Grinding noise from shaft

[Ken13559]

I've had this for some years now. After couple of days of not spindling the prop, I get this grinding noise whenever I run and engage in Fwd or Rev gear. Grinding noise will go away after 10mins of Fwd. Then I've to engage to Rev and it goes away after about 10mins. Clearing the noise in Fwd spin will not clears it for Rev and vice-versa. Thereafter no more grinding noise (or very very much lesser) for next coupling of days. Looks like MTBN (mean time between noise) is about 5-6 days. So is it barnacles on shaft or in Cutlass? Last I checked, Cutlass has little play so no problem there. Gearbox oil looks goldenly good & at correct level ...as always. During several hours of motoring, there's no sign of anything untoward with the gearbox or shaft. I've Yanmar 2GM20F with Kanzaki KM2P-1 gearbox driving a Kiwi Prop. Noise happen with whatever prop I used.
Appreciate advise and insight. Thank you.

 

[RichH]

Use to happen to me on the Chesapeake Bay, with a fin keel and prop-strut configuration. Small fast growing mollusks (barnacles) would grow INSIDE the stern tube aperture in the hull .... and the rotating shaft would 'grind them free'. Painting the shafting and inside the stern tube with bottom paint very few years solved my problem. One season the teeny hard shells attached 'mostly' on the shaft ... and wore the fiberglass stern tube almost through due to the shaft attached 'barnacles' rotating inside the stern tube. If this is your problem, bottom paint is your friend, pulling the shaft out occasionally wont be.

Id expect Great Lakes sailors to have the same problem with the zillions of teeny Zebra Muscles.

 

[Chris Patterson]

This might not have anything to do with another thread on here very recently concerning whether the shaft should, or should not be locked while sailing does it?
As I recollect, the shaft is supposed to free-wheel on those Kanzaki's.

(Don't take MY word for it though).

 

[Ken13559]

This might not have anything to do with another thread on here very recently concerning whether the shaft should, or should not be locked while sailing does it?
As I recollect, the shaft is supposed to free-wheel on those Kanzaki's.

(Don't take MY word for it though).

Not about that. Anyway when I have the CSP on, I left it free turning. With FoF and Kiwi prop, not anymore.

 

[Ken13559]

Rich, ok will kiv on painting the shaft-log side in next haulout. My shaft log is bronze so I guess I shouldn't be too worry grinding the barnacles. ...right?

 

[Ken13559]

Archie, ?? what you're referring to?

 

[zeehag]

even bronze gets barnies--ask me how i know this....i also get salt build up in my shaft log--keeps the ingress of water to a minimum, but is still more than usual...makes a grinding noise when i initiate movement forward and reverse....

 

[Rick]

It seems that you talked yourself into what you think the problem is. However, there are some other options that could be in play.

When sailing with the engine in neutral, have you gone down below to see is your shaft actually spinning? Any grinding without the engine running?

You said your stuffing box is bronze. When is the last time you adjusted it? Have you put a temp gun on it to see is it hot underway? (It should run a little warmer than the temperature of your seawater). Felt it with your hand? Does it drip when under motor? When you are under sail if you put your hand on it, do you feel anything odd? Grinding?

When you check the oil in the tranny do you look very closely at it? Even take a paper towel, wind it up tight and dip it to check for any metal?

Barnicles perhaps, but a "grinding" noise that goes away could be alot of things that fix themselves when they come up to temperature.

Good luck

Really hope it is just sea critters since you said it has been going along for a while.

 

[RichH]

Rich, ok will kiv on painting the shaft-log side in next haulout. My shaft log is bronze so I guess I shouldn't be too worry grinding the barnacles. ...right?

NO.
On the boat which I had this problem ... bronze shaft log, bronze shaft. If ... this is the problem, you'll see the 'scaring', etc. as soon as you slide the shaft back, and hopefully no scaring in the FRG.

 

[Ken Palmer]

Something similar happened to me a few years ago on my Hunter 33.5. Turned out that the zinc clamped onto the shaft had loosened up, causing it to slip down towards the prop, and rubbing on the strut with the engine in gear. Cheap fix thank goodness.