Singing rudder

[MtB]

Hi everyone,

 

The rudder/tiller on our boat has always emitted a loud screech/singing/resonating noise as one swings it firmly from one side to the other when manoeuvring the boat. I've spent many a happy hour trying to fix it by introducing some lubricant to the top bearing without success. However, the boat is out of the water now (for blacking) and the noise is even louder. It clearly comes from the cup bearing at the bottom, that supports the weight of the rudder.

 

It's a plain steel cup welded onto the skeg with the vertical rudder shaft resting in it. The internal cup diameter is about 2" and the rudder shaft 1½". I lifted the rudder out, filled the cup bearing with waterproof stern gland grease (isn't all grease 'waterproof'?), put the rudder back in and the problem seemed to be solved. Now the chap doing the blacking has just told me the noise has returned.

 

The cup bearing is hemispherical but the end of the rudder shaft is cut off square, and a chamfer of about ¼" has worn on it. Might this be the problem? Do I need to do some handy work with the angle grinder to round it off to match the cup shape? Any other suggestions to fix it, anyone? The boat goes back in the water soon so I only have very limited time to fix it now. Rough and ready solutions are my only option, otherwise I'll have to live with it for another two or three years until next time it comes out.

 

All advice most welcome.

 

Cheers, Mike

[Yamanx]

Would a big phospher bronze washer fit on the end of the shaft, sit between cup and shoulder, say about 6mm thick?

 

Might be able to help if you need one.

 

Might be an option? Grease wouldnt last too long anyway I suspect.

[MtB]

Would a big phospher bronze washer fit on the end of the shaft, sit between cup and shoulder, say about 6mm thick?

 

Might be able to help if you need one.

 

Might be an option? Grease wouldnt last too long anyway I suspect.

 

 

Hi Yanmax,

 

That sounds like a brilliant idea. What did you have in mind when you said you might be able to help?

 

Are you local to me? I'm in Reading, Berkshire. Maybe I can get one locally. What sort of supplier stocks 1½" phospher-bronze washers? General engineering supplies like Tunes Engineering at Slough?

 

I wasn't sure how long grease would last either, but turns out it lasts about 48 hours!

 

 

Cheers, Mike

Edited November 8, 2006 by mike bryant

[howardang]

Hi Yanmax,

 

That sounds like a brilliant idea. What did you have in mind when you said you might be able to help?

 

Are you local to me? I'm in Reading, Berkshire. Maybe I can get one locally. What sort of supplier stocks 1½" phospher-bronze washers? General engineering supplies like Tunes Engineering at Slough?

 

I wasn't sure how long grease would last either, but turns out it lasts about 48 hours!

Cheers, Mike

Or what about a couple of old pennies?

 

Howard Anguish

[Yamanx]

If you give me the sizes, o/d, i/d, and possible thickness I'll source one or get one made and post it to you. Phosphor bronze will still wear out without lubrication, but should last a long time. We also use some heavy (Very heavy) duty nylon stuff as well that might be better, it has an impregnated lubrication as will last easily as long if not longer. Whatever your preference.

[Yamanx]

I've just gone and had a look and I've got two.

 

They are 50mm (2") i/d x 70mm o/d (2 3/4") x 5mm thick

 

or more likely

 

40mm (1 1/2") i/d x 70mm o/d (2 3/4") x 3mm thick, which should do the job nicely.

 

PM me your address and I'll post it off today

[John Orentas]

Hi Mike.

 

Cup diameter of 2" and shaft dia of 1.5" sounds excessive, and I am sure this is the major cause of the problem. Yes try as Yammy suggests this time but plan for a new bottom bearing on the next occasion. Not a big job to cut off the old bearing and replace it with a pre-made one with a much tighter tolerance, 0.1" will be ample.

 

Steel / steel bearings do seem very crude but they do generally last the life of a boat and they are lubricated by the surrounding water, I suspect yours was over-bored from new.

[Geoff]

Mike,

 

Simple answer that I tried when my boat was last out of the water, have a look in your pocket for a 2p coin, and drop that in

Fits a treat !!

 

Just dont tell the Bank of England

Geoff

[Keeping Up]

Or what about a couple of old pennies?

 

Howard Anguish

Yes that worked on my old boat "Thistle" too.

Allan

[DHutch]

So you've got a 1½ square shaft steel, running in a 2" steel cup? Sounds Nice already!

- However, as has being mentioned, the main force will be downwards, due to the weight of the rudder. So sticking some sort of bush/bronze washer in there would be my suggestion too. Short of changing the whole lot.

- Also, as for the grease. Normal grease is emulsified with soap, which although behaves fairly water proof for a short time, will degrade and fail is submerged. Waterproof greases such as sterntubegland grease and designed to be fully waterproof however.

 

 

Daniel

[MtB]

If you give me the sizes, o/d, i/d, and possible thickness I'll source one or get one made and post it to you. Phosphor bronze will still wear out without lubrication, but should last a long time. We also use some heavy (Very heavy) duty nylon stuff as well that might be better, it has an impregnated lubrication as will last easily as long if not longer. Whatever your preference.

 

 

Hi again Yamanx,

 

Only just got in from work now and read your kind offer. Thank you.

 

I'll go down to the boat first thing tomorrow and take some proper measurements. I'm only going from memory that the cup is 2" internal dia. The shaft is amost certainly 1½" as it looks the same to my eye as the prop shaft, but the cup could be bigger, as there was at least a ¼" of space all around it, possible a good deal more. I can't remember exactly.

 

I may well be able to find some old pennies to drop in there as others have suggested, but the decimal currency 2p coin also suggested won't do really as it is copper-plated mild steel!

