Acceptable prop shaft wear?

[RaymondR]

You can purchase thin SS sleeves, that slip over the shaft and are fixed with epoxy, which provide a new surface to seal against.

[Bowdrie]

Originally Posted by MicHughV

What I've done before is to cut a very thin slice off the arse end of the cutlass bearing, if you can get to it, after pulling the shaft....plus/minus 1/16-1/8", re-insert the shaft, and insert over the the shaft at the front end of the prop tube.
This way you'll know that shaft is centered in the tube and can align the engine flange and prop flange so that it is spot on.
After which, you remove the that sliver of cutlass bearing and replace the stuffing box, etc.

I've used a "similar but different" approach before.
Using a board with a V-notch cut in it to support the inboard end of the shaft.
You move the board up/down/left/right until you can "feel" where the shaft turns smooth/true without binding on the rubber in the Cutless.
Yes, it does take a bit of finesse and patience, (both are hallmarks of a good mechanic,) but it's surprisingly accurate.
it'll get you within a few thousands, (assuming the Cutless isn't worn,) then you can fuss with the engine mounts to bring all together.
As an aside; you don't clamp up the packing gland hose until the alignment is finished, you want the gland nut to have equal clearence around the shaft.

[MicHughV]

I learned shaft alignment the hard way.
On my first boat, the one I built, I did not understand the finer details of an engine install, and my shaft was not centered in the tube.
This resulted in wearing out the cutlass bearing in no time, and surprisingly, also wearing the s/s shaft down inside the cutlass bearing. You wouldn't think a rubber bearing can wear down a s/s shaft, but it can.

The wear was pretty bad in both bearing and shaft, and I had to replace both.
This where I used the trick outlined above to find that the shaft alignment inside the tube was severely off.

Finally got it right though. Took some time to re-align the engine, etc.

[David Mathis]

With the old style packing, you are likely to be successful by polishing the wear area then reinstalling it. The question is, why did it wear? Three most likely causes: packing nut too tight, grit in the packing, or misalignment. Replace the packing then check the alignment. Motor mounts are a good place to start checking but what appeared to be a minor strike could have slightly bent the strut to cause misalignment and the wear. Did you notice any uneven wear on the cutlass bearing?

[Cheechako]

With the motor out, I would get it replaced just because now is the time. Cant tell everything due to reflection, but there is some grooving.
If the shaft sticks out of the strut far enough to slide in further, cutting to change the wear area is a valid thought for a budget, especially on a daysailor.
But a traditional packing should work fine with the minor wear.

[OS2Dude]

As they say in Temporal Mechanics, 'There is no present like the time'.

Assuming the boat is on the hard, having the engine out is the best time to replace the shaft, hose and sleeve bearing. Our boat still had the OEM bronze shaft when we did a refit a few years back. It had sized to the coupler and would not budge. (Yes, we tried heat, penetrating oil, a gear puller, etc.) It is also an excellent time to replace the stuffing box hose and sleeve bearing. I feel her pain, but it is cheaper to do it now than redo half the effort again later. If that shaft is stuck in the coupler, having the engine out will be a Godsend as it will give the access needed to ease the trouble of getting it out. I believe a new shaft, coupler, and facing from Catalina Direct was about $750 USD at the time. Also check to see if the skeg is tight. Ours was loose and I had to grind away an inch or so of fiberglass to get to the nuts that were under the fuel tank...

If the surface of the shaft is SMOOTH and ROUND (or can be made so on a lathe) at the stuffing box location, a thicker packing material can take up some size differential. If it is out of round nothing will stop it from leaking and a rough surface will just eat the packing until it leaks. (Tightening the stuffing box too much in order to keep it from dripping at all will score the shaft. Stuffing boxes are supposed to drip a little while the shaft turns.)

The problem with cutting the shaft is there is a keyway machined into it that keeps the shaft from spinning inside the coupler along with 'dimples' for the two set screws that keep the shaft from falling out of the boat when it is motoring in reverse. If you cut this off, then a new one will need to be machined into the shaft and new dimples created.

Marine How To has a lot of articles for boat owners. One in particular you may want to read is https://marinehowto.com/a-new-prop-shaft/

[kayakerChuck]

As always, CF is a wealth of information.

The grooves are nice and round with no burrs or hard edges. I'll polish things up, replace the packing, and hope for the best. (If this were my boat, I'd replace the shaft while the motor is out, but she is willing to take the chance that this will work.)

Thanks for the tips on aligning the shaft, etc!

