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Tiller shake


MHS

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18 minutes ago, Slim said:

I experienced tiller shake for a number of years and tried to cure it without success. New flexible mounts, R & D coupling replaced with a Sigma Drive coupling, new bottom cup, new top bearing, prop balanced by Crowthers, apparent very very slight bow in rudder blade corrected and I'm sure several other things which slip my mind. Any number of people, expert and lay, gave their opinions but no one could cure the issue. Everyone agreed that there was very little if any wear in the stern tube/prop shaft. Over time the stern gland started to drip more and need more frequent repacking. Two years ago the leak increased rapidly and I aborted a local cruise. On the slip I stripped the stern gear down and found that the 1.5" prop shaft had worn down to under 1.2" in the area of the seal. Once out of the boat it was obvious that there was a fair amount of wear between the shaft  and the tube. This wear was not evident with the parts in situ. Since then (Sept 19) all my trips have been on the South Oxford (shallow) but so far as I can see the shake problem has been resolved. 

 

Should add that I've had the hull from new (self fitout) and that the stern gear and engine beds were installed by the builder (Eastward Engineering) before delivery.    

 

There should be no wear between the shaft and tube. At a guess, I would expect around 6mm clearance all round. There may be wear in the stern bearing or in the stuffing box area. With a reasonably adjusted stern gland it would be difficult to find wear around the stuffing box but it should have been easy to find wear at the prop end on a conventional narrowboat. Maybe harder if there is a trust bearing on the shaft in front of the stern gland like Aquadrives.  We could even detect the compression of rubber in Cutless bearings.

 

 

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8 hours ago, Tony Brooks said:

 

There should be no wear between the shaft and tube. At a guess, I would expect around 6mm clearance all round. There may be wear in the stern bearing or in the stuffing box area. With a reasonably adjusted stern gland it would be difficult to find wear around the stuffing box but it should have been easy to find wear at the prop end on a conventional narrowboat. Maybe harder if there is a trust bearing on the shaft in front of the stern gland like Aquadrives.  We could even detect the compression of rubber in Cutless bearings.

 

 

Tony, I'm having difficulty in understanding your first two sentences. To clarify my post , the .3" wear was in the area of the stuffing gland. There was little detectable wear at the prop end when the shaft was in situ but when the shaft/tube components were removed it was possible to 'rock' the two parts indicating (to me) wear.  All I know is that since replacement my tiller shake has disappeared. I offered my experience to the OP for him to make of it what he will.  

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3 minutes ago, Slim said:

Tony, I'm having difficulty in understanding your first two sentences. To clarify my post , the .3" wear was in the area of the stuffing gland. There was little detectable wear at the prop end when the shaft was in situ but when the shaft/tube components were removed it was possible to 'rock' the two parts indicating (to me) wear.  All I know is that since replacement my tiller shake has disappeared. I offered my experience to the OP for him to make of it what he will.  

 

First of all you said "Once out of the boat it was obvious that there was a fair amount of wear between the shaft  and the tube." Note the last word - tube. The tube itself should get nowhere near the shaft, so either you had a very odd setup that would be liable to seize or that sentence was just plain incorrect. Now you have in effect corrected it to say the wear was in the front bearing and gland area. That is understandable, wear between the shaft and bearing & packing. With the shaft reasonably well-adjusted, the packing would act as a bearing on an undersized shaft so that would make detecting any shaft/bearing wear difficult to impossible without unpacking the gland. Then add that many so-called flexible gearbox couplings are nothing of the sort so they also conspire to prevent you waving the shaft from side to side.

 

I was not questioning the fact removing the wear solved the rudder shake, but I was questioning the veracity of what you wrote re the wear and now you have been explicit as to where the wear was it can no longer divert or confuse people who may be reading this topic.

 

I have explained why you were not able to detect wear with the packing and shaft in situ. I think if anyone feels the need to do that they would be better to remove the packing and use a piece of stiff bent wire to feel along the surface of the shaft inside the stuffing box.

 

 

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Surprising how a shaft will wear. The stainless steel shaft on 'Bee' is secondhand from a boat jumble. Its long, maybe 6` or so, can't remember offhand, and I guess it was removed because of a worn area presumably from gland packing on its original boat. I took a chance on it fitting Bee and it does, the worn part is now inside the stern tube somewhere and the shaft runs on its unworn part. I guess it had worn a groove 1/8" deep.

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12 hours ago, ditchcrawler said:

If you want to see a worn shaft look in this blog photo http://narrowboater.blogspot.com/2020/10/banburyshire.html

sHAFT%2BIMMAGE.jpg

My immediate reaction to that photograph was that it was of my shaft. I've still got it somewhere and I'' dig it out and post a photo later.

13 hours ago, Tony Brooks said:

I have explained why you were not able to detect wear with the packing and shaft in situ. I think if anyone feels the need to do that they would be better to remove the packing and use a piece of stiff bent wire to feel along the surface of the shaft inside the stuffing box.

To clarify, the packing was removed several times over the years for inspection by several people (myself included) with various probes as well as mirrors and an endoscope.  

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