Checking shaft alignment

[High Current]

I recently acquired a 1990 Catalina 34 at auction and am in the process of getting her ready for launch. I managed to get the engine running (M25XP), but there was a lot of vibration. I then discovered that one of the motor mount nuts (port aft) had worked itself loose. Tightening this nut helped with the shakes, but I'm guessing that the prop shaft is probably out of alignment.

Sounds like a fun adventure except...my coupling flange looks like :

Universal recommends <0.001" per inch of coupling diameter (4"); even with some heavy wire brushing I can't imagine getting the outer surface that smooth. I'm not sure what to expect on the mated faces.

I've never done this before and I have and have questions/concerns:
- Is it worth trying to clean up the coupler, or just start over?
- Is it a foregone conclusion that I'll need a hack saw to get this coupling off the (bronze) shaft?
- For radial alignment, I didn't see an obvious mechanism to move the engine side to side. But it also seems as if the shaft just needs to be reasonably centered in the log. Am I missing something?
- Is there anything special I need to do to ensure the shaft is properly aligned with the cutlass bearing?
- When doing final check in the water, does the stuffing box support the shaft? Or do I leave the flange bolts most of the way in? Or...?

 

[Ralph Johnstone]

For radial alignment, I didn't see an obvious mechanism to move the engine side to side. But it also seems as if the shaft just needs to be reasonably centered in the log.

Radial ⇩ ⇨ ⇧ ⇦ should be reasonably close to the resting and undisturbed prop shaft. Angular alignment is the important measurement as stated by Universal :

Universal recommends <0.001" per inch of coupling diameter (4");

This is the procedure I found years ago. I've trimmed it way back since the first alignment after I proved the prop shaft wasn't bent and the coupling on the prop shaft was exactly 90 deg. to the prop shaft.

Your decision, but I'd rather have an SS shaft and clean flanges. Much nicer to work with and you're about to learn a whole new language. Keep the kids well away (for your safety) when you're working on this.

MOM ............................ what does #$%@^! mean ?

 

[BigEasy]

I recently acquired a 1990 Catalina 34 at auction and am in the process of getting her ready for launch.
I've never done this before and I have and have questions/concerns:
- Is it worth trying to clean up the coupler, or just start over?
- Is it a foregone conclusion that I'll need a hack saw to get this coupling off the (bronze) shaft?

Based on your photos, I would start over with new coupling , shaft, packing gland (at minimum, new hose & clamps). May as well replace cutlass bearing also. Re-eval engine mounts when you are putting everything together again.

 

[Hayden Watson]

• More than likely the mating surfaces are ok.
• It will not cost you more than time to see how it looks with some wire brushing.
• I was unable to remove the flange from my bronze shaft by any means other than an angle grinder. Once off, the shaft was out of spec for straightness so now I have a nice shiny SS shaft with a split coupling.
• The motor mounts have slotted holes in the base that allows them to move sideways a bit in each direction.
• The cutlass bearing will allow the shaft to sag a bit if the hose is still in good shape. My hose was rock hard so I replaced it with a proper 6-ply Buck Algonquin shaft log which while thicker was more flexible than the old. I then found the extremes of vertical and horizontal movement and shimmed it to the center of that range to do my axial alignment.
• You are correct that the final check must be in the water. Just leave the bolts in place and loosen them enough to get a small gap all the way around. Check the gap and all four sides and compare the differences of opposing sided. Say you have 10-thou on one side and 15-thou on the other your alignment is out by 5-thou. Rotate the shaft and remeasure to make sure you do not have a bend or unfaced coupling.

 

[Stu Jackson]

Congratulations on a fine boat.

We have tons of C34-specific info on our Catalina34 International Association forum and website:

Main Message Board

Discussion of all matters of interest to Catalina 34 sailors

c34.org

Tech Wiki – Catalina 34 International Association

Diesel Engine - c34.org

c34.org

 

[High Current]

Thanks everyone! Sounds like step 1 is to try to clean it up a bit then bite the bullet and separate from the transmission to see how feasible proper alignment will be post-launch. Unless things are unusable I don’t think a full shaft replacement is in the cards pre-launch (gotta be out of the yard in a couple of weeks) but definitely on the table for next fall. I have some electrification plans that will likely require it then anyway; best to do it only once.

@Stu - thanks, I already joined your wonderful organization and checked there first. Ultimately I figured this was more of a general question than C34-specific.

 

[jssailem]

I think you are heading in a good direction.
I did not like the condition of the shaft and stuffing box (corrosion). It is not what is obvious it is what you do not see.
I just replaced my shaft, coupling, stuffing box with a Dripless Shaft Seal. In my case all of that is under the engine so with the engine out for a rebuild all was exposed. At first I thought I could just reinstall the engine. The cursory exam of the shaft all looked ok. But... when I got the stuffing box open and started to replace the stuffing I discovered corrosion inside the stuffing box. This meant the shaft was at risk. So to be safe, I pulled it all out and replaced. Sure glad I did.

Look for corrosion in places you don't want to. That is where it hides.
I posted some images on the engine rebuild post.
A story of the engine that could.... Then didn't