Swan Neck sheared off

[DaveP]

Classic error in Thornes Lock today. Too busy showing crew a handspike in the top gate to notice the boat had drifted rearwards far enough for the swans neck to become trapped under the bottom gate walkway and snap off. It did so after holding the rear down by about 8in which fortunately wasn't enough for any water ingress into the hull.

 

 

No amount of fishing with magnets found the arm; so it's down there somewhere. Trouble is, as it's a river lock there's about 10ft of depth as a minimum. Thanks must go to the boat who breasted us up and brought us safely back to the mooring.

 

So - the questions are; how do I get this assembly apart? What am I likely to find inside, and where can I source a replacement neck and bar?

 

Cheers,

 

Dave

[steven wilkinson]

 

I have often wondered why they are that shape? why not straight up?

[jelunga]

 

I have often wondered why they are that shape? why not straight up?

Mechanical advantage

[Timleech]

Something a bit funny about that picture. Certainly it doesn't appear to be one piece of steel which has sheared, more likely two pieces welded together and the weld has failed. Possibly.

 

Tim

[Bob-18]

Oooo burger :-(

[twbm]

Wild guess - does the stud clamp the collar on to the rudder post? If yes, then perhaps the rudder and post were fitted by being offered up through the counter then dropped into the skeg, then as has been inferred the swan neck welded on to it. The collar may well also have a sleeve to act as a top 'bearing' inside the tube through the counter.

[the grinch]

its likely the only way to get it apart is to grind off the damaged area on the top of the rudder post and then prise the collar off most likely just grease inside doubt there is a bearing inside but there maybe.

once you get the rudder out then you would be wise to replace it completely as trying to weld a new bit on top will leave a weak spot in the same area.

[RLWP]

Mechanical advantage

 

Where's that QI klaxon sound

 

Richard

 

Something a bit funny about that picture. Certainly it doesn't appear to be one piece of steel which has sheared, more likely two pieces welded together and the weld has failed. Possibly.

 

Tim

 

I agree, or it has cracked in the past and failed this time

 

Richard

[allybsc]

Classic error in Thornes Lock today. Too busy showing crew a handspike in the top gate to notice the boat had drifted rearwards far enough for the swans neck to become trapped under the bottom gate walkway and snap off. It did so after holding the rear down by about 8in which fortunately wasn't enough for any water ingress into the hull.

 

 

No amount of fishing with magnets found the arm; so it's down there somewhere. Trouble is, as it's a river lock there's about 10ft of depth as a minimum. Thanks must go to the boat who breasted us up and brought us safely back to the mooring.

 

So - the questions are; how do I get this assembly apart? What am I likely to find inside, and where can I source a replacement neck and bar?

 

Cheers,

 

Dave

 

 

OH Poo! You must have been cross, glad you had someone to help out.

[jelunga]

Where's that QI klaxon sound

 

Richard

 

 

 

I agree, or it has cracked in the past and failed this time

 

Richard

Go on then, why?

[Davidss]

That stud is actually a grease nipple on a tube extender, although judging by the paint over the nipple, and the dry rust where the rudder shaft comes through the collar, there has been no grease down there for a while.

I think the first step is to remove the paint completely, from all the circular bits, by sanding or chemical attack. Then you can see what other fixings might exist and proceed accordingly.

For instance, how is the the collar the nipple extension is screwed prevented from turning?

Is the bush welded to the deck a single tall bush, or a short bush with a spacer?

 

And what the hell is wrong with a bit of simple and obvious cleaning before posting pictures to ask questions?

Show some inclination to help yourself, don't just parasite on the back of others.

[MoominPapa]

And what the hell is wrong with a bit of simple and obvious cleaning before posting pictures to ask questions?

Show some inclination to help yourself, don't just parasite on the back of others.

That's a bit OTT. Removing all the paint from that is non-trivial and quite possibly not necessary. A reasonable possibility is that someone posts to the effect that "Yes, it's Dursley Widget Co collar, grub screws at 3 o'clock, and 9 o'clock then hit it once just HERE."

 

MP.

[steven wilkinson]

 

yes - go on then - mechanical advantage?

 

surely there is no difference at all if the distance between the end of the tiller and its centre of rotation is exactly the same?

[MartinClark]

 

yes - go on then - mechanical advantage?

 

surely there is no difference at all if the distance between the end of the tiller and its centre of rotation is exactly the same?

 

Oh, come on - if the tiller was not swan-neck shaped then there wouldn't be enough room to hang your mooring rope!

 

Edited May 6, 2012 by MartinClark

[RLWP]

Go on then, why?

