SySunday

Ultralight windvane selfsteer project

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I’m in the process of making an ultralight windvane selfsteer. My boat is very light (1200kg) and I don’t want a heavy device hanging there. I’ve had windvane steering gear on my 3 previous boats, so I somewhat know what is going on in these. The design brief is simple: max 2500gr, some €400 material.

the vanehead will be 3dprinted, placed on a carbon tube. Transmission of movement is by (expensive stainless) bicycle cables. Windvane will be foam-carbon, same as trimtab rudder.

 

ED200847-B86D-4E3A-8690-6CDD9668550E.jpeg

46C8CC09-E6E2-4D30-B9F7-9970BAD10A65.jpeg

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You might be able to play with the shape of the rudder  leading edge

Also  seek ways  to reduce any friction in the system 

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16 minutes ago, tane said:

no rudder feedback that I see...will oversteer heavily!

Where do you see No rudder feedback? My sketch does not give the details of that yet..

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No Rasp, that’s Grinde’s little sister, Marsvin. Same designer Peter Bruun

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You're using bicycle cables because you need both push and pull? (Just trying to understand setup - not familiar with self-steering.)

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I just see that the trimtab is actuated by two cables the covers of which semm to be attached to the rudderhead...

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windvane-self-steering-trim-tab-gear.jpgthis has a "rudderfeedback". when the vane has not moved & the rudder is put over (boat stationary) then the trimtab has to be deflected so it wants to turn the rudder back to center.

this07.gif will oversteer heavily (& if the principle is the same the horizontal-axis of the windvane makes no difference)

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For a cheaper but still very light windvane, you might copy the Monitor windvane. They use corrugated plastic - the same sort of material used for real estate signs on houses for sale in North America. Get it from your local sign making shop. Very cheap. Drill overize holes on one side, and plug with epoxy for fasteners.

Like this:

https://www.canadiandisplay.ca/10-Pieces-Blank-Corrugated-Plastic-Sheets-White-p/BCP04W-18X24X10P.htm?gclid=EAIaIQobChMI4bLSof6l2QIVRGV-Ch0ngAJAEAQYASABEgLZ1fD_BwE

 

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I loved Per Bruun's boats.  They have done some excellent passages.  Grinde, Spaekhugger and the big one Kaskelot.  I did the 1975 Fastnet on the prototype Grinde.  Splendid boat, and very well-balanced.

Good luck.  You'll have fun!

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You probably want to keep the cables in a straight line, to reduce friction.

spray on silicone lubricant would help as well.

have you seen the rudder head pendulum vanes on the old Walt sites on Mr Vane?

Interested in seeing if the cables work....

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On 2/15/2018 at 3:31 AM, Zonker said:

For a cheaper but still very light windvane, you might copy the Monitor windvane. They use corrugated plastic - the same sort of material used for real estate signs on houses for sale in North America. Get it from your local sign making shop. Very cheap. Drill overize holes on one side, and plug with epoxy for fasteners.

Like this:

https://www.canadiandisplay.ca/10-Pieces-Blank-Corrugated-Plastic-Sheets-White-p/BCP04W-18X24X10P.htm?gclid=EAIaIQobChMI4bLSof6l2QIVRGV-Ch0ngAJAEAQYASABEgLZ1fD_BwE

 

Yer, I use that stuff for mine. The 6mm stuff is the go. The stuff is so light and cheap I carry a quiver of different sized vanes for varying wind strengths.

 

As Tane has pointed out the feedback is the key.

How are you achieving this? I'm all ears.

 

2.5KG seems a little optimistic, I built mine with a Carbon shaft (servo Pendulum) and the vane counterweight was most of that weight.:D

 

 

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"... the feedback is the key."

a whole lifetime ago I tried it without - the zigzags were WILD! (& that was a 34' Wharram cat, not really a skittish beast)

try no two with feedback (of course 5 times as complicated to make) worked very well!

