Why?

[tidal]

I've been looking at butties (buttys?) and the large rudders on them.

I am aware that they are necessary because, being unpowered, they do not have propwash to deflect so need a bigger are so that the craft can be steered effectively

 

I have also been looking at motors, and the rudder on them. I presume that they have such small rudders by comparison because they do have propwash to deflect AND a larger rudder would have been a bit in the way and vulnerable when part of a traditional pair.

 

Now years ago I had the wonderful opportunity to steer a butty converted to motor which retained its old rudder. It was wonderfully sensitive, slightly dangerous but steerable (well reasonably so) in reverse and when,(as often happened) the temperamental petrol engine died it would keep steering long enough to make a sensible choice of temporary mooring AND allow one to avoid passing or moored cruisers.

 

So why do narrowboat motors not have the larger rudder?

 

Tradition?

 

I'm curious and am still tinkering with a design for a one-off bespoke built boat (I've now found the bow shape I want) so want to see what, if any improvements I can make to the steering and overall handling

[tidal]

Hmmmm

 

Obviously not a very bright question.

[Liam]

The larger "butty" rudders tend to be both self cantering and have fixing points at the top and bottom. I know normal motor rudders do, too, but they're out of the way under the counter and aren't as cumbersome. They probably didn't "back in the day" as I don't think they'd last too long with buttys running into them... just looking at some of the rather dented counters tells it's own story. It'd most likely get in the way of the cross straps too.

 

I'm sure there are other reasons why but those are the first which came to me.

[tidal]

Yes

I can see the logic of that and thanks Liam

 

Does anyone think that there would be any handling improvements or problems with fitting such a rudder design to a modern motor which is unlikely to ever be part of a pair?

 

I am sure I am missing something, just can't think what it is........

[Proper Job]

A butty rudder is not balanced. All of the blade is behind the fulcrum (hinge point) and it needed a relitively large tiller in front of the fulcrum to allow ease of movement. In comparison to the forces exerted on the rudder blade, it is a lot less than those experience by a motor rudder (prop wash)

 

A motor set up has a section of the rudder blade in front of the fulcrum (under the counter) to 'balance' the effect of the pressure of the prop wash on the overal rudder blade area. Additionally, if you follow the line of the fulcrum up, it has a relitively short tiller in comparions to the forces exerted on it by the prop wash.

[Athy]

Ah, hence the blooming enormous tillers which butties have. Is there also a reason why these tillers are always curved? It can't just be so that you can invert them and keep them out of the way when you're moored - or can it?

[carlt]

Ah, hence the blooming enormous tillers which butties have. Is there also a reason why these tillers are always curved? It can't just be so that you can invert them and keep them out of the way when you're moored - or can it?

So they are in the correct position, when you're steering and can go conveniently out of the way, when moored.

 

A butty rudder has less surface area, underwater, when empty, than a motor, btw.

[tidal]

A butty rudder has less surface area, underwater, when empty, than a motor, btw.

 

But more when loaded?.. or set down to the "correct" position on a "loaded" motor?

 

I had noted the lack of balance area, but having used similar un-balanced stern hung "spade" rudders I presumed that, like those, a long tiller would compensate in terms of control of the rudder,

 

Would note the extra submerged area more than compensate for the lack of the balanced area?

 

Were all butty rudders flat or were they slightly aerofoiled in cross section?

Currently I am only looking at pictures and flat side view plansand my memory of the "real" thing is slightly blurred.

 

Are there still any motorised buttys out there with original rudders?

[carlt]

But more when loaded?.. or set down to the "correct" position on a "loaded" motor?

 

I had noted the lack of balance area, but having used similar un-balanced stern hung "spade" rudders I presumed that, like those, a long tiller would compensate in terms of control of the rudder,

 

Would note the extra submerged area more than compensate for the lack of the balanced area?

 

Were all butty rudders flat or were they slightly aerofoiled in cross section?

Currently I am only looking at pictures and flat side view plansand my memory of the "real" thing is slightly blurred.

 

Are there still any motorised buttys out there with original rudders?

Lots more, when loaded.

 

I don't understand what you mean by "balanced area"

 

All traditional butty rudders were flat plain sawn planks.

 

There are plenty of motorised butties still about. They have "fishplates" to stop cavitation. The one I owned was one of the easiest steering boats I've ever piloted.

[koukouvagia]

There are plenty of motorised butties still about. They have "fishplates" to stop cavitation. The one I owned was one of the easiest steering boats I've ever piloted.

 

The problem with motorised butties is that you have to get a propshaft through the hull somehow. There is usually very little room for this. Also I don’t like the idea of cutting into an historic hull. An alternative is to have a hydraulic motor in the ellum. You get fantastic handling – it’s just like a giant outboard- and you preserve the hull.

 

 

http://tinyurl.com/5a9tk4

 

http://tinyurl.com/5nla2g

[ditchcrawler]

The problem with motorised butties is that you have to get a propshaft through the hull somehow. There is usually very little room for this. Also I don’t like the idea of cutting into an historic hull. An alternative is to have a hydraulic motor in the ellum. You get fantastic handling – it’s just like a giant outboard- and you preserve the hull.

 

 

http://tinyurl.com/5a9tk4

 

http://tinyurl.com/5nla2g

I spoke to the owner of a converted butty with a hydraulic motor in the rudder blade. She said it was very maneuverable but heavy and could do with "powered steering.

I understand they have since sold the boat and I am racking my brains to remember its name.

[alan_fincher]

I spoke to the owner of a converted butty with a hydraulic motor in the rudder blade. She said it was very maneuverable but heavy and could do with "powered steering.

I understand they have since sold the boat and I am racking my brains to remember its name.

