Cutlass bearing

Mar 10, 2014
38
Catalina 30 GYB, Sasafrass River, MD
Hello all,

Have a bronze cutlass bearing and a bronze prop shaft. Yard mechanic says cutlass bearing is shot (too much play in shaft) and that since it's shot, the shaft is most likely scored and should be replaced as well. Had a knowledgeable friend disagree with that logic and say no way I'd need a new shaft.

What to do.

Opinions on that?

Any difference on a stainless steel cutlass bearing vs a bronze one?

Better to upgrade both to stainless steel?

Ideally just a new bronze cutlass bearing but wanted some opinions on how likely a worn cutlass bearing was to cause a scored prop shaft.

Thanks!
 
Jun 8, 2004
2,841
Catalina 320 Dana Point
Can't know it's scored for sure until it's out, had the same thing on a '94 270, when pulled the bronze shaft was straight, true and unscored, it's still in that boat.
I think that was the exception to the rule however, a lot of bronze shafts get scored at the stuffing also.
They make stainless cutlass bearings ? I always thought they were a silica/bronze alloy that had some built in lubricity.
 

higgs

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Aug 24, 2005
3,627
Nassau 34 Olcott, NY
You won't know until you inspect the shaft. Use a caliper to make sure the shaft diameter is the same where it passes through the bearing as the rest of the shaft. It may not be scored, but simply worn.
 
Mar 10, 2014
38
Catalina 30 GYB, Sasafrass River, MD
Ted I'm really not sure, new to this sort of maintenance. Had the yard telling me to upgrade both to SS, wondering if they were just fishing for $ or it was worth it to see if the bronze shaft had some life left to it w/a new bronze bearing.
 
Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
Most Likely Just Fishing .............

Any difference on a stainless steel cutlass bearing vs a bronze one?
................. to see if you'll bite.

As others have said, the shaft has to come out to to inspect for scoring unless it's REALLY shot and the liner is gone.

Doesn't matter if the bearing housing is bronze or SS as it's only the nitrile rubber liner that touches the shaft.
 

Attachments

RECESS

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Dec 20, 2003
1,505
Pearson 323 . St. Mary's Georgia
If the yard told me it was shot before ever looking at it, I would not trust them to inspect it. Get someone independent to check it.
 
Jun 8, 2004
2,841
Catalina 320 Dana Point
There was nothing wrong with mine but I wanted the shaft log hose replaced and wasn't planning to haul again for 4 years so decided to do the whole driveline. The yard manager said something like "often we need to replace bronze shafts but we won't know for sure until we send it to the machinist". I believe they use a nearby machine shop that does a lot of marine work. Mine was fine and it still is 2 owners and ten years later. I think when shafts are replaced almost all are stainless now. I believe Catalina switched to stainless in manufacture around 2000. Is it better or worth upgrading against future problems ? I honestly don't know, but I think bronze shafts can and have run for decades and it takes a machinist to know if it's OK.
Actually, doesn't sound like your mechanic is too far off, he is kinda guessing that the shaft is scored or "out of true" because of the play in the bearing.
 
Mar 10, 2014
38
Catalina 30 GYB, Sasafrass River, MD
Ted Thanks for that detailed response. GuessI will just have to wait and see what they say when they tKe it out and hope they are being honest.
 
Oct 2, 2006
1,517
Jboat J24 commack
My bronze shaft lasted 40 years BUT it was a bit small in the cutlass bearing area and the stuffing box area and it was less then great were the coupling has to install


I say this because once you take it apart you will need everything and it does turn into a somewhat expensive deal

BUT after fixing everything I am sure other than a bearing at some point I am good for another 40 years :)
 
Jan 6, 2010
1,520
Chan,

Beware of what the yard says man. If this is your first foray with a boatyard, a friend's advice should be considered. That being said, my old bronze shaft was scoured at the stuffing box. My new SS shaft wasn't that expensive. Also, bronze + stray current + electrolysis need to be considered.

Another item to consider would be if changing out the shaft, also change to a PSS (or eq.) waterless shaft seal in lieu of a stuffing box. Kill two birds with one stone.

