Articulated Rudder

[Trento]

On the next dry docking I'm thinking to install an articulated rudder. IM given to understand that such a device can greatly reduce the boats turning circle, plus assist in close manoeuvres with and alongside onther vessels.

Has anyone here installed such a rudder, or, have any experience with them ?

 

[NB Lola]

Is there a paper on this, am interested!

[Alan de Enfield]

1 minute ago, NB Lola said:

Is there a paper on this, am interested!

 

 

Alternative design

 

 

[NB Lola]

Ok, so it intensifies the water resistance to tighten the turning circle.  Not sure how effective this would be with low speed manoeuvres. 

[Graham Davis]

Or how well it would cope with the rubbish found in canals.

Two principles come to mind: KISS and "if it ain't broke don't fix it".

[Alan de Enfield]

11 minutes ago, Trento said:

IM given to understand that such a device can greatly reduce the boats turning circle,

The 'thing' that tends to limit the turning on a NB is the length - when you have a 60 foot boat in a 50 foot wide canal, the best rudder in the world will not allow you to turn around.

[Tony Brooks]

39 minutes ago, NB Lola said:

Ok, so it intensifies the water resistance to tighten the turning circle.  Not sure how effective this would be with low speed manoeuvres. 

I think it will act more like a flap on an aircraft wing and increase the lift (sideways force) at low speed.

[Mike Todd]

18 minutes ago, Tony Brooks said:

I think it will act more like a flap on an aircraft wing and increase the lift (sideways force) at low speed.

I was just about to make the same comment!

[ditchcrawler]

Well the barges on the continent use to fit them

[MtB]

34 minutes ago, Tony Brooks said:

I think it will act more like a flap on an aircraft wing and increase the lift (sideways force) at low speed.

 

Me too, and as such it will possibly reduce the diameter of the turning circle, but probably not by more than perhaps 20%

 

The thing is though, how many times a day would the OP's narrowboat  benefit from the reduced turning circle, at the expense of increased complexity and risk of jamming/failure? I'm not sure I've EVER 'almost' got round in one, but not quite and wished I'd had an articulating rudder. 

 

Dear OP, as you seem to like stuff that is overcomplicated, can I interest you in a thermal store heating system for your boat?

[Ex Brummie]

Maybe it is my rudder, but I don't think so, but if I turn it full one way, then I see the prop pushing water past the short end. I can't see that an articulated rudder would affect that. I find the optimum turning circle is obtained at about 45 degrees.

[ditchcrawler]

Just now, Ex Brummie said:

Maybe it is my rudder, but I don't think so, but if I turn it full one way, then I see the prop pushing water past the short end. I can't see that an articulated rudder would affect that. I find the optimum turning circle is obtained at about 45 degrees.

But surly that 45 deg on the main rudder for minimum blow past with an articulated rudder you would still get more turning action from the tip

[Detling]

Cruise ships have 3 or 4 step articulated rudders if they haven't got pods.  It enables them to go virtually sideways at the stern, with bow thrusters they can get too very tight spaces and turn in their own length. But not seen one on a narrow boat.

Edited November 22, 2018 by Detling
Autocorrect got it wrong

[Trento]

I hardly consider a narrowboat based articulated rudder "over complicated", but I guess each to his own.

For a long as we are blessed with "constant moorers" who are now utilising the "free space" in a winding hole

I would rather not have to perform a 19 point turn running the risk of waking them up, or worse touching their boat, I think the "complicated, rudder has merit.

 

[John Hartley]

Several things come to mind. With the use of my bow thruster and standard rudder I can travel sideways without to much trouble. There is then the consideration of extra drag cause by the extra articulation. Not a lot but over the life of the boat could add up to a considerable amount of extra fuel. If the OP is considering alterations to make his boat more maneuverable then perhaps he should consider a Kort Knozzle. That would help going forward and also in reverse.