"Leonids" is one possibility of a converted butty with hydraulic drive, I think.

[tidal]

I don't understand what you mean by "balanced area"

Carl

my apologies written in a hasty way to reply to an earlier post and the termonology wasn't right

I was referring to the balance area of a standard motor rudder forward of the pivot point

 

I was actually thinking of a similar profiled stern with a stern-hung rudder bring ing the engine and prop further back to increase useable space AND possibly improving the handling (similar to double-enders used in the baltic lagoons?)

 

I wasn't aware of the hydraulic drives........anyone got pics?

edited to say that the tiny links don't work for me

Edited October 22, 2008 by tidal

[Arnot]

I've been looking at butties (buttys?) and the large rudders on them.

I am aware that they are necessary because, being unpowered, they do not have propwash to deflect so need a bigger are so that the craft can be steered effectively

 

I have also been looking at motors, and the rudder on them. I presume that they have such small rudders by comparison because they do have propwash to deflect AND a larger rudder would have been a bit in the way and vulnerable when part of a traditional pair.

 

Now years ago I had the wonderful opportunity to steer a butty converted to motor which retained its old rudder. It was wonderfully sensitive, slightly dangerous but steerable (well reasonably so) in reverse and when,(as often happened) the temperamental petrol engine died it would keep steering long enough to make a sensible choice of temporary mooring AND allow one to avoid passing or moored cruisers.

 

So why do narrowboat motors not have the larger rudder?

 

Tradition?

 

I'm curious and am still tinkering with a design for a one-off bespoke built boat (I've now found the bow shape I want) so want to see what, if any improvements I can make to the steering and overall handling

My boat "Orianne" is an ex horse drawn barge that was motorised by the installation of a large diesel and a large prop with fish plates for the reduction of cavitation. All the work was done below the water line (more or less) and so the original look of the hull is retained. Whilst it has been replaced, the rudder is as the original would have been and the tiller is the appropriate long curved bar.

 

As you observe, "It is wonderfully sensitive, slightly dangerous but steerable (well reasonably so) in reverse and when,(as often happenes) the temperamental diesel engine dies it will keep steering long enough to make a sensible choice of temporary mooring AND allow one to avoid passing or moored cruisers". In fact it will steer even to a standstill with a bit of work on the tiller which is useful when dawdling up to locks, it saves all that messing about with ropes and jumping around and the time can be constructively spent in rolling a fag! In fact on calm water in good weather, it is a delight and can be taken through bridge holes with less than an inch to spare with absolute certainty.

 

There are a couple of down sides though, one is that if you forget and apply a few revs when the rudder is more than 10 ish degrees from straight, the tiller tries to eject you from the back of the boat and possibly into orbit. If you don't have a tight hold, you will get very bruised.

 

The other down side is that when ploughing shallow ditches you have to continuously wrestle with the tiller to keep the thing in a more or less forward direction and after a few hours it can get damned tiring and the margin of control can get remarkably thin... You have to roll your fags in advance under these conditions.

 

Another phoenomenon is that as with most boats of this nature, Orianne is about as big as narrow boats get and very heavy. The consequence of this along with the large rudder is that when you make a correction, there is a significant delay before any effect is aparrent and when it does start to happen, it doesn't stop quickly. This isn't really a problem but it does require a good level of anticipation. This effect has an added frisson when under power when the wash effect of the large prop throws the back out when turning one way and the front out when turning the other, and of course this effect varies with speed, power and other variables.

 

Since I work with boats for a living and often steer all sorts, despite the fact that I love Orianne to bits and love cruising her, I have to accept that it isn't the easiest job in the world. The more conventional motor counter with a balanced rudder and "Z" tiller is easier by far.

 

The reason for the curve in the tiller bar is, as stated, to reverse it when moored. The importance of this is firmly impressed in your cranium when you forget and get out of the low back cabin to answer the call of nature in the middle of the night. The effect will bring stars to even the cloudiest of nights.

 

I suspect that motor boats have the layout they do is so as not to knacker the crew. I have to say that if I had to use Orianne as a full time working boat, I would sacrifice the looks for comfort and practicality PDQ. As it is, when it gets tiring I just stop a while or go dead slow when it is far easier.

 

Hope this helps in your design considerations,

 

Regards

 

Arnot

Edited November 6, 2008 by Arnot

[carlt]

The problem with motorised butties is that you have to get a propshaft through the hull somehow. There is usually very little room for this. Also I don’t like the idea of cutting into an historic hull. An alternative is to have a hydraulic motor in the ellum. You get fantastic handling – it’s just like a giant outboard- and you preserve the hull.

 

 

http://tinyurl.com/5a9tk4

 

http://tinyurl.com/5nla2g

One hole, through the stern-post that is easily plugged, if you wanted to deconvert.

 

I agree that it is a shame to alter a butty, in this way, but, if it wasn't possible, there'd be a lot less full-length butties, surviving.

 

Also, if Taplow's anything to go by, they swim beautifully.

[Hairy-Neil]

"Leonids" is one possibility of a converted butty with hydraulic drive, I think.

 

GU's 'Aston' and 'Capella' also have them. Have also seen a Josher or two with them fitted.

[koukouvagia]

GU's 'Aston' and 'Capella' also have them. Have also seen a Josher or two with them fitted.

 

One of the joshers is Hampton. There's also Lincoln.

[tidal]

Thanks for all the comments to date, they have given me a lot to think about.....and especial thanks for the comments from those who actually have cruised with this rudder style as there were some parts of the handling I hadn't considered

 

I am still looking hard at the concept of a stern hung rudder, especially on a shorter boat with less worries about cills etc