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You might want to check out the Mr Vee Vanes https://windvaneselfsteering.com/ which seem to be just about the lightest self steering gears around. Their Mr Vane weighs in at 6.5 kgs and their Y&B model at 10kgs. They also happen to be a quite a bit cheaper than anything else out there.

My main attraction to the design is the USD vane which is both lighter and more sensitive.

USD.jpg

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On 13.2.2018 at 3:07 PM, SySunday said:

Where do you see No rudder feedback? My sketch does not give the details of that yet..

how can you have feedback with 2 pull cables? you could use one push/pull-cable with the cover fixed on the hull & a little "trimtab-tiller" pointing forward that the inner cable goes to

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i've had the mrVee Y@B on my boat, didn't get it to work. I'm in contact with Jan Alkema (shown in picture above) and he advised me on how to get the proper rudder feedback.

That will be no problem. Weight of 2500 seems still very well possible: I'll keep this topic informed.

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Nah, wish I could pay that, in titanium!... ;-)

3 parts are polyamide PA12, smallest part is Glass filled PA12. Printed in 3D SLS machine.

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The printed parts look great! I got some quotes for laser sintered titanium mast rotator ball and socket and was surprised the cost was pretty reasonable. Nice thing is that they infused the sintered Ti with some sort of Oilite bronze and cook that in to fill in the interstitial spaces between the Ti granules and for the mast rotation it is all self lubricating and very strong. Now I can see now much of the non-stressed volume and get the weight/cost down further without affecting strength. 

    Keep up the great work and keep sharing here!

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25 minutes ago, glenc0 said:

like the concept-keep working on it

Concept hell! The guy is actually well on his way to having the prototype built. Let keep encouraging though. Thanks for the link to the 3d viewer. I didn't see a 'Save as Rhino .3dm' file though. 

    I just signed up for an account at that machineresearch viewer app, thanks for the tip.

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looks very well planned! carbon tube a smart feature (not so sure abt the transmission of vanemovement by wires...the little plastic clip-on-balljoints on Atoms & Navik gears had very little friction, were very light & lastet - to my big surprise! - 2 entire rtws [& were still good!])

what's the thin rod going down from the low end of the vaneaxis going to be for btw?

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44 minutes ago, tane said:

 

what's the thin rod going down from the low end of the vaneaxis going to be for btw?

That is for a counterweight / elastic combination

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Its looking great.

I'm sure you have already considered the effect of the buoyancy contained in the  rudder trim tab.

Looking forward to seeing the finished product. 

 

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buoyancy of trimtab: I have thought about giving it positive buoyancy and have a conical bearing at its upper part.

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boyancy would counter weatherhelm at heel - sounds like a good point (alternatively a little  weight on trimtabtiller.

low-friction those Noko-cable, pushrod be lower still...

btw: how's your feedback going to work?

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On 15/02/2018 at 5:01 AM, Zonker said:

For a cheaper but still very light windvane, you might copy the Monitor windvane. They use corrugated plastic - the same sort of material used for real estate signs on houses for sale in North America. Get it from your local sign making shop. Very cheap. Drill overize holes on one side, and plug with epoxy for fasteners.

Like this:

https://www.canadiandisplay.ca/10-Pieces-Blank-Corrugated-Plastic-Sheets-White-p/BCP04W-18X24X10P.htm?gclid=EAIaIQobChMI4bLSof6l2QIVRGV-Ch0ngAJAEAQYASABEgLZ1fD_BwE

 

I destroyed a couple of those twinwall polycarbonate ones as supplied with the flemings. About 30 kn apparent seems like the limit (at least for a tall vane) before the thing starts flapping like a flag, fatigue at the pinchpoint aroumd the clamp then make short work of it. 

Prehaps a bit of carbon tube inside the bottom of the polycarbonate vane might help.

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On 27/02/2018 at 3:49 AM, SySunday said:

Cables and titanium spanner + handle

CD81B125-415B-44A2-8C42-0FB09D029328.jpe

 

Awesome work. Looks perfect for my 23 footer. 

