Is this an usual skeg/rudder cup design?

[Grassman]

Yesterday we went over an unknown underwater object. The impact was such that it jerked the tiller arm right out of my hand. After that the tiller was quite loose but steered okay. The rudder was still in the cup and the play was minimal, except for  an occasional 'clank', usually on revs higher than tickover, and the tiller arm would wobble and then settle again.

 

It became steadily worse so I called out RCR. Their chap donned his dry suit and went in for a feel. His prognosis was that the cup on the skeg had cracket and split in half. so I've now got to find somewhere to get the boat out of the water to take a proper look and repair. To me it looks like it's a very unusual set up the way the bracket and cup appears to have been attached to the end of the skeg rather than welded onto it, and I was wondering what you others think. Whatever I went over has probably struck the rear of the cup bracket which as you will see in the photo is the weakest point.

 

To me it looks a poor job which surprises me considering it's a Colecraft (built in 1995), and my highly reputable surveyor didn't comment on it when I bought the boat in 2012.

 

Your thoughts would be appreciated please.

 

 

 

 

 

[Jen-in-Wellies]

That is an actual proper bearing, rather than the crude cup that most narrowboat rudder pivots rest in. Should be relatively easy to replace. Undo, or crop the two bolts holding it on and take the old one to your friendly local bearing merchant for a replacement. If it is the right sort of bearing, one designed for a constant end thrust, while  continuously immersed in a water like substance, I don't know. As it survived many years without trouble till it got an external insult, it suggests the bearing design is fine. There are a lot of different sorts of 2 bolt bearings. First result from a search.

Edited June 10, 2022 by Jen-in-Wellies

[David Mack]

It looks rather odd that the thick steel skeg ends directly under the rudder shaft, with a much thinner extension added to support the back half of the bearing. I suspect this is a modification from the original arrangement. 

I can't see an ordinary bearing lasting well under permanent immersion in such a vulnerable location. I might be minded to remove the bearing and thin skeg extension, and get a more substantial extension and conventional cup (i.e. short length of 2" or so tube) welded on.

[Tracy D'arth]

Your rubber baffle in the rudder tube has dropped out too.

 

You can buy these flanged bearings in stainless steel but they are very expensive relative to the steel version.  Easy to change as has been said. I would doubt it is designed to take end thrust, the end of the rudder shaft is probably just resting on the skeg.

[BEngo]

That is a reet  bodge, and I would bet Colecraft did not build it like that. Gritty muddy canal water will wreck any sort of ball bearing in short order.

 

Ditch the fancy bearing and get the skeg extended to support a normal cup.

 

The rubber disc is fine- the water flow will push it up against the tube when needed.

N

 

[Tony Brooks]

4 minutes ago, Tracy D'arth said:

Your rubber baffle in the rudder tube has dropped out too.

 

You can buy these flanged bearings in stainless steel but they are very expensive relative to the steel version.  Easy to change as has been said. I would doubt it is designed to take end thrust, the end of the rudder shaft is probably just resting on the skeg.

 

If so put a copper or brass washer between skeg and stock to act as a bearing.

[David Mack]

20 minutes ago, Tony Brooks said:

 

If so put a copper or brass washer between skeg and stock to act as a bearing.

Available from most local shops at a very affordable price.

Edited June 10, 2022 by David Mack

[Jen-in-Wellies]

7 minutes ago, David Mack said:

Available from most local shops at a very affordable price.

The old style 2p's were a copper based alloy and so ideal. The newer ones are an iron based alloy and not so suitable. See if your 2p can't be picked up by a magnet to find a copper alloy one. All the current tails design ones are iron based. Only the older Welsh fleur de lys ones are copper. Newer ones are iron.

Edited June 10, 2022 by Jen-in-Wellies

[BEngo]

Neither copper nor brass are really ideal.  They are softer than the steel stock and skeg, so that the grit in the water will become embedded in the softer metal and will then wear the stock and/or skeg.

 

The best easy thing to do is to put a hardened ball bearing in a counter sunk hole in the stock or skeg.  The grit in the water then embeds itself in the soft steel, and will wear  away the easily replaceable ball bearing.

 

I know it is counter intuitive that the soft metal wears away the harder, but (if assisted by gritty muddy water,) it does and there are plenty of engineering text books which address it.  Think of a crankshaft, where the wear occurs on the crank pins, not on the soft white metal bearings.

 

N

[Tracy D'arth]

2 minutes ago, BEngo said:

Neither copper nor brass are really ideal.  They are softer than the steel stock and skeg, so that the grit in the water will become embedded in the softer metal and will then wear the stock and/or skeg.

