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Drilling holes through the rudder stock


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Posted (edited)

It was built by a forum member about 15 years ago. He made several for other members of this forum including Daniel I think? (I might have that wrong)

 

I'm guessing it's 3mm because of its weight and I'm not sure how he'd have rolled 4mm steel to get the curved profile. But 2 x 3mm is 6mm and I've seen plenty of single plate rudders made from 6mm plate.

 

I don't think I've ever hit my rudder on anything. Isn't yours protected with a stern fender? But it's a fair point. It's not going to be as strong as the old rudder. 

Edited by blackrose
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Your post read as if it was a single 3mm plate. If its two plates spaced apart it will certainly be stronger.

 

Have you never winded your boat in a winding hole or at a junction where the depth against the towpath wall is barely adequate? Often the rudder is the first thing to touch, long before the stern fender reaches the bank.

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Posted (edited)
7 minutes ago, David Mack said:

Your post read as if it was a single 3mm plate. If its two plates spaced apart it will certainly be stronger.

 

Have you never winded your boat in a winding hole or at a junction where the depth against the towpath wall is barely adequate? Often the rudder is the first thing to touch, long before the stern fender reaches the bank.

 

Sorry for the misunderstanding. There's a picture of the new rudder profile on my original post on this thread.

 

Yes the bottom of the rudder won't always be protected in every situation.

 

Would you fit the new one then or not? It's a bit of a dilemma for me. I don't think the trailing edge of the new rudder where the two plates come together will be stronger. 

Edited by blackrose
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11 minutes ago, David Mack said:

Your post read as if it was a single 3mm plate. If its two plates spaced apart it will certainly be stronger.

 

 

I thought similar to you until I read the post :

 

The old rudder is made from 10mm plate and I think the new one is 3mm on both sides so it's lighter and I guess not as strong.

 

Maybe "3mm EACH side" would have been clearer but I understood what he was saying.

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Sorry I see how the misunderstanding arose. I think "each side" would have been just as ambiguous.

 

I meant 3mm on each side of the hole for rudder stock when the rudder profile is viewed from above. Anyway the picture in my original post shows it better than I can explain it. 

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1 minute ago, Tracy D'arth said:

That ring eye will knock hell out of the edge of the uxter plate if you have no stops.

 

Well the uxter plate always acted as the stops for the old rudder. It took a small area of paint off the edge of the plate on each side, that was all. 

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It seems to me that two pinch bolts into countersinks will do what they all do in time.  Fret at the ends as the rudder vibrates in the normal way, wear the countersinks  larger and the pinch bolts shorter so that the blade moves  on the stock.  Adding 'a bit of weld' to prevent this is fine, till you need to get it apart, in the water.  If you never, ever, ever need to get it apart in the water then forget the pinch bolts and  just weld it on.

 

An alternative would be to flange the top and bottom of the rudder and fit corresponding flanges to the rudder stock, removing the piece of stock between the flanges, then bolt it all up.  You will be able to remove the rudder OK but changing the top bearing might be difficult.

 

 Transom Springers had a similar arrangement where the rudder stops were the blade hitting the transom.  This is/was a known wear point, leading to a leak onto the counter inside, easily cured with an over patch and prevented by fitting a bit of round bar to the edge of the rudder where it hit the patch.  That said, the Springers were thinner, and  only had about 90 degrees of rudder movement in total, so the impacts were frequent.

 

N

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Posted (edited)
1 hour ago, BEngo said:

It seems to me that two pinch bolts into countersinks will do what they all do in time.  Fret at the ends as the rudder vibrates in the normal way, wear the countersinks  larger and the pinch bolts shorter so that the blade moves  on the stock.  Adding 'a bit of weld' to prevent this is fine, till you need to get it apart, in the water.  If you never, ever, ever need to get it apart in the water then forget the pinch bolts and  just weld it on.

 

An alternative would be to flange the top and bottom of the rudder and fit corresponding flanges to the rudder stock, removing the piece of stock between the flanges, then bolt it all up.  You will be able to remove the rudder OK but changing the top bearing might be difficult.

 

 Transom Springers had a similar arrangement where the rudder stops were the blade hitting the transom.  This is/was a known wear point, leading to a leak onto the counter inside, easily cured with an over patch and prevented by fitting a bit of round bar to the edge of the rudder where it hit the patch.  That said, the Springers were thinner, and  only had about 90 degrees of rudder movement in total, so the impacts were frequent.

 

N

 

Thanks for this. It was always welded on before so I would never have been able to get it off in the water. Perhaps I'll just do the same again.

