Rudderstock bearing question (as in does mine have one?)

[RS_Pete]

Looking for some advice regarding the rudder stock support / bearing on my narrowboat.

This has never felt smooth since we brought her and I felt I should investigate further.

The boat, or at least the rear was built sometime in the 60’s.

Looking at this it appears different from others I have seen that have a bearing block mounted on the rear supporting the top of the rudderstock.

I had thought originally that the “mushroom” cap was a simple pressed or spun steel cover for weatherproofing sitting over a bearing (and that may well be its purpose.)

However, this is a solid steel machined piece with a parallel steel section below it sitting in the top of the rudderstock tube.

The fit of the parallel section in the rudderstock tube is loose or sloppy, allowing movement at the tiller end radially in all directions of approximately 6mm

With a pry bar the whole lot can be lifted at least 25mm (1”) and the parallel bar slides up and down in the tube freely.  The tiller and rudderstock can be, with a pry bar again, be lifted through the mushroom and parallel section by a similar amount.

 

Can anyone throw any light on how this is supposed to work?

I am wary of trying to dismantle at present without a greater understanding as I am concerned as to how willing the parts will be to separate. I don’t want to end up in a situation where it can’t be reassembled easily… However, it will need addressing at some point in the not too distant future.

[BEngo]

The rams head sits over the rudder stock and is held in place by the bolt and washer.  There may, or not,  be a taper (round or rectangular) on the stock and a matching one in the rams head, or not.  Removing the bolt and washer will show.

 

All is otherwise as shown in your sketch.

 

The curved mushroom cap is the top of a hefty block of metal that sits in the rudder tube. There is a hole in the centre through which the stock passes.  That is the top bearing.  Because it is steel in steel there is usually a substantial clearance aka a rattling good fit.  If you can get it apart it is a good idea to fit a bronze bush into the mushroom. This can be a better fit on the rudder stock, especially if is fitted with a grease nipple

A

 

To dismantle: 

 

Fasten a rope to the rudder blade and the other end to a dolly/ answer pin so that  you can recover the rudder if things go wrong.

 

Belt a couple of wood folding  wedges in between the top of the blade and the counter to stop the stock rising and leaping out of the cup at the bottom

 

Remove 3/4 AF bolt and washer.

 

Lever the rams head off the rudder stock.  This is usually easier said than done.  Liberal applications of Plus Gas, diesel,  heat, violence and  ungentlemanly  language will probably be needed. You may even be able to get a puller on.  Don't drop the rams head in the water☹.

 

The mushroom should then just lift off the stock.

 

Reassemble with plenty of copper grease on the rams head to stock join. 

 

If the rams head really must come off but does not show any sign of moving  then, in extremis, split the collar that sits onto the stock using a 1mm cutting disc and force a steel wedge in.

 

Either weld the slot up before refitting or, better, get a pinch bolt or two fitted to tighten the collar onto the stock.

 

Have fun.

 

N

Edited February 15, 2022 by BEngo

[David Mack]

Looks like I your case the mushroom shaped piece is fixed to the rudder shaft, and rotates with it.  Normally it would just sit in the top of the rudder tube, and the rudder shaft would rotate within it. There should be a small gap between the bottom of the boss at the bottom of the swan neck and the top of the collar (or  'mushroom').

 

Recent similar thread:

 

 

Edited February 15, 2022 by David Mack