Cutlass bearing or something else?

[wpc691]

Wanted to take the Admiral out for an instructional cruise with the new AIS. Got 100 yds from the dock when we heard a loud squawking noise for a few seconds from the back of the boat. I first thought it was somebody putting down a lift - it sounded just like it. We went another 50 yds and heard it again. The Admiral took the helm and I jumped down in the engine room, heard the squawk again just as I lifted the hatch. Saw the shroud on the stuffing box on the port shaft pulsing up and down about 3/16” and the stuffing box leaking about 3 drops a second. Shut that engine down, and returned to the dock. Went back to the engine room, nothing seemed amiss except the stuffing box leaking a drop every 2 seconds. I backed the stuffing box off, then retightened (probably tighter than usual), slowing the leak to a drop a minute. Today, my diver went under the boat...I was thinking he might find a palm frond wrapped up in the shaft...but didn’t. Said the wheel, shaft and struts looked fine. Rotated both wheels, said the port was harder to turn than starboard...maybe that’s an over-tightened stuffing box. No runout that he could see in the shaft. I went down in the engine room while he rotated the shaft, and didn’t see or hear anything unusual. I tried to wiggle the shaft and couldn’t. I’ve read quite a few threads here about bad cutlass bearings, but I don’t recall any reports of loud howling noises or shaft wobble. It almost seems like that kind of motion in the shaft would have to come from the transmission end. The boat was running perfectly right up to the moment it started squawking - no noises, no vibration, although we were at idle, so maybe not surprising. Any thoughts? I’ll be back in the engine room tomorrow with a pry bar to see if I can get something to wiggle. Anything else I should look for or try? Should I just head for haulout before something really breaks?

 

[SEVEN]

I just heard a high pitch went I went into gear, only at low RPM and only on the outside of the boat. I am going to haul out and have the bearings checked. Let me know what you find out.

 

[wpc691]

I just heard a high pitch went I went into gear, only at low RPM and only on the outside of the boat. I am going to haul out and have the bearings checked. Let me know what you find out.

Will do. This noise was REALLY loud. A woman crossing in front of me in a Sea Ray almost drove into the mangroves - I guess she thought I was blasting her with my emergency horn.

 

[SEVEN]

Totally different than mine. It was a very high pitch and only for a couple of seconds when I put her into gear.

 

[Scarlett]

Had that happen once on a boat and it turned out to be the rubber in the cutlass bearing had come loose and had folded over so it was actually jamming the shat in the bearing, like you said making the shaft very hard to turn by hand. Cure was obviously to replace with a new bearing. Seemed like a pretty weird thing to me but it happened. John

 

[Byresch]

I had one go out but the sound was a loud squeal. You could hear it all over the boat. People on other boats look over at us to see what was happening. Mine was the port side, replaced both to be on the safe side.

 

[wpc691]

Thanks guys, sounds like I’m in the market for new cutlass bearings. I did loosen up the stuffing box and verify that the shaft in question is much more difficult to turn. The amount of deflection I observed in the shaft while running is still pretty surprising. If it happened to be at a resonant frequency, I guess I should count myself lucky the shaft didn’t snap; maybe I’ll have it Magnafluxed while it’s out.

 

[Pascal]

Thanks guys, sounds like I’m in the market for new cutlass bearings. I did loosen up the stuffing box and verify that the shaft in question is much more difficult to turn. The amount of deflection I observed in the shaft while running is still pretty surprising. If it happened to be at a resonant frequency, I guess I should count myself lucky the shaft didn’t snap; maybe I’ll have it Magnafluxed while it’s out.

Since you re going to pull the shaft then absolutely get it magnafluxed. Personally having suffered a shaft failure once, I will have them magnafluxed every time they come off whatever the reason and every 5 to 6 years regardless.

 

[oscarvan]

Since you re going to pull the shaft then absolutely get it magnafluxed. Personally having suffered a shaft failure once, I will have them magnafluxed every time they come off whatever the reason and every 5 to 6 years regardless.

Out of curiosity what's a ballpark figure for that? Thanks.

