Selfsteering gear ..

[Bill Seal]

Go back to post #4. I think John Letcher was an aeronautical engineer and he discusses at length things like positive damping (negative feedback).The book is in PDF format.

[GILow]

Originally Posted by Bill Seal

Go back to post #4. I think John Letcher was an aeronautical engineer and he discusses at length things like positive damping (negative feedback).The book is in PDF format.

Yes, he was most certainly one of the better authors, from memory.

Edit, I did find him frustrating as he seemed very reluctant to follow up his complex mathematical formulas with a recommendation. So he gives the means of calculating the outcome, but not the desirable outcome.

He combines very well with Gerard Dijkstra's book, which is strong on the recommendations but light on the maths.

[El Pinguino]

Vertical vane straight down hill in 2004

Plus 2 x 24 hour spin runs with same kit south of 40*S on way to Chile on the same trip ... 3rd 24 hour run turned to porridge when head of spin blew out....

Then in 2016 on same run ( NZ-Chile) all went west or east or wherever when we fell orf a big wet bit....

[GILow]

Well, you've certainly tossed a cat among my pigeons!

I was so convinced Horizontal vane was the only way to go. I'll stop hijacking the OP's question and start a separate thread, but thank you for the post EP.

As for the photos... well there's your poster boys for laid back sailing. Not sure I like the look of that sea state though. I may be a bit of a wimp.

[Hesti]

Thanks for the input, Gentlemen!

Regarding the boat - we are looking at boats at the moment around 26 ... 30 feet, single hull, fin keel or bilge keels, draft between 1 and 1,3 mtrs. So, no final answer yet on this point. Most of the ones on our list have a through hull rudder assembly and not a transom hung rudder. So, trim taps attached to the rudder may not work because the rudder may be under the hull with no easy way to link up to the tab.

Reason for asking now already - we want to cast of in first half of spring and time is flying.

I will have a good look at the pdf book, thanks for the link!

[thomm225]

Webb Chiles Sheet to tiller method.....

https://www.cruisingworld.com/simple-self-steering

[gmakhs]

Originally Posted by Hesti

Thanks for the input, Gentlemen!

Regarding the boat - we are looking at boats at the moment around 26 ... 30 feet, single hull, fin keel or bilge keels, draft between 1 and 1,3 mtrs. So, no final answer yet on this point. Most of the ones on our list have a through hull rudder assembly and not a transom hung rudder. So, trim taps attached to the rudder may not work because the rudder may be under the hull with no easy way to link up to the tab.

Reason for asking now already - we want to cast of in first half of spring and time is flying.

I will have a good look at the pdf book, thanks for the link!

Why not add a seccond transform hugging rudder ? And then a trim tab to it ? The construction of the rudder is not difficult can be a fiberglass foam or fiberglass balsa or fiberglass plywood sandwich, then the trim tab can be made just from fiber glass .
You can hug them in the transform and have an emergency rudder and autopilot .
If you go with this option you need to reinforce the transform by making a T with foam or balsa sandwich .
All them easy to do and cost less than 1000 in material .
Plywood for all might cost you 20 euro
Fiberglass resin and mat with gellcoat let's say 100 euro
Fittings another 200 (if you pay for the welding )
Easy project and you will learn a lot .

[El Pinguino]

Originally Posted by Hesti

Thanks for the input, Gentlemen!

Regarding the boat - we are looking at boats at the moment around 26 ... 30 feet, single hull, fin keel or bilge keels, draft between 1 and 1,3 mtrs. So, no final answer yet on this point. Most of the ones on our list have a through hull rudder assembly and not a transom hung rudder. So, trim taps attached to the rudder may not work because the rudder may be under the hull with no easy way to link up to the tab.

Reason for asking now already - we want to cast of in first half of spring and time is flying.

I will have a good look at the pdf book, thanks for the link!

It would be quite a simple matter to construct and fit a 'trim tab on aux rudder' to a boat of the size that you are considering...

You could even use the ratio of sizes ( rudder/aux/tab) that can be seen in my photos above .... then just experiment with the size of the vane.....

The tube within a tube business is actually quite simple... main tube is a strength member and holds everything on to the boat... it has bushes top and bottom that support the tube that transfers signal from vane to tab.... vane itself is constructed with solid bar vertical axis the lower end ( about 18" long ) of which simply drops into the 'signal transfer tube' ... the worm drive and geared wheel which bring it all together are the only vaguely complicated bits.... oh... and the bungee....

[GILow]

You can eliminate the gear wheel bit by using Bowden cables. Jim and Ann has great success with their diy model using this system.

[El Pinguino]

Originally Posted by GILow

You can eliminate the gear wheel bit by using Bowden cables. Jim and Ann has great success with their diy model using this system.

Ah yes.... but is it infinitely adjustable?.... one turn of the worm drive on mine = 4* course alteration...

[Snowpetrel]

Originally Posted by El Pinguino

I have a custom made trim tab on aux rudder.... has done a lot of ocean miles....

When I had it made 17 or so years ago $$$$$ were an issue... otherwise I would have bought a Hydrovane or a Cap Horn... the latter being a truly elegant bit of kit.

When in use the helm is lashed and and the only bits of string involved are one light line to engage / disengage it ( this acts against a bit of bungee that holds it in gear ) and two damping lines to restrict the aux rudder to +/- 5* or less... sail trim is everything with any SS.

Photos should explain all... the only bit you can't really see is the tube within a tube that transfers rotary from the vane at the top and converts it to push/pull at the bottom where it is sent to the trim tab.

Yvette did a fine job of building that vane. I sailed with the same system on love of Gaia. It worked very well in all conditions on a big powerful boat, though we were both slightly worried about the strength of the plywood rudder.

[GILow]

Originally Posted by El Pinguino

Ah yes.... but is it infinitely adjustable?.... one turn of the worm drive on mine = 4* course alteration...

Stop it. You are turning me on...

No... hang on... I mean you are turning me to Port. That’s it port.

[JPA Cate]

Originally Posted by El Pinguino

Ah yes.... but is it infinitely adjustable?.... one turn of the worm drive on mine = 4* course alteration...

Ahem, El Pinguino, Infinitely adjustable, more than so....it could even be set to sail by the lee, DDW. Not that we would trust it to do that in a seaway, you understand, but for maintaining course and speed, when the other guy had to gybe out and back, well, we got there first, and drinks were on our boat! Happy memories.

However, it would not steer us motoring. Used a small tiller pilot for that.

Ann

[El Pinguino]

Originally Posted by JPA Cate

Ahem, El Pinguino, Infinitely adjustable, more than so....it could even be set to sail by the lee, DDW. Not that we would trust it to do that in a seaway, you understand, but for maintaining course and speed, when the other guy had to gybe out and back, well, we got there first, and drinks were on our boat! Happy memories.

However, it would not steer us motoring. Used a small tiller pilot for that.

Ann

Got any pichas? or a diagram of how it was set up... for the OP?

[JPA Cate]

Originally Posted by El Pinguino

Got any pichas? or a diagram of how it was set up... for the OP?

I wish we did! I remember when it snapped off, after or during the knockdown that bashed up our dodger, and we retrieved the top part of it. We retrieved the top part of it, and it sure took up a lot of room in the cockpit, but we were not focussed on photo documentation just then. Sure wrecked our trip to New Caledonia, that plus the later on dis-masting. Not our greatest hour, for sure.

Ann