 

The mechanical advantage of the tiller is determined by the distance from the steerer's hand to the centreline of the rudder shaft, measured perpendicular to that axis. So all the fancy, curvy stuff out the back makes no difference to the mechanical advantage. The tiller could be a vertical shaft with a right angle bend at the top and would work just as well for steering the boat.

 

I think (WARNING - ASSUMPTION) the rearward curve is to allow access to the top nut on the rudder shaft, plus tradition

 

Richard

[Timleech]

The mechanical advantage of the tiller is determined by the distance from the steerer's hand to the centreline of the rudder shaft, measured perpendicular to that axis. So all the fancy, curvy stuff out the back makes no difference to the mechanical advantage. The tiller could be a vertical shaft with a right angle bend at the top and would work just as well for steering the boat.

 

I think (WARNING - ASSUMPTION) the rearward curve is to allow access to the top nut on the rudder shaft, plus tradition

 

Richard

 

I'm not a theoretical mech eng, but I wonder whether the traditional shape will be stiffer, for a given size of bar, than a simple vertical shaft would be with a 90 degree bend at the top?

One reason for doing it the traditional way is that you can have a removable tiller which leaves a clear space that can extend behind the centre line of the rudder post.

 

Tim

[RLWP]

I'm not a theoretical mech eng, but I wonder whether the traditional shape will be stiffer, for a given size of bar, than a simple vertical shaft would be with a 90 degree bend at the top?

One reason for doing it the traditional way is that you can have a removable tiller which leaves a clear space that can extend behind the centre line of the rudder post.

 

Tim

 

I think it is actually the other way around, there is more 'spring' in the traditional one, making it less vulnerable on the cut

 

However, I think you have nailed it about the removable tiller. It makes it much easier to get out of the back cabin when the tiller is removed

 

Richard

[Timleech]

I think it is actually the other way around, there is more 'spring' in the traditional one, making it less vulnerable on the cut

 

 

 

Richard

 

Most modern ones are far too light & springy anyway

 

Pet hate of mine.

 

Tim

[Davidss]

That's a bit OTT. Removing all the paint from that is non-trivial and quite possibly not necessary. A reasonable possibility is that someone posts to the effect that "Yes, it's Dursley Widget Co collar, grub screws at 3 o'clock, and 9 o'clock then hit it once just HERE."

 

MP.

You misunderstand me, but I can see why you came to that conclusion.

While writing my comment I looked at the assembly as a whole. I could see, at second glance, the grease nipple that no-one else had mentioned, and the collar the extender was screwed into.

I then looked at the bush welded into the deck, but DUE TO THE DIRT, it is impossible to see clearly whether it is a one piece bush extending up to the 'collar with the grease nipple', or a short bush with a collar above it, clamped to the rudder shaft to hold it in position.

The difference will affect the disassembly procedure.

All it would have taken was a wipe round with a damp cloth, or mop, to remove the dirt.

 

My tartness was caused by the fact I'd started to help, but couldn't complete the task to my satisfaction due to a lack of simple housekeeping. I felt I'd wasted my time (but I'd started, so I finished).

 

I'll let you decide for yourself my feelings on seeing no-one has (yet) come up with a better suggestion, rather they have wandered off onto a theoretical discussion on tiller design, which in too typical CWDF fashion doesn't help the OP at all. I doubt this explanation of my feelings helps much, either, but I'll hide behind the greater distraction :-)

 

I agree with you that if someone recognises the exact design, and knows from experience exactly how disassembly is achieved, then they can give a perfect answer.

However, it's rarely a perfect world, so preparing alternatives seems like a reasonable course of action, especially when it involves such a little investment of energy as a wipe round with a damp cloth or mop.

 

Regards.

[RLWP]

To be honest David, discussing tiller design when the subject arises is just as useful as getting cross about the paint and dirt on the rams head. None of us have any further information to come to a conclusion yet

 

Also, I'm not sure you are allowing for the OP being somewhat traumatised at having nearly lost his boat in a lock. Expecting a fully thought-out presentation of the problem immediately after an experience like that is a bit unreasonable

 

Richard

 

I would have a go at the assembly with a 1" paint scraper, it is probable that most of the paint will just fall off.

Edited May 6, 2012 by RLWP

[MoominPapa]

My tartness was caused by the fact I'd started to help, but couldn't complete the task to my satisfaction due to a lack of simple housekeeping. I felt I'd wasted my time (but I'd started, so I finished).

I understand. In that case I strongly suggest avoiding any CWF electrical threads until you've had much more therapy This is mere bagatelle compared the "my green wires are all curly, do you think that's why I can't run my tumble drier from a knackered 110Ah leasure battery" level that can sometimes be found there.