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Wires work.  I've used them, but "pull only"...not push. So you need two  Use the wires to transmit the movement of the vane to a little tiller, which activates the trimtab..  Jan Alkema used wires on his RHVM vane  Get stainless steel bicycle brake cables. If you need housing there is also bicycle brake housing which is wound stainless, with a vinyl covering over it. Inside is a teflon sleeve, the length of the house. It's very corrosion resistant and almost friction-free. You'll need no more than a few feet of it, it'll be < $20.

Jan Alkema passed away maybe 18 months ago.  He saw the Mister Vee vane, but he's not the guy who owns the company.

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Is there a conclusion as to whether sleeved cables are lower in friction than rope and pulleys? I would naively have thought that dyneema through LFRs would have been the ultimate in robustness as it can't clog and won't decay with time.

P.S. I love this windvane, it's absolutely awesome.

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The old scanmar autohelm unit uses a very similar system, with bike cable and gets away with no feedback mechanism. I guess since it is an auxiliary system the locked main rudder supplies the course damping to some extent. Having a robust way to lock rhe trimtab for manervering or motoring has been a problem for me with other trim tab systems. Ideally the whole trimtab could be retracted somehow.  

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I think bike cables are very low friction - and are light and cheap. So why not use them?

Locking the tab locks the rudder so a simple pin through the base or latch would do the trick. Easy enough to add (or print another head)

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Thanks for the comments. And: Jan Alkema is alive, I spoke to him 2 weeks ago and received his mail 3 days ago.

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17 minutes ago, Zonker said:

I think bike cables are very low friction - and are light and cheap. So why not use them?

Bike cables aren't made with the marine environment in mind. They might or might not withstand it very well. I'm betting @SySunday isn't the first person to use them, so there's probably a body of evidence as to how well they perform.

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heaps of salt here on the roads-bike cables doing well. those expensive nokons shouldn't be an exception. if yes: shimano is fine

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Cool. I'm intensely interested in the results of bike cables after years of exposure to marine environment. Anything which is a consumer product and still survives on a boat is awesome.

I wonder if hydraulic bike lines would also function as easily, or perhaps even better, than cables. You get the nice fact that at the low speeds you'd see in a self-steering vane, they are practically frictionless around tight bends. Of course, you might also get some real nastiness around the seals.

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even if they don't hold up years it's cheap to replace them after a year. I do so on the bike to improve shifting performance
( I think the stainless steel versions will hold up for a while, just clean them out with sweet water from time to time to get the salt out.. )

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Huh...I'd have sworn I read that he passed away.  If that's internet rumour, then I'm delighted! 

Regarding bicycle brake cables.... the loads on a self-steering control wire or pushrod are pretty low. I mean, what's exerting force on that cable is the force of the wind on the air blade. It's not even 20 pounds, even in 30 knots.  The stainless steel cables get used on mountain bikes all the time, and mtn bikes see a lot of general crap.  If stainless steel bike cables don't do it for you, you could go down to your local chandlery and purchase a few feet of their smallest 10 x 16 stainless steel wire.   The nice thing about the brake cables, or shifting cables, they'd work too, is that they have cast ends.  These ends can easily be set up to slide onto fittings attached to the wind vane.  If you use straight wire without ends, then you have to cobble some way to attach things...not that fabbing up some sort of set-screw arrangment is difficult.      If you choose to use lines, NOT running in a housing to transfer the pulling force, there's  no reason you couldn't use small, low friction blocks and small diameter dyneema. It would work fine, you just have to figure out the geometry.

And if you just HAVE to spend money to feel good, then I'm sure there's some  carbon infused wombat umbilical cord fiber  developed by the Chinese A-cup campaign that costs a thousand dollars a foot that will last forever and stretch even less than either s.s. or dyneema.  Personally, I'll spend ten bucks on a couple of s.s. wires and pack a spare set in the backup-kit box.

