shaft noise

[charlesson]

Last night after a rigorous WEd. night race, I noticed some metalic noise coming from the shaft or possibly the prop?. During the race, the transmission was in neutral and I could hear the prop rotating with a bit of vibration when we were close to hull speed.I think this is normal. Typically, there is no noise at lower speeds, however.Last night this metallic noise was constant at low hull speeds when the trans was in neutral.
Other than having sailed the boat "hard" during the race the only other variable I can think of is that I tightened my port shrouds prior to the race.Shaft coupling allignment issue? doubt it but maybe.

I will check the stuffing box. The cutlass bearing is only one season old. I have had a bit of shaft vibration at low RPM while in gear and under power but the noise last night is different. Sounds like metal on metal contact. Any ideas would be greatly appreciated.

Thanks in advance.

Ken Heyman
c34
"Wholesailor"
Chicago, IL

[John Langford]

What about a loose zinc banging against the cutless bearing as the shaft turned?

[Ray & Sandy Erps]

There was some discussion a while back ago about the warning tag on our transmissions that says our transmissions should be locked into reverse to prevent the transmission from turning while the boat is being sailed.  I don't recollect the reason for this, but figure that when the transmission is being driven by the engine, the plantary gear set spins in such a manner as to provide lubrication to the rest of the transmission.  With the engine off and the output shaft spinning, I suspect the rear output bearing isn't getting lubricated.  A good way to chase down the noise is to use a long handled screw driver as a stethascope.  Next time you hear the noise, place the bladed end the the screw driver on metal near the suspected source and hold the end of the handle against your ear.  The noise conducts very well through the screw driver and you'll be able to narrow it down to the source.  I've used this technique often on engines.  Good luck.

[Stu Jackson]

Ray

The outcome of that discussion about tranmission position (it rhymes!) can be found at:

http://c34.org/faq-pages/faq-transmission-position-sailing.html

Stu

[PAUL T.]

Ken.... If you have a PSS dripless shaft seal it can clank a bit when sailing in neutral. My shaft seal bounces around a little even though the shaft is true....... PAUL

[Ray & Sandy Erps]

Regarding strange noises from the PSS dripless shaft seal, I was given a scare a couple of times from a strange terrible sound that would occur occasionally from the drive shaft.  The first time I heard it, shortly after we bought the boat, I cut power immediately and put it in neutral, thinking I caught a line or something and was burning up my cutlass bearing.  The noise was come and go momentarily until I burped the shaft seal.  That seemed to take care of it until the next time I would dive on the boat and scrub the bottom, then the problem would flare up again.  After a considerable amount of investigation, I figured that exhaled bubbles were causing an air pocket in the drive shaft pocket, allowing the pss shaft seal to heat up or something.  Anyway, I'm careful to burp the seal after each bottom cleaning and/or haul out and haven't experience the problem since.  

Just some trival information in case someone else is tracking down some funny shaft noises with a dripless seal.

Ray

[John Langford]

If you occasionally get what the manufacturer calls "chatter" (but sounds a lot louder) from your PSS shaft seal it is probably from a bit of sand or weed getting between the carbon and ss plates. The chatter usually lets in a little water and solves the problem. If the problem persists then run a piece of 600 grit w/d sandpaper between the two plates. This also lets in a little water. If it still persists then you probably need to push the ss plate back about an 1/8" at a time until the phenomenon disappears. Over time the bellows get a little tired so that they lose tension and need to be retensioned.

Cheers
John

[Mike Smith]

My money says it's a loose zinc.

Mike