 

I should also get a clearer idea of when the boat is going back in so I'll know if there's time for you to post me one. Thanks again.

 

Cheers, Mike

 

 

P.S. I notice now that you are in Shropshire. Plumbers find reading quite difficult sometimes :-) I also notice I spelled your username wrong originally, DOH!

Edited November 8, 2006 by mike bryant

[scrumpylurcher]

Never had chance to try it but it was suggested by a surveyor that an old ball bearing dropped in the cup would cure both noise and stiffness always assuming that the top bush is free.

 

Scrumpy Lurcher

[DHutch]

...but 2p coin also suggested won't do really as it is copper-plated mild steel!

Ive you've ever tryed to cut one, i ashore theres nothing mild about the steel used to make 1/2p coins!

- However you are right, they havnt been bronze for a long time, except a few that they make in bronze around 1999 or somthing odd like that.

 

 

Daniel

[David Schweizer]

Ive you've ever tryed to cut one, i ashore theres nothing mild about the steel used to make 1/2p coins!

- However you are right, they havnt been bronze for a long time, except a few that they make in bronze around 1999 or somthing odd like that.

Daniel

In fairness Howard did say old Pennies, (which were extinct before you were born Dan) they are much larger than the modern penny and are made of bronze, or something akin to it. If you need any, I have boxes full of them.

Edited November 9, 2006 by David Schweizer

[John C]

I wonder if the problem is really in the socket supporting the the rudder, what type/condition is the other bearing in? If it is a ball bearing then there should be no discernable play in it.

 

Phosphour bronze and mild steel are incompatible as a bearing material, the out come will most likely be excessive wear.

 

You might try, while the boat is out the water, drilling a small hole (6mm) in the bottom of the socket to let the muck and c**p out of the bearing. I dont suppose it will stop it singing but good practice anyway.

[David Schweizer]

Phosphour bronze and mild steel are incompatible as a bearing material, the out come will most likely be excessive wear.

Back in the 1960's we got so fed up with having to repeatedly re-whitemetal the big ends on our Working Boat engine (a V4 Turner) that we re-metalled them with bronze. The problem disapeared and they were still fine when the engine was replaced about ten years later. Perhaos the permanent lubriction with oil makes a difference.

[MtB]

Never had chance to try it but it was suggested by a surveyor that an old ball bearing dropped in the cup would cure both noise and stiffness always assuming that the top bush is free.

 

Scrumpy Lurcher

 

 

That's a good idea and I can imagine it working very well.

 

Went back to the boat yesterday for a more careful look, and the description of the bearing I originally posted was wrong. The vertical rudder shaft is 1½" as I said. The cup bearing welded to the skeg is not hemispherical though, and it is not over-sized as I originally (mis)remembered.

 

The cup bearing is about 1" deep and the rudder shaft (is there a proper name for it?) fits it with about 1/16" clearance, so that matches properly after all.

 

The base of the bearing isn't hemispherical, it's a shallow cone shape. The sides of the cone slope down from the perimeter towards the lowest point in the centre at about 30 degrees from horizontal. The rudder shaft looks as though it was originally cut square and the cone shape of the cup bearing has worn a small 30 degree chamfer on it. This chamfer forms the bearing face and supports the weight of the rudder and tiller. I think the end of the rudder shaft should have been machined to a matching point-shape but nobody bothered. The builders weren't people with an eye for detail. The tiller must have been quite stiff when the boat was new.

 

Anyway, this leads back to the idea of putting a ball bearing into the cup. I think this would work very well as the cone shape would keep the ball in the centre, and the the weight of the rudder will taken in the centre of the rudder shaft, on the ball, instead of around its perimeter. This should cure the singing noise nicely. The reasonably close fit of the rudder shaft in the parallel section of the cup bearing will mean minimal side-to-side backlash in the bearing when steering.

 

I reckon the ball bearing needs to be 3/8" or 10mm, and will be a more elegant solution than a washer. Thanks Yamanx for your offer of making me a washer but I think I'll try the ball bearing first unless anyone here can convincingly argue that a phosphor-bronze washer would be better.

 

If I'm wrong, would it be feasible to expose the skeg again by resting it on the sill of a lock (and putting the washer in)? I'm sure BW would throw the book at me if I was caught, but is it truly risky or a viable technique?

 

Cheers, Mike

Edited November 10, 2006 by mike bryant

[John C]

Back in the 1960's we got so fed up with having to repeatedly re-whitemetal the big ends on our Working Boat engine (a V4 Turner) that we re-metalled them with bronze. The problem disapeared and they were still fine when the engine was replaced about ten years later. Perhaos the permanent lubriction with oil makes a difference.

 

This bronze wiould have been either a tin or lead bronze, phosphour bronzes are used in very few applications, when its needed and used correctly then nothing betters it. Incorrectly used, its nothing but trouble.

 

Incidentally, the modern trend with crankshaft bearings is to use aluminium based alloys for bearings

[MtB]

Update:

 

I put a 10mm ball bearing into the cup in the end, and the boat is now back in the water.

 

Took the boat back to our moorings at Burghfield on Saturday up the Kennet against the fiercest current I have ever experienced. Struggled to get through the final bridge upstream of the Oracle passage in Reading town centre due to sheer opposing current, then had to negotiate dozens of white-water canoeists at County Lock who seemed intent on ignoring our presence whilst playing in the violent weirstream around the lock entrance.

 

Not a squeak from the rudder though. Good solution (so far).

 

Thanks for all your input.

 

Cheers, Mike

[DHutch]

You appear to have found a solution then, good news indeed!

 

 

Daniel