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BTW, I am seriously impressed by the whole 3-D printing done on this part.  Now you've got me thinking. I have access to one, a cheap one, at work.

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This is the design for the small 6cm radius quadrant to be mounted on the rudder axle. I will use a large 78mm dia ceramic bearing on which the quadrant will rotate in max plus or minus 24 degrees of angle.

D14B7221-3E23-41CA-9482-8D7DF9D575AA.jpe

FE94D885-9F37-4060-9204-1113809C3788.jpe

E12743B9-5126-4FED-8F3C-7BE0B44F74FF.jpe

BDFCFFD0-9B8A-4BEB-B943-9DF6265B0128.jpe

Together it will look like this:

5D628C8C-1CF3-4E23-BF73-86F816F1C91B.png

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All Made exclusively on iPad, with Shapr3D: https://shapr3d.com/

i never learned anything about 3d design software, but, with quite a lot of time, trial and error, that Shapr3D allows me to make these designs now.

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Dang! Just checked out that link, thanks. Almost makes me want to go get an IPad Pro. I see that it uses the ParaSolid modeling kernel which is what Solidworks is based on and explains the look which I recognize. Parametric based which is what my design software Rhino3D lacks. Only thing I saw that I didn't particularly like was that it is only subscription.

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I use the iPad pro (12.9) also as my plotter.

just recently Shapr3D increased their subscription rate. As an early adapter I still pay their starting subscription. 

Btw: three workspaces are free for testing.

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3 hours ago, SySunday said:

All Made exclusively on iPad, with Shapr3D: https://shapr3d.com/

i never learned anything about 3d design software, but, with quite a lot of time, trial and error, that Shapr3D allows me to make these designs now.

As a mechanical engineer (learned SolidWorks back in the 90s), that you just did that beautiful and professional assembly on an iPad blows my mind.

Next thing I know, we'll be doing symbolic math on iPhones. :blink:

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Hi there,looking good so far ☺

Built a trim tab to the dimensions recommended by John S Letcher jr in his book 'Self steering for sailing craft'.

This is on a 25ft boat 2000kg and has been dragged around for far too long while i work out the control system so I might be very interested in buying a set of your printed parts if you were to run off another set.

A few questions if I may;

The materials used(not the carbon) are they repairable with epoxy if damaged or is it more like a poly plastic?

How brittle is it as a material?

Any bearing material in the vane axis?

I must be thick but your drawing of the rudder fitting looks like it just provides differential (gearing) from the vane to the tab and not feedback,more details?

Take care

Rob

tmp_7070-20171028_095927-1-1-1850984193.jpg

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the blue wheel is like mounted-on-the-boat, not on the rudder (its exactly above the rudder-axis). I too thought he wouldn't have feedback, but in post 35 u see that he does

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16 hours ago, triciarob said:

A few questions if I may;

The materials used(not the carbon) are they repairable with epoxy if damaged or is it more like a poly plastic?

==> I think not that easy. All m printed materials is “SLS printed PA12”, Some of the parts are glass filled PA12, here abrasion by the stainless cables may come in to play. PA12 is  one of the stronger materials, only to be improved with carbon fiber filled PA, which is quite expensive and not that much stronger.

How brittle is it as a material?

==> not very brittle, actually in my experience until now very strong. Still I use at least some 5mm thickness in critical places.

Any bearing material in the vane axis?

==> yes; two 608 ceramic bearings as in pictures below.

7C6DF8D6-69C2-4D39-8ED1-F0F08628E7F1.png

036B7DE6-C0C5-440A-929B-5CA8196839F9.png

 

I must be thick but your drawing of the rudder fitting looks like it just provides differential (gearing) from the vane to the tab and not feedback,more details?

