Jump to content

Articulated Rudder


Trento

Featured Posts

15 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.

Agreed.  All too often you see people trying to wind with the tiller pushed right over, engine revving like mad and 55% of the prop wash going one way and 45% the other.  I've even seen the so-called instructor on a boat handling course doing it.

 I find about 45 degrees about right. Sometimes you need to give the rudder a little wiggle to get the flow to attach to the rudder blade (as according to somebody's principle - Bernoulli? ) and then all the thrust is put out sideways. If I get it right, the boat will turn in practically its own length. Very satisfying ( but doesn't always happen)!

  • Greenie 1
Link to comment
Share on other sites

9 minutes ago, dor said:

Agreed.  All too often you see people trying to wind with the tiller pushed right over, engine revving like mad and 55% of the prop wash going one way and 45% the other.  I've even seen the so-called instructor on a boat handling course doing it.

 I find about 45 degrees about right. Sometimes you need to give the rudder a little wiggle to get the flow to attach to the rudder blade (as according to somebody's principle - Bernoulli? ) and then all the thrust is put out sideways. If I get it right, the boat will turn in practically its own length. Very satisfying ( but doesn't always happen)!

 

Not all boats behave like this. I find full rudder deflection (approx 80 degrees) delivers a LOT more sideways force than 45 degrees deflection. Also I get less forward motion for the amount of sideways force at full rudder deflection when spinning the boat around on its axis.

 

So I'm one of those you will see using full rudder defection when winding.  

Link to comment
Share on other sites

8 minutes ago, Mike the Boilerman said:

 

Not all boats behave like this. I find full rudder deflection (approx 80 degrees) delivers a LOT more sideways force than 45 degrees deflection. Also I get less forward motion for the amount of sideways force at full rudder deflection when spinning the boat around on its axis.

 

So I'm one of those you will see using full rudder defection when winding.  

It all depends on a variety of factors - swim shape, prop size, rudder shape, water depth, wind direction and speed, shopping trolleys in the way...

 

I do agree though that many people use too much steering and too many revs to make a turn.  The correct angle - which usually isn't a right angle! - requires a lot less churning up the mud to spin round.

 

The easiest way to find the most effective angle is to "row" the tiller through it's range of motion.  You can usually feel the point where it gives the most turning force, but if not keep "rowing" about where you think it should be.

Link to comment
Share on other sites

28 minutes ago, dor said:

Agreed.  All too often you see people trying to wind with the tiller pushed right over, engine revving like mad and 55% of the prop wash going one way and 45% the other.  I've even seen the so-called instructor on a boat handling course doing it.

 I find about 45 degrees about right. Sometimes you need to give the rudder a little wiggle to get the flow to attach to the rudder blade (as according to somebody's principle - Bernoulli? ) and then all the thrust is put out sideways. If I get it right, the boat will turn in practically its own length. Very satisfying ( but doesn't always happen)!

Yes, on most of the boat manoeuvring that I do, I usually find that at the tiller, less is more.

 

 

Link to comment
Share on other sites

15 minutes ago, Mike the Boilerman said:

 

Not all boats behave like this. I find full rudder deflection (approx 80 degrees) delivers a LOT more sideways force than 45 degrees deflection. Also I get less forward motion for the amount of sideways force at full rudder deflection when spinning the boat around on its axis.

 

So I'm one of those you will see using full rudder defection when winding.  

Fair enough.. But presumably when you have your rudder hard over you are not splitting the prop wash almost equally.  I suspect it might be influenced by how much area there is on the rudder in front of the rudder post.

Now then, how about fitting an azimuth pod instead of a rudder?  There was a boat at Stourport years ago ago that had some sort of arrangement (props in tubes?) at both ends which allowed the boat to be moved in any direction.

Link to comment
Share on other sites

Just now, dor said:

Now then, how about fitting an azimuth pod instead of a rudder?  

There's one near me.   Full 360 degree rotation of the propeller makes it very manoeuvrable at low speeds, but he can't steer in a straight line for more than about 10 yards.

 

I really want to have a play with it, but I haven't seen him since the day it was craned in and he set off vaguely in the direction of his mooring. :D

 

Link to comment
Share on other sites

22 hours ago, Trento said:

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.

 

 

I always make a point of reversing into and lightly touching boats moored in winding holes. If they come out shouting at me, it gives me an opportunity to tell them the error of their ways.

 

 If no one tells them what their doing wrong it is unlikely that they will change their ways.

Edited by cuthound
To unmangle the effects of autocorrect.
  • Greenie 4
Link to comment
Share on other sites

On 22/11/2018 at 21:57, ditchcrawler said:

Didn't Dan make a profiled rudder

Yes, we have a Schilling profile rudder on Emily Anne fitted by yours truly after a forum member kindly pressed up the profiled plates. 

 

I then wrote a wiki article for the topic. 

https://en.m.wikipedia.org/wiki/Schilling_rudder

 

Articulated flap rudders look fun, but on a boat where the bottom and edges are so available for minor collision and where a drydock is costly and only scheduled ever four years it didn't seem feasible to me, certainly not given we already have enough to look after with the steam plant. Different ball game with a trailable launch or if you want something fun to play with. 

 

Daniel

 

Link to comment
Share on other sites

6 minutes ago, rusty69 said:

 "Like all rudders, the main effect of a Schilling rudder is to deflect the flow of water generated by the propeller."

 

Best not get one for my sailing dinghy then. 

Feel free to improve the article!

As I noted in the discussion page, this should not be hard. 

 

 

Daniel

Link to comment
Share on other sites

14 minutes ago, Trento said:

Humm, it seems to my mind that given the drawings and photos of the articulation that the extension to the Skeg, necessary for the articulation to work would go some way in protection of the unit.

 

Fine if all the detrius is flat on the bottom, but I'm afraid that often isn't the case.
Ask anyone who has ended up with a roll of wire, or the remains of a mattress wrapped around the prop and rudder.

Link to comment
Share on other sites

6 hours ago, cuthound said:

 

I always make a point of reversing into and lightly touching boats moored in winding holes. If they come out shouting at me, it gives me an opportunity to tell them the error of their ways.

 

 If no one tells them what their doing wrong it is unlikely that they will change their ways.

" I've parked here for lunch in this layby and don't see why I have to get out!!!! "

Edited by Ex Brummie
Link to comment
Share on other sites

18 hours ago, Graham Davis said:

Ask anyone who has ended up with a roll of wire, or the remains of a mattress wrapped around the prop and rudder.

I did..... Me!!! , and We concluded in the scheme of things that fitting or not fitting an articulated rudder would make no difference to the chance pick up of canal bed objects around the stern gear.

 

Link to comment
Share on other sites

On 23/11/2018 at 23:00, Graham Davis said:

Fine if all the detrius is flat on the bottom, but I'm afraid that often isn't the case.
Ask anyone who has ended up with a roll of wire, or the remains of a mattress wrapped around the prop and rudder.

Has it happened to you often? 

Link to comment
Share on other sites

5 minutes ago, Mike the Boilerman said:

 

I guess its zig-zagging along the sky because the helm is at the front, when it is best placed at the back as any fule kno. 

 

 

Tail wag, caused by faulty avionics, fly by wire computer dodgy.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.