 

[Pascal]

Not sure... I don’t think it was billed separately. Whatever the chemicals costs which is nothing compared to a new wheel!

 

[Colwyn D]

For clarity. Are the shafts ferrous and therefore capable of magnetic particle inspection, magnafluxed. I would have thought dye penetrant testing would be a suitable test for the likely defects.

 

[wpc691]

For clarity. Are the shafts ferrous and therefore capable of magnetic particle inspection, magnafluxed. I would have thought dye penetrant testing would be a suitable test for the likely defects.

Shafts are ferrous, so mag particle OK. Dye penetrant vs mag particle is kind of a “best anchor” subject. Mag particle is less fussy about part cleaning and surface irregularities. It will find near sub-surface defects, although I don’t think that would be meaningful in this case. It’s typically a faster test than dye penetrant. I’ve never procured a one piece mag particle inspection, so not sure about the cost - if it was a couple of hundred bucks, I’d be pretty happy. Big yards that do a lot of shaft and wheel work probably have sources; if not, I’d look for an automotive machine shop that does crankshafts, probably the lowest cost.

 

[Dan Mapes]

We had a similar boat. An 85 with detroits. We did the bearings but not because of noise. We were doing the seals and tuning the props and went for them since the rubber was peeling from the bronze.
I don't think our boats were high strung enough to warrant all of the extra exams. Larger yachts that run on plane with large diameter shafts sure.

But I wonder about the value added by extra exams at this size. I think a good visual will probably suffice. We had 1 3/4s in Freedom.

 

[wpc691]

We had a similar boat. An 85 with detroits. We did the bearings but not because of noise. We were doing the seals and tuning the props and went for them since the rubber was peeling from the bronze.
I don't think our boats were high strung enough to warrant all of the extra exams. Larger yachts that run on plane with large diameter shafts sure.

But I wonder about the value added by extra exams at this size. I think a good visual will probably suffice. We had 1 3/4s in Freedom.

Good point Dan. I’m usually moving just fast enough to get out of my own way, not much power through the shaft. My only concern is the “high” displacement oscillation the shaft saw, very different from normal operation.

 

[Pascal]

On my only experience with cracked shafts, nothing was visible with the naked eye until they were magnafluxed or whatever die was used. That was a 3 1/2 “ AQ22HS on a planning boat used probably 50% of the time planning

 

[krush]

Dye-pen is cheap and you can do it yourself.

 

[Colwyn D]

Dye-pen is cheap and you can do it yourself.

Where I was going Krush. Spent most of my life inspecting stuff and most on this forum I imagine can buy an aerosol can each of dye and developer and do their own shafts.
Clean the area, spray on dye, wipe off and spray on developer. Look for pink lines, cracks. If any get professional advice.

 

[dsharp]

if the shaft is occilating it's usually an engine alignment issue. Did the squeal go away when you idled it up while in gear? Can you tie the boat off at the dock and put the boat in gear and try to locate the noise?

 

[wpc691]

if the shaft is occilating it's usually an engine alignment issue. Did the squeal go away when you idled it up while in gear? Can you tie the boat off at the dock and put the boat in gear and try to locate the noise?

Yes, putting it in gear at the dock is my next step. If that shows nothing, I’ll repack the stuffing box and assess shaft rotation. I did note that the keyway on the shaft is 1/2” out of the coupling and the key right at the end of the slot. On the other shaft, the keyway is inside the coupling, and the key 3/4” inside the coupling. But, there is paint overspray on the shaft that makes it appear it has always been this way, as odd as it seems.

 

[dsharp]

Sometimes the keys will be loose enough to slide up and down the coupling’s keyway. The main thing that you want to check is where the shaft is running in the shaft log. The engine will usually settle on the reduction gear end causing the shaft to rub on the bottom of the shaft log. Not sure if your diver was able to check that with the boat in the water. If you have the coupling in-bolted you can pull up on the shaft to try to tell were the shaft is running in the log. Much easier to check when the boat is hauled out but, I don’t know what the capabilities are where the boat is located. Once you get above an 1 1/2 shaft it’s pretty hard to get the shaft to move much with the weight of the shaft and the thickness of the hose on the shaft log.