==> i never really understood the concept of “rudder feedback”. Jan Alkema, to me an important source on this theory, likes to call it “ rudder counter coupling”, at least in Dutch.. THAT I think to understand and this is illustrated in my post:

 

 

 

 

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as written in my previous posts: "rudder feedback" is the type of servo (-pendulum or -tab) actuation, that reduces the angle of attack of tab/pendulum as the rudder  responds to the tab-deflection/pendulum swing. with boat stationary it is very easy to see if the linkag(es) has/have feedback or not: windvane held centered the rudder is deflected (by wheel or tiller). if tab or pendulum deflects in a way that with waterflow from the moving boat they would exert a force on the rudder that pushes same to a centered position - then the linkages have feedback.

e.g. on a pendulum system it is indispensible, that as the pendulum deflects to the side it's angle of attack to the waterflow is reduced, otherwise it would slam to it's stop even with small  deflections of the windvane from the centered position.

on a trimtab-system no feedback would mean that the angle bvetween rudder & tab stays the same as the rudder swings to the side so even small angles of the tab would force the rudder all the way over. A typical trimtab system without feed back would be vertikal-axis vane on the same axis as the tab.: this would make the boat yaw wildly around the intended course

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On 19/03/2018 at 3:57 AM, triciarob said:

Hi there,looking good so far ☺

Built a trim tab to the dimensions recommended by John S Letcher jr in his book 'Self steering for sailing craft'.

This is on a 25ft boat 2000kg and has been dragged around for far too long while i work out the control system so I might be very interested in buying a set of your printed parts if you were to run off another set.

A few questions if I may;

The materials used(not the carbon) are they repairable with epoxy if damaged or is it more like a poly plastic?

How brittle is it as a material?

Any bearing material in the vane axis?

I must be thick but your drawing of the rudder fitting looks like it just provides differential (gearing) from the vane to the tab and not feedback,more details?

Take care

Rob

tmp_7070-20171028_095927-1-1-1850984193.jpg

Sadler 25?

I'd recognise that prone to cracking skeg anywhere! 

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Well spotted!

Had to fix it a couple of years back using s/s sub-frame after the original frame rotted :wacko:

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Today I finished 2 windvanes: one foam-cored Carbon of 60cm and one polycarbonate of 70cm. Surprisingly the carbon weighs 275 and the PA 325grms. Finished in fluo paint and decorated with glow in the dark strips:

1FD3FB2C-C196-46F7-B5A6-F527601A0AA8.jpe

i also finished the trimtab: foam cored with carbon, now in anti fouling and to be polished:

ACF11797-F026-4603-AEA4-616467B2EC51.jpe

 

Now that I have almost finished all components and I can calculate the finished weight: this will be below 2000gr, some 500gr less than the “design brief”

 

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6 hours ago, tane said:

is there a particular reason the trimtab's leading edge is concave?

Look at the shape of the rudder in the first post.

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On 4/9/2018 at 3:39 AM, SySunday said:

 

i

Now that I have almost finished all components and I can calculate the finished weight: this will be below 2000gr, some 500gr less than the “design brief”

 

Nice, now is it strong enough to be fit for purpose and does it steer well enough to be a viable solution".

Time will tell.

you may need to keep your dingy well clear of the trim tab :)

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Received a box full of 3D printed parts:

7A5592F7-7824-4D13-8D5D-82E310EC19A7.jpe

To be installed on/around the rudderhead:

8844E36C-ADB2-4A75-BCA9-D50F3A17FF43.jpe

And on the rudder:

FA9E04C2-CC90-4C9A-A53E-5F2D5DC2B13D.jpe

 

 

 

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Looking good! what kind of bracket are you going to use at the bottom of the tab?

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On 13-4-2018 at 9:23 PM, SySunday said:

first trial: 

 

 

 

 

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On 5/5/2018 at 2:32 AM, SySunday said:

 

Looks awesome, any more updates?

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No other than just some more in-harbour tests, I had to reposition my solarpanel and the way it is adjusted, and so many more small details. Next week first sailing!

 

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Looks like it works nicely, no sign of oversteer. Whats the vane made from?

I have to make a new lightweight vane for my windpilot copy. 

 

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