Autohelm on a canoe stern

[DownWest]

My

Think the extension bracket is far simpler .... and if I remember correctly AH .. later Raymarine provided something to do this.

If you are going to fabricate an extra piece to rudder stock - to move AH forward ... surely that's more work than a simple alloy bracket ??

My basic point is that the AH should be at right angles to the line 'x' from the pin to the rudder axis. So, if the the pin is off to one side of the tiller with the bracket fitted, then the AH will be at an angle to the tiller equal to the angle that is made by the line 'x'. That willl bring the mounting end of the AH forward, where there will be more space.

 

[Buck Turgidson]

My

My basic point is that the AH should be at right angles to the line 'x' from the pin to the rudder axis. So, if the the pin is off to one side of the tiller with the bracket fitted, then the AH will be at an angle to the tiller equal to the angle that is made by the line 'x'. That willl bring the mounting end of the AH forward, where there will be more space.

It made perfect sense to me! It’s the only way to stay within the width constraint.

 

[Refueler]

The angle created by a bracket off the tiller to the rudder stock makes no difference to the steering arc ...

Why ? Because the main point is to keep the AH at right angles to the tiller at midships. Whether the pin is on the tiller or xx inches to the side ... is not an issue ...

If you move the AH forward and its not at right angles to the tiller at midships .... then the rate of change of tiller / rudder per unit of AH rod change alters significantly whether rod extending or retracting.

 

[Buck Turgidson]

The angle created by a bracket off the tiller to the rudder stock makes no difference to the steering arc ...

Why ? Because the main point is to keep the AH at right angles to the tiller at midships. Whether the pin is on the tiller or xx inches to the side ... is not an issue ...

If you move the AH forward and its not at right angles to the tiller at midships .... then the rate of change of tiller / rudder per unit of AH rod change alters significantly whether rod extending or retracting.

No . The tiller is not important. You can mount an actuator at any angle you like so long as you know what a tangent is.

 

[wallacebob]

Maybe not a great photo, but I added a block on the coming to extend the arm of my autohelm and raise it to correct height for tiller. Having a transom hung rudder helped, as youneed a minimum fulcrum.

 

[Refueler]

No . The tiller is not important. You can mount an actuator at any angle you like so long as you know what a tangent is.

"The tiller is not important." ???
The Tiller is the 'arm' used to move the rudder - the angle the AH is connected to tiller is extremely important.

The only time tiller is not important is if a second 'arm' is connected to rudder for AH to operate on. But that also needs a 90 deg angle AH to the arm. In this case you can set the second arm at any angle to the rudder - but AH must still be at or near 90 deg to that arm.

 

[DownWest]

We seem to be discussing the same point. If you mount the pin on a bracket to one side of the tiller, then you have, in effect, a second 'arm' off the rudder stock, which the AH needs to be at right angles to.

 

[Refueler]

We seem to be discussing the same point. If you mount the pin on a bracket to one side of the tiller, then you have, in effect, a second 'arm' off the rudder stock, which the AH needs to be at right angles to.

You and I may be .... but 'Buck' seems to be off on a jaunt ...

The issue is to maintain the arc steps of operation either side of midships ... if not at 90 deg to tiller or second arm fitted to rudder stock - it will have unequal movement either side.

 

[DownWest]

You and I may be .... but 'Buck' isn't. Unless his description has been misunderstood ...

Buck's comment about the tangent is correct. The AH needs to be at a tangent to the arc of the pin at center rudder

 

[Buck Turgidson]

"The tiller is not important." ???
The Tiller is the 'arm' used to move the rudder - the angle the AH is connected to tiller is extremely important.

The only time tiller is not important is if a second 'arm' is connected to rudder for AH to operate on. But that also needs a 90 deg angle AH to the arm. In this case you can set the second arm at any angle to the rudder - but AH must still be at or near 90 deg to that arm.

DownWest gets it. As does everyone with an autopilot actuator not attached to the tiller and those few who have bracketed off a tiller for better geometry. I’m really surprised given that you make model aircraft that this is not clear to you. ?‍

 

[Refueler]

Buck's comment about the tangent is correct. The AH needs to be at a tangent to the arc of the pin at center rudder

Gor blimey Guv .... 'tangent' ???? Its very simple - forget fancy trig terms ... its to be at or near 90 degrees ... QED.

If its not 90 degrees - then rudder will not move same steps in arc per movement of AH either side ...

TBH - getting a bit fed up with this .... guy needs to solve fitting his AH so he gets good steering without having AH hanging outside gunwhale. The easiest / simplest way is to add a bracket fitted to tiller that then allows AH mid-point rod to sit on pin at 90 degrees to tiller when midships.
I've even sketched a diagram .... I find it hard to understand what is so difficult about it ????

I am sure OP now has made up his mind .... I shall be interested to read what he does ...

 

[Refueler]

DownWest gets it. As does everyone with an autopilot actuator not attached to the tiller and those few who have bracketed off a tiller for better geometry. I’m really surprised given that you make model aircraft that this is not clear to you. ?‍

Suggest you go back to OP's request ... get a protractor and some paper ... UNDERSTAND his problem ..... instead of just jumping on a bandwagon .....

The ONLY geometry is 90degree ..... Autohelm installation instructions are clear on this. The question is how to achieve this without AH hanging outside gunwhale .....

It might help if you or DW actually take a few minutes to create a simple diagram to explain 'your' version ....

 

[Buck Turgidson]

The geometry for a and b is the same. B allows the tiller pilot to be mounted at an angle to reduce width.

 

[Buck Turgidson]

Deleted

 

[stacer]

Seems like I have provoked some strong arguments on this?. Many thanks to all who have contributed, you have provided me with some very good ideas to solve what I initially thought might be insoluble. I’ll certainly post the details of my final solution and let you all know how it performs.

As a newcomer to this forum, I am truly impressed with the knowledge base here, the willingness to provide help and above all the passion expressed by some posters??

 

[DownWest]

Out of interest, what model is the boat?

 

[stacer]

The boat is a Longshore 16
This is the view of the stern minus the tiller

 

[stacer]

Out of interest, what model is the boat?

A Longshore 16 see below

 

[DownWest]

So, not dissimilar to my Whilley Tern, though there is no way I would be fitting an AH I don't even cleat the mainsheet!

Here is the designer in one, same rig, his reefed a bit...

 

[stacer]

So, not dissimilar to my Whilley Tern, though there is no way I would be fitting an AH I don't even cleat the mainsheet!View attachment 144212
Here is the designer in one, same rig, his reefed a bit.

Looks like it although mine has a small cabin unlike my last, a Character Boats Whammel which was an open boat. Although an AH isn’t essential, sailing here around the islands of the Firth of Clyde can be quite cold and wet even in the summer and the ability to go below for a few minutes to make coffee or just for shelter would be welcome.