CR
 

zeehag

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Mar 26, 2009
3,198
1976 formosa 41 yankee clipper santa barbara. ca.(not there)
MAYBE THEY JUST WANT THE RECYCLE PRICING FOR THE BRONZE.
bronze stuff doesnt wear out as fast as yards WHO WANT ALL YOUR MONEY say they do.
you could well be ok, but have it micrometered
 
Sep 4, 2005
6
- - Sausalito
Maybe not so much 'greed' -

As a mechanic, if I can get you to say: "yeah; better replace it all" - then I can just cut it all out and save myself a stack of tedious dis-asssembly work. Plus; I can then work with all new and nice parts and materials. I have to do less work, make some money on the new parts, and you pay the bill. And then have zero risk in warrantying the job. It's not so much trying to gouge the customer as it is eliminating work and gauging variables.

PHM
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CalebD

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Jun 27, 2006
1,479
Tartan 27' 1967 Nyack, NY
My Cutless bearing replacement job blossomed into a full drive train job too.
While first trying to remove the shaft from the coupling (inside the boat) we discovered that the bronze shaft had become worn at the Cutless bearing point.
This simplified things immensely as we were easily (<2minutes) able to cut our bronze shaft into 2 pieces with a new Sawzall metal blade. It would have taken hours of working in the cramped space trying to push the shaft out of the bearing - very uncomfortable work.
A new hunk of 1" stainless shaft cost ~ $250 (more on this later), Cutless bearing ~ $50, new shaft log hose $10, large hose clamps $10, new stuffing box packing ~ $20. Total materials cost was well under $500 but we did all the work ourselves (except for truing the shaft - prop shop did that).

Older boats (like mine, 1967) were originally fitted with bronze shafts because bronze had been used successfully for quite some time and because the advances in metallurgy had not enabled stainless steel shafts to be common. In those days a bronze prop shaft was probably cheaper than SS so boat builders went with what worked and cost the least. These days a bronze shaft will cost more than a SS shaft.
 
Jun 5, 2012
144
Catalina 30 mkI Victoria, British Columbia
Hi,
Have a look at my recent thread regarding changing the shaft coupler and at the same time going to a dripless PSS. If you are taking the shaft off to inspect, then doing so can often lead to needing a new shaft anyway (depending on if it needs to be cut and how much extra length you might have).
The coupler is the big deciding factor I bet! In my case the cutless was the only thing that DIDN'T need changing! :)
Also, MaineSail has some really great articles on his website that will no doubt be of use!
Cheerio.
 
Oct 17, 2011
2,808
Ericson 29 Southport..
As a mechanic, if I can get you to say: "yeah; better replace it all" - then I can just cut it all out and save myself a stack of tedious dis-asssembly work. Plus; I can then work with all new and nice parts and materials. I have to do less work, make some money on the new parts, and you pay the bill. And then have zero risk in warrantying the job. It's not so much trying to gouge the customer as it is eliminating work and gauging variables.

PHM
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These words are so true. When you take the number from the hill slowly extricating rusty corroded parts, more often than not the point of diminishing returns happen quickly. Unless you are doing this yourself, yes, just chuck it all probably. Another thing to consider, and I tell people this almost daily: While it's on the hill, fix ANYTHING below the waterline in question. A forty dollar cutlass bearing would be a no-brainer..
 
Feb 21, 2010
330
Beneteau 31 016 St-Lawrence river
Change the cutlass bearing

Hello to all of you,
I have owned several older boats and when cutlass bearing time came on one of them it was because the whole boat vibrated when decelerating under power! The bearing was really shot. But the shaft wasn't changed and lasted me another seven years and 2,000 hours of motoring! The new owner did a major refit but didn't change the shaft!
If your boat doesn't vibrate under power your shaft is more than likely true though it may be slightly worn and scored. A new bearing will adapt itself to a slight irregularity in the shaft in the same fashion as brake pads would adapt to slightly scored brake drums as long as they were round and not ovalized which would give you vibration.
If the bearing is on a strut it is relatively easy to change without pulling the shaft.
If the boat is wintered on the hard every year I would simply change the cutlass bearing and wait and see how the new one lasts... should it last five seasons or more keep it this way. If it is shot after one season you will know that the shaft is either shot or misaligned and you will then have to attack the big job.
This should be a winter project with final installation in the spring; not a last minute decision with some parts missing etc..
Good winds
Pierre