 

The best easy thing to do is to put a hardened ball bearing in a counter sunk hole in the stock or skeg.  The grit in the water then embeds itself in the soft steel, and will wear  away the easily replaceable ball bearing.

 

I know it is counter intuitive that the soft metal wears away the harder, but (if assisted by gritty muddy water,) it does and there are plenty of engineering text books which address it.  Think of a crankshaft, where the wear occurs on the crank pins, not on the soft white metal bearings.

 

N

Good plot.

 

I build them upside down so the grit washes out. Currently the oldest one I built this way has lasted 23 years with no play apparent.

[Bod]

 

This is my 1998 Colecraft, earlier in the year, after the cup was replaced like for like.

 

Bod.

[ditchcrawler]

7 hours ago, David Mack said:

Available from most local shops at a very affordable price.

I thought they were made of steel now, copper being too expensive 

[Mike Adams]

It is better to take the downward force on the top bearing which is accessible for greasing and just let the bottom bearing act as a sleeve. I have seen ball, taper roller and plain bearings work well.

[ditchcrawler]

2 hours ago, Mike Adams said:

It is better to take the downward force on the top bearing which is accessible for greasing and just let the bottom bearing act as a sleeve. I have seen ball, taper roller and plain bearings work well.

My boat originally had a bronze bush set into the steel cup.

 

[john.k]

I would imagine the pillow block from bearing service would be quite unsuitable.....as mentioned ,steel ball bearings dont run in water for very long before failure,and the cast iron housing doesnt have much strength either.....the one pictured welded to a keel extension with a plastic water lube bearing would be a lot more resistant to damage from a knock.

[Grassman]

Thanks to you all for your feedback. I’ve arranged to have it dry docked next week which will reveal exactly what has become of it, and will report back. As for the rather bizarre design I will see if they can either replace the skeg with a longer one, or properly extend it, but because they are ‘fitting me in’ I doubt they will have time so it may have to wait until the next blacking in 2 years time.

 

For the moment I’d be fine just having a like for like jobby done so I can get moving again.

[ditchcrawler]

3 hours ago, Grassman said:

Thanks to you all for your feedback. I’ve arranged to have it dry docked next week which will reveal exactly what has become of it, and will report back. As for the rather bizarre design I will see if they can either replace the skeg with a longer one, or properly extend it, but because they are ‘fitting me in’ I doubt they will have time so it may have to wait until the next blacking in 2 years time.

 

For the moment I’d be fine just having a like for like jobby done so I can get moving again.

I would suggest in that case you warn them of what you have got, they may be expecting a standard cup arrangement

[PeterScott]

On 10/06/2022 at 10:47, David Mack said:

Available from most local shops at a very affordable price.

and protected from defacement by Section 10 of the Coinage Act 1971

[Tracy D'arth]

Just now, PeterScott said:

and protected from defacement by Section 10 of the Coinage Act 1971

Use an old halfpenny, no longer legal currency so exempt from the Coinage act I believe.

[ditchcrawler]

30 minutes ago, Tracy D'arth said:

Use an old halfpenny, no longer legal currency so exempt from the Coinage act I believe.

And better material

[David Mack]

55 minutes ago, PeterScott said:

and protected from defacement by Section 10 of the Coinage Act 1971

What about all those penny squashing machines?

55 minutes ago, Tracy D'arth said:

Use an old halfpenny, no longer legal currency so exempt from the Coinage act I believe.

The Act applies to coinage which was legal tender on 16 May 1969, even if it ceased to be later. So pre-decimal coins are included.

[Tracy D'arth]

7 minutes ago, David Mack said:

What about all those penny squashing machines?

The Act applies to coinage which was legal tender on 16 May 1969, even if it ceased to be later. So pre-decimal coins are included.

Oh, didn't know that.  I will be thrown into the tower!

I know an engineer who bores holes in coins to use as washers, he reckons its cheaper than buying them. 

Foreign coins?

[ditchcrawler]

As an apprentice we use to solder an old penny on top of the tube in electric Undercounter water heaters after we had ripped them to bits to descale them. A perfect fit

[magnetman]

I seem to recall that pennies also weigh an 1/8th of an ounce. 

 

I suppose these days street deals are done in grams. 

 

The joys of being old

Edited June 12, 2022 by magnetman
Typo and correction of obscure reference to something unusual

[Tracy D'arth]

We used old pennies to blank off the back boiler connections on direct water cylinders, a perfect fit in 1" union nuts.