, it's out by the measured .012". Does that mean anything?
Not sure...have to start someplace with a known or a strong assumption.

On the surface it sounds like the shaft could be bent...but how all of a sudden?

Assunimg that everything was OK before the drivesaver slipped...something sounds fishy.

Do you align the coupling to the drivesaver or the drivesaver to the tranny flange?
psneeld is offline   Reply With Quote
Old 04-04-2013, 02:50 PM   #16
Guru
 
Tom.B's Avatar
 
City: Cary, NC
Country: USA
Vessel Name: Skinny Dippin'
Vessel Model: Navigator 4200 Classic
Join Date: Jul 2009
Posts: 5,152
Quote:
Originally Posted by psneeld View Post
On the surface it sounds like the shaft could be bent...but how all of a sudden?

Assunimg that everything was OK before the drivesaver slipped...something sounds fishy.
I know that it got out of keester big time while on the hard. I understand boats change shape when they are out for a while and may not always go back to 100% correct. So I believe the weak point was the drive saver connection that slipped during haul-out. Now, as for the current, post technician, wobble we see *COULD* have been there all along. I never noted it when I had adjusted the stuffing box in the past. Did it wobble before? Yea, maybe, but I am not sure. So it may not be all of a sudden. We could have hit a log in the river on our way home, but I would THINK a prop hit that could bend a 2.5" piece of hardened steel would be pretty noticeable. I mean it's a pretty small wobble now and apparently something we can live with for a little while.

Your second question I didn't understand fully.

Tom-
__________________
2000 Navigator 4200 Classic
(NOT a trawler)
Tom.B is offline   Reply With Quote
Old 04-04-2013, 03:25 PM   #17
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,707
Any machine shop can beat on a shaft but only a good one that does lots of boat shafts can straighten it.

Straightening boat shafts is part science but mostly experience and skill.

I know this because I worked at a good one for 14 years.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 04-04-2013, 04:09 PM   #18
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,868
Quote:
Originally Posted by Tom.B View Post
I know that it got out of keester big time while on the hard. I understand boats change shape when they are out for a while and may not always go back to 100% correct. So I believe the weak point was the drive saver connection that slipped during haul-out. Now, as for the current, post technician, wobble we see *COULD* have been there all along. I never noted it when I had adjusted the stuffing box in the past. Did it wobble before? Yea, maybe, but I am not sure. So it may not be all of a sudden. We could have hit a log in the river on our way home, but I would THINK a prop hit that could bend a 2.5" piece of hardened steel would be pretty noticeable. I mean it's a pretty small wobble now and apparently something we can live with for a little while.

Your second question I didn't understand fully.

Tom-
Not sure of your setup...but I'm guessing an outer cutlass, and inner cutlass, shaft coupling, drivesaver, tranny flange.

If the inner cutlass is worn you can have a lot of shaft whip depending on length...but that's not what it sounds like to be out so close to the tranny. ...plus you would probably hear some noise from it. If the engine didn't really go anywhere and just needed a minor alignment after readjusting the drivesaver...and everything else is squared up...then the shaft would be uspect especially if even a rough runout showed it...but the runout is not very important while the shaft is in the boat as stressors could just have it deflected.
psneeld is offline   Reply With Quote
Old 04-04-2013, 06:56 PM   #19
Scraping Paint
 
City: -
Country: -
Join Date: Oct 2007
Posts: 13,748
A few years ago we had one shaft straightened and one replaced. We also chose at this time to get rid of the stock but too-small shaft couplers and replace them with bigger, heavier-duty, split couplers which do a much better job of helping to keep the shafts in alignment.

While we never considered shaft savers, I have heard several negative things and owner reports about them but never any positive ones. In one case a prop strike broke the shaft saver as advertised but the shock still sheared two engine mounts.

So based solely on what we have heard we would never bother with them. The investment we made in the new, big split couplers, however, was well worth it.
Marin is offline   Reply With Quote
Old 04-04-2013, 09:23 PM   #20
Guru
 
Besslb's Avatar
 
City: Cary NC
Country: USA
Vessel Name: Skinny Dippin'
Vessel Model: Navigator 42'
Join Date: Oct 2009
Posts: 683
Quote:
Originally Posted by psneeld View Post
Not sure of your setup...but I'm guessing an outer cutlass, and inner cutlass, shaft coupling, drivesaver, tranny flange.
Does this help??
Attached Thumbnails
Click image for larger version

Name:	Shaft Saver.jpg
Views:	89
Size:	110.7 KB
ID:	17782  
__________________

Besslb is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 11:07 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012