 

I'm not sure I understand what you mean by flanging the top and bottom of the rudder and fitting corresponding flanges to the rudder stock? There's not a lot of room to do much at the top & bottom of the new rudder. 

Edited by blackrose
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Posted (edited)
1 hour ago, BEngo said:

An alternative would be to flange the top and bottom of the rudder and fit corresponding flanges to the rudder stock, removing the piece of stock between the flanges, then bolt it all up.  You will be able to remove the rudder OK but changing the top bearing might be difficult.

 

Ok I get it now.. Chopping the rudder stock seems a bit drastic though. Can you imagine trying to unbolt it in the water, especially at the bottom?

 

I don't think there's really enough room for the flanges and bolts on mine 

Edited by blackrose
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Looking at your photo again it seems hat, as-is, there will not be enough room for any flanges.  In fact it looks like it could be interesting trying to weld the rudder to the stock without also welding the whole lot to the rudder tube!  Might be worth shortening the down stand of the rudder tube below the counter a bit to give better access.

 

N

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1 minute ago, BEngo said:

Looking at your photo again it seems hat, as-is, there will not be enough room for any flanges.  In fact it looks like it could be interesting trying to weld the rudder to the stock without also welding the whole lot to the rudder tube!  Might be worth shortening the down stand of the rudder tube below the counter a bit to give better access.

 

N

 

 

Yes I might have to do that. Thanks. 

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Posted (edited)

With this arrangement what prevents the rudder coming out of the skeg cup if the rudder hits something? It has to lift out of the cup easily to remove the rudder so there needs to be plenty of room between the rudder and uxter plate. 

 

image.png.88981224523a994fd170ca968591a41e.png

 

I was thinking that if I cut off most of the protruding rudder stock tube under my uxter plate I could get a swan neck/rudder stock taper made at a later time.

 

The downside of this design seems to be that the rudder can easily become dislocated from the skeg, or is that not the case? 

 

Edited by blackrose
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56 minutes ago, blackrose said:

With this arrangement what prevents the rudder coming out of the skeg cup if the rudder hits something? It has to lift out of the cup easily to remove the rudder so there needs to be plenty of room between the rudder and uxter plate. 

 

image.png.88981224523a994fd170ca968591a41e.png

 

I was thinking that if I cut off most of the protruding rudder stock tube under my uxter plate I could get a swan neck/rudder stock taper made at a later time.

 

The downside of this design seems to be that the rudder can easily become dislocated from the skeg, or is that not the case? 

 

The top ball race would stop the stock lifting off the skeg cup as the inner bearing track is normally grub screwed to the stock. Even if it isn't the inner bearing track is usually jambed on the stock needing heat, oxy-acetylene and a puller to yank them up anf off. I had to do this on two boats recently. Of course if the top bearing ball race is knackered and corroded away, as many are after years of use the stock would probably just heave up through it.

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14 minutes ago, bizzard said:

Of course if the top bearing ball race is knackered and corroded away, as many are after years of use the stock would probably just heave up through it.

Or if you have an ex-working boat, with a loose fitting plain bearing...

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Posted (edited)
29 minutes ago, bizzard said:

The top ball race would stop the stock lifting off the skeg cup as the inner bearing track is normally grub screwed to the stock. Even if it isn't the inner bearing track is usually jambed on the stock needing heat, oxy-acetylene and a puller to yank them up anf off. I had to do this on two boats recently. Of course if the top bearing ball race is knackered and corroded away, as many are after years of use the stock would probably just heave up through it.

 

A grub screw doesn't sound like it would stop the rudder lifting out of the cup if it hit something. But anyway, how would you intentionally lift the rudder out? It sounds like it's quite an operation? Would you have to loosen the bearing grub screw first for example, or just unbolt the bearing from the deck? 

 

 

Edited by blackrose
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9 minutes ago, blackrose said:

 

A grub screw doesn't sound like it would stop the rudder lifting out of the cup if it hit something. But anyway, how would you intentionally lift the rudder out? It sounds like it's quite an operation? Would you have to loosen the bearing grub screw first for example, or just unbolt the bearing from the deck? 

 

 

If you've never ever removed the rudder stock, grub screw or not it will almost certainly be seazed on. You can unbolt the bearing to lift the whole lot up a bit until the rudder hits the uxter plate. Those bearings are not really marine bearings for rudders. Ball and roller bearing units are meant to revolve around and around completely, not like a trunion only half way or so and back. If the bearing is knackered needing renewal and the inner track is seazed on and you've unbolted and lifted the stock up an angle grinder with metal cutting disc to cut through one side of the track which will then pull up and and off easily.  I find a puller and oxy-acetelene quicker.