 

I'll let you decide for yourself my feelings on seeing no-one has (yet) come up with a better suggestion, rather they have wandered off onto a theoretical discussion on tiller design, which in too typical CWDF fashion doesn't help the OP at all. I doubt this explanation of my feelings helps much, either, but I'll hide behind the greater distraction :-)

Wildly diverging threads and occasional grumpiness are both long-standing CWDF traditions. I'm happy to encourage the former and discourage the latter.

 

 

MP.

Edited May 6, 2012 by MoominPapa

[zenataomm]

I have known competent chappies with a set of bottles and a gas axe tackle a similar job from the tow path. However on that occasion the stock level was raised sufficiently above the the top collar to give enough meat to weld a collar onto which then took a new swan neck.

 

I suspect the collar with the grease nipple on originally spun free? But is now rust welded to the rudder post. Perhaps heating the collar up and hitting it with your wife's handbag might free it.

 

Either way I guess it's a boat out of water, remove rudder and take to small engineering outfit with all of the required measurements. If you're not handy at DIY (Destroy it Yourself) again a gas axe will probably be the quickest way to remove the old stock head. Whatever the rudder and post have to come off. To try and save money I'd probably buy myself one of those cheap angle grinders and some discs, then throw the burnt out grinder away after. You may have room to cut the post before it passes through the counter from underneath then there's no need to faff about with the assembly above.

 

The new one will need to be made in order to be passed up through the counter from underneath, then the swan neck attached after. That means you need to decide if it's manufactured so you can assemble yourself or invite the the aforementioned chappies with a box of sparks to weld it in place. If latter don't forget to disconnect the alternator first or you'll be coughing up for one of them as well.

 

Best of luck.

Glad no one was injured or your boat further damaged.

Have you spoken to your insurance company? After all it was an accident.

 

My comments above are merely based on what I have observed others do. Should I have been unfortunate enough to have experienced your bad luck it's the way I'd be thinking. I am not qualified and am probably spouting tosh, as I am sure someone is sure to leap to their keyboard and indignantly point out.

 

However if it results in something a little more helpful being posted, I'm happy to take one for the team.

[bizzard]

The Swans neck could also be there to deter and frighten off Swans from pecking at the legs of an unwary steerer.They'd probably think its a giant Swan.

It must also balance it a bit and distribute the weight of the steerer lolling and dozing off on it for long periods and so help to reduce top bearing wear,but i doubt if this was thought of years ago.

[owen]

Classic error in Thornes Lock today. Too busy showing crew a handspike in the top gate to notice the boat had drifted rearwards far enough for the swans neck to become trapped under the bottom gate walkway and snap off. It did so after holding the rear down by about 8in which fortunately wasn't enough for any water ingress into the hull.

 

 

No amount of fishing with magnets found the arm; so it's down there somewhere. Trouble is, as it's a river lock there's about 10ft of depth as a minimum. Thanks must go to the boat who breasted us up and brought us safely back to the mooring.

 

So - the questions are; how do I get this assembly apart? What am I likely to find inside, and where can I source a replacement neck and bar?

 

Cheers,

 

Dave

hi its possible i can help you with replacement swan neck depending on how quickly you need this sorted the photo you have posted looks like the top bush will come off maybe two screws maybe 9 o clock and 3oclock bit difficult to tell without removing paint once you have this paint removed with scraper wire brush nitromorse you will be able to tell, when this is off you may be able to shorten slightly the next bush if the bearing is not set tight to top with careful cutting with grinder with stainless cutting blade in it may then be possible to drill and tap top of spigot for decent bolt then attach new piece of spigot and weld round the sides the bolt is just to add a bit of central strength it is difficult to say without seeing it cleaned off where on calder and hebble are you

[Neil2]

Wildly diverging threads and occasional grumpiness are both long-standing CWDF traditions. I'm happy to encourage the former and discourage the latter.

 

 

MP.

 

 

I'd agree with that.

 

Until I read this post I had never given the swan neck tiller design much thought - you don't find them on other types of boat and when you think about it it's just something else to get caught up in a lock as we have witnessed.

 

I was thinking about other boats that are commonly steered by tiller, ie yachts, and I've never seen a curly tiller on a yacht. But then yachts are designed to be steered sitting down. Is it just that narrowboats are designed to be steered standing up, and in order to raise the tiller to that height it needs some bend in it to enhance rigidity/strength?

 

I read somewhere that the curve was so that the tiller cleared the coal box on working boats which was usually on the stern counter but I don't buy that. I just can't see why we can't have "straight" tillers.

 

There was a recent thread on wheel steering wasn't there? Seems to me a straight tiller would be much easier to adapt than a swan neck.

 

Also a straight tiller would be potentially easier to adjust for height - another big disadvantage of the swannie. I fact I can't think of a good reason for having a swan neck tiller but there must be one.

 

Mustn't there?