[ditchcrawler]

10 minutes ago, John Hartley said:

Several things come to mind. With the use of my bow thruster and standard rudder I can travel sideways without to much trouble. There is then the consideration of extra drag cause by the extra articulation. Not a lot but over the life of the boat could add up to a considerable amount of extra fuel. If the OP is considering alterations to make his boat more maneuverable then perhaps he should consider a Kort Knozzle. That would help going forward and also in reverse.

I would suggest less drag as for any given turn you would require less rudder angle.

[John Hartley]

I agree that during the turn much less drag. But under normal operation going forward the mechanism will produce more drag. Most of the time your sailing the rudder is at or near straight ahead producing more drag than is saved during a maneuver.

J

5 minutes ago, ditchcrawler said:

I would suggest less drag as for any given turn you would require less rudder angle.

Johnh

[MtB]

The drawback I can see developing is the likelihood of those sliding groove mechanisms top and bottom getting jammed with items of debris stirred up off the bottom when turning. 

 

Or catch the rudder on a sill in a lock bending the rudder mech ever so slightly, and suddenly you'll have no steering. 

There is enough trouble with ordinary plain rudders let alone complex devices like this!

[Bee]

3 hours ago, ditchcrawler said:

Well the barges on the continent use to fit them

They certainly do, and also twin rudders, the rudder on our boat is an aerofoil section, I think almost anything is better than a flat plate of steel but trying to test it with lots of calculations looks like a mathematical nightmare.  I would imagine a bowthruster would be the best way of tightening a turning circle. It would be interesting to fit a bow rudder, cut away an aperture just behind the stempost and pivot it in that protected area. ( interesting but hardly practical as it would be ineffective at low speed and collect huge amounts of weed)  Or, best of all, lots of fenders and say sorry when you bump things.

[ditchcrawler]

1 hour ago, Bee said:

They certainly do, and also twin rudders, the rudder on our boat is an aerofoil section, I think almost anything is better than a flat plate of steel but trying to test it with lots of calculations looks like a mathematical nightmare.  I would imagine a bowthruster would be the best way of tightening a turning circle. It would be interesting to fit a bow rudder, cut away an aperture just behind the stempost and pivot it in that protected area. ( interesting but hardly practical as it would be ineffective at low speed and collect huge amounts of weed)  Or, best of all, lots of fenders and say sorry when you bump things.

Didn't Dan make a profiled rudder

[Horace42]

........but do they help when going backwards....that's where I could do with some help with steering.

[Sea Dog]

6 hours ago, Horace42 said:

........but do they help when going backwards....that's where I could do with some help with steering.

Don't worry Horace, I'll help you.

 

[Tony Brooks]

13 hours ago, Ex Brummie said:

Maybe it is my rudder, but I don't think so, but if I turn it full one way, then I see the prop pushing water past the short end. I can't see that an articulated rudder would affect that. I find the optimum turning circle is obtained at about 45 degrees.

The 45 degree thing seems to be because rudders tend to work in two different ways. Up to about 45 degrees the rudder causes a hydrodynamic effect similar to an aircraft wing so the water flow creates a low pressure area on one side that pushes the boat round. At a greater angle the hydrodynamic effect stalls just like an aircraft with at too slow a speed so that push is lost. But you still have a sort of off set breaking or dragging effect and possibly a directed jet effect from the prop wash at greater angles.  The difference between the two effects will probably be most seen at low speed with the power off, not something narrowboaters tend to do very often. I think the moving trailing edge would allow a greater than about 45 degree of rudder before it stalls.

[Sea Dog]

16 hours ago, NB Lola said:

Ok, so it intensifies the water resistance to tighten the turning circle.  Not sure how effective this would be with low speed manoeuvres. 

And there are certainly no other types of manoeuvre with a narrowboat! 

[koukouvagia]

I know it's not strictly relevant to this thread, but one way to ensure a 70' boat can pivot 180 degrees on the spot, can go sideways into a mooring and can steer in a straight line backwards is to have a butty with an hydraulic motor in the rudder .