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To be honest even with the correct rudder arrangement, the idea of being able to remove the rudder with the boat in the water sounds like it's almost as much hassle as having to get the boat out of the water. I guess the big advantage is that even though it's a struggle it can be done without having to move a non-steering boat. 

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Heating the inner track to expand it with Oxy you only heat fast up and down on one side about 1/2'' width. Heating all around it will heat the stock too much and it still probably will not budge. Propane and Butane too slow and not hot enough.

2 minutes ago, blackrose said:

To be honest even with the correct rudder arrangement, the idea of being able to remove the rudder with the boat in the water sounds like it's almost as much hassle as having to get the boat out of the water. I guess the big advantage is that even though it's a struggle it can be done without having to move a non-steering boat. 

Have you always kept the top bearing greased and is it firm with no side wobble.

2 minutes ago, bizzard said:

Heating the inner track to expand it with Oxy you only heat fast up and down on one side about 1/2'' width. Heating all around it will heat the stock too much and it still probably will not budge. Propane and Butane too slow and not hot enough.

Have you always kept the top bearing greased and is it firm with no side wobble.

You never know it might slide out of that bearing easily, rare but worth a try.

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The arrangement in the sketch is a triumph of expediency over simplicity.

The 'wrong' item is the ball bearing at the top of the stock. it is wholly unnecessary  and only there because it is easier for cheapskate boat builder to buy an (unsuitable) bearing and housing than to get a (probably bespoke) collar and plain bearing to fit the rudder tube.

 The sketchec set up requires the bearing grub screw to stop the rudder being forced out of the cup.  That is poor engineering in itself  as grub screws are not suitable for that sort of job.  A plain bearing set up allows the rudder to go up, but in my experience it usually drops back without a problem.  If the stock  misses the cup it is not hard to recognise  this and easy to get back in its proper 'ole with a shoulder under the tiller.

 

N

 

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Posted (edited)
14 minutes ago, BEngo said:

The arrangement in the sketch is a triumph of expediency over simplicity.

The 'wrong' item is the ball bearing at the top of the stock. it is wholly unnecessary  and only there because it is easier for cheapskate boat builder to buy an (unsuitable) bearing and housing than to get a (probably bespoke) collar and plain bearing to fit the rudder tube.

 The sketchec set up requires the bearing grub screw to stop the rudder being forced out of the cup.  That is poor engineering in itself  as grub screws are not suitable for that sort of job.  A plain bearing set up allows the rudder to go up, but in my experience it usually drops back without a problem.  If the stock  misses the cup it is not hard to recognise  this and easy to get back in its proper 'ole with a shoulder under the tiller.

 

N

 

 

Yes I see, thanks. Do you think I could get my one piece LB rudder stock/swan neck modified so that it resembles the arrangement in the sketch at a later time? If so I'll just fully weld the new rudder to the stock. 

 

I don't really see the point of the cone shaped taper. Can't that slip? 

Edited by blackrose
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And it dosen't matter too much if the skeg cup and the stock tube are not perfectly lined up using those self centering ball races, easy way out.

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Posted (edited)

My boat has been out the water for a week but it was back in the water for an hour today as the yard owner needed to move some boats around using the slipway, so I took the opportunity to test the new rudder.

 

It was temporarily held onto the stock with 2 pinch bolts for the test. In terms of steering there's very little difference compared to the old rudder apart from I've now got about 5 degrees greater arc on each side before the new tiller hits the stops. At low revs that extra tiller angle works but at higher revs I can see that some of the water isn't moving over the rudder but is going the other way. It still works in terms of moving the stern but it works better with slightly less rudder angle so I guess the rudder is starting to stall at its maximum angle at higher revs so I've probably got the stop angles about right. 

 

The other difference with the new rudder is that it feels smoother than the old one. Much less tiller vibration. It must be the profile shape.

 

Since most people are agreed that even precision drilled holes & bolts through the rudder stock will eventually lead to a sloppy rudder I've decided not to bother. As it has to be welded to the rudder stock anyway it seems pointless to add more holes. It's already got two holes through it and one of the new holes would be in a different position so it would end up like Swiss cheese and weaker. I'll just use two pinch bolts to secure it and a bit of weld top and bottom. 

 

IMG_20220802_151722.jpg

 

IMG_20220730_120413.jpg

 

Before installing it I'm going to drill a couple of holes in the top, tap the holes and pump a load of this stuff in and fill it up before screwing in a couple of stainless bolts to close the holes. It will be plenty strong enough. 

 

https://www.screwfix.com/p/rawlplug-r-kem-ii-styrene-free-polyester-resin-300ml/32863

Edited by blackrose
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