I'm 100% positive the current packing was tightened until it stopped leaking. I will point the owner at multiple resources that explain why it must drip a bit in use. Marine How To is always high on the reading list.

[OS2Dude]

At least replace the stuffing hose, especially if it is original. (Real stuffing hose, not sanitation or exhaust.) With the engine out even if the coupler is stuck you can remove the prop and pull the shaft into the boat. That would make replacing the sleeve bearing easy too.

You may want to try to loosen the couple while you can. If it comes free, great! Lube it and put it back in. If not, at least you'll know when the time comes.

[Newf1]

If you decide to replace the hose could you not lengthen or shorten the new hose length to move your packing off of the existing wear area? Any reason not to do this?

[Bowdrie]

Originally Posted by OS2Dude

Assuming the boat is on the hard, having the engine out is the best time to replace the shaft, hose and sleeve bearing. Our boat still had the OEM bronze shaft when we did a refit a few years back. It had sized to the coupler and would not budge. (Yes, we tried heat, penetrating oil, a gear puller, etc.) It is also an excellent time to replace the stuffing box hose and sleeve bearing.

Agree.
And while all is removed is a great time to drill/tap the stuffing box for a Zerk fitting just aft of where the packing bottoms-out.
When you can pump a shot of grease in there on occasion, you'll be surprised at how long the packing will last and how little it needs to be tightened to not leak.
Regarding couplers/keys; if you have to use a hammer to get them in they are way too tight, should be a "sliding" fit, needing but little effort/light tap.
When installing a coupler make sure the edges of the keyway on the shaft are not sharp, use a sharpening stone or a small/fine file to break the edges, leaving a little chamfer.
The same with the edges of the keyway in the coupler.
Also take the key and stone/file a small chamfer on all 4 edges of the sides and put a little bevel on the ends.
The same attention given to fitting key/keyway on shaft and prop also recommended.

[OS2Dude]

Originally Posted by Newf1

If you decide to replace the hose could you not lengthen or shorten the new hose length to move your packing off of the existing wear area? Any reason not to do this?

On the older 30s anyway, there is not a lot of 'wiggle room' involved. The hose is already about as far back as it can go due to the angle of the log to the hull.
You need room for four hose clamps (Two on the log, Two on the stuffing box) so you can't make it much shorter. Making the hose longer would push the stuffing box forward which may make adjusting/repacking it in the future difficult.

[Tanqueray]

I pulled my ~30 year old bronze shaft on my O’Day 322 when I saw what I thought to be circumferential cracks on the shaft. Once I removed it, there was wear at the stuffing box and at the cutlass bearing.

I decided it was ti e to replace it, and ordered a new SS shaft and a new coupling, and had it fitted.

The cracks concerned me more than the wear, but I was planning to go to a dripless shaft seal, so I wanted a nice smooth finish on the shaft.

Here is a short video on the shaft condition…

https://youtu.be/4RlzgOOXhhQ?si=s-POF7WhPpJdjVUb


Greg

[kayakerChuck]

I had my oscillating tool in my hand for other boat fun. It cut the old hose off in a few seconds. :-)

The owner is out of funds, so I'm just going to spiffy up the old shaft as well as I can.

Moving the packing to a different place on the shaft is a great idea. There is no room for a longer hose. Would it be OK to shorten the hose a bit- maybe 3/4"?

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The more I work on this boat, the more I'd like to have a beer with the designer... .

[Boatguy30]

Propeller shop in Bradenton FL makes those for Catalina.

Can't be much maybe $500. If it's salt water definitely do it. In fresh if it's not leaking much should be OK.

[sinnerman]

If I had the engine removed, I personally would have a new shaft made (and a matched coupling). But since the budget is blown, that is not an option.

Most important is that the shaft is smooth and not "out of round" at the packing seal area.

This touch-up is best done in a machine shop (on a lathe...) by a machinist.

I assume you will be replacing the stuffing box hose....

Clean up the threads on the stuffing box, and clean out the old packing. Lube the threads.

With the boat on the hard, the cutless bearing in the prop strut should be checked and replaced if worn (budget or not).

Check that the prop strut is not bent, loose or with severely cracked fiberglass around it. See pdf of strut installation

When the engine is reinstalled, as others stated it will need to be aligned.

This starts (again as others have stated) by centering the prop shaft in the tube which passes through the hull. ("shaft log"). With the shaft centered, the basic engine alignment is then performed.

The alignment should be performed by someone who knows what he is doing.

The final alignment is performed with the boat sitting in the water.

BTW , my boat is a 1984 Catalina 30 as well.

My two cents.

Cheers.