I am making a windvane

[Alan H]

If in fact the spring clamp doesn't work, I have another option for course setting....

[Alan H]

[Small boats rock]

Donuts united!

[Alan H]

Donuts united!

They were only apart for a day...LOL!

Anyway, I am getting close! I went to the local metal warehouse yesterday to get some aluminum bits, but they were closed. OK, so I'm saving money by making what I need out of wood, fiberglass, epoxy and PL Premium polyurethane.

Pendulum Oar tiller arms.

TillerArms.jpg

The linkage "bicycle brake" cable housings have to terminate on the oar carrier somewhere, but I realized yesterday that I can't just screw some aluminum bits to the main oar carrier shaft. Nope, the angle will be wrong, which will add friction. So I inset these blocks about 1/8th of an inch into the arms and glued 'em down with a generous quantity of PL Premium. They'll get painted to match, probably tomorrow. Believe it or not, the blue paint is all one color, the lighting just radically changes what it looks like!

CableStops.jpg

[skaraborgcraft]

Keep going. Not much to add, looking forward to a dry demonstration.

[Alan H]

Jan Alkema's boat sailing with the USD windvane and RHM pendulum oar....



Jan used light wires from a wheel, affixed to the windvane as his linkage. They went through a few blocks, and then to a small tiller on the pendulum oar. I thought about doing it just like Jan, only with light dyneema or spectra, but I've been itching to use my brake-cable-housing idea.

[Small boats rock]

and your audience is itching to know how friction free the cable housing ends up being...

[Alan H]

A little bit of paint, a little more fiberglass...some drilling, some aluminum bending, and all the last bits are on, to test in real wind to see if the wind vane will turn the oar. Maybe tomorrow, or Sunday, down at the port, I'll clamp everything to a ladder attach the cables, and we shall see!

[Alan H]

FAIL

There was a pretty good breeze in the front yard today so I set up the entire shebang, to try it out. In the video, the cables have been disconnected, and you can see that the windvane moves very well in response to maybe 5-8 knots of breeze that wafts in from various directions. I greased the gudgeons and pintles of the pendulum oar, and it's very smooth now. But when I hooked up the bicycle cables and housing....nothing moved. A few tweaks on the pendulum oar, moving it from side to side revealed that...sadly...there's a huge amount of friction in the system. It's really stiff, way, way too stiff to work.

Now, that might be improved by using less cable and housing, and a straighter "run" to the pendulum oar, but when I have this actually on the boat, I'm going to need about as much cable and housing as I have pictured, here.

SO this is a great big flop....a $40 flop, I might add, *ouch*! though Jan linked up his with steel cable, so maybe I can use the cable, at least. If not, 12 feet of 1/8th inch dyneema is about four bucks, so I'll use that.

Hmph!

[Small boats rock]

Don't give up Alan, it is not a flop, you just have to patiently work out the bugs. If you disconnect the cables from the oar, can the vane then move them freely? Maybe the cable friction is only a part of the total friction, or maybe not even much of a problem at all. If the cables do seem to be causing friction you then need to determine, is it the cable cover, or the actual cable, or the length, or a combination of all. Might take a bit of experimenting to really understand where the issues are. Take a deep breath and keep going. You've done great work so far.

[Alan H]

Oh the whole assembly is not a flop, at all! Look at that windvane respond to the little gusts blowing through my yard! That is no flop!

I took another hard look at Jan Alkema's setup and I might be thinking of making a pendulum oar that's about 2/3rds the chord and only submerged about 2 feet 4 inches instead of 3 feet. But licking the friction problem...or rather the "linkage problem" is #1. More studying of Jan's design reveals how he makes the wires work with the course setting system. The way that's set up is sort of incompatible with my design so I might be moving to a control-rod kind of system. I have some thinking to do!

I've been harboring this "bicycle brake cable" notion for many many years, so it's good to finally test it, even if it didn't work!

I'm debating about buying the PTFE tubing, and giving that a try with the weed whacker line. It's $20....probably worth the attempt.

[Rumars]

It's not worth the 20$ to try. Use Dyneema and low friction rings (or small roller bearing blocks).

[Alan H]

Rumars, I disagree. I disagree because after looking VERY hard, for quite a while at Jan's vane, I see how he gets around the problem of the changing length of the distance that the cables cover, as he changes the heading. To replicate that, I'll have to make two more large-ish pieces and a mounting bracket....all do-able of course... but it invalidates the basic design premise of my setup. The basic premise of the vane/mast won't work with Jan's essential design. I rather like the notion of the whole thing sleeving over the "mast" and I want to stick with it.

I may have to go to a central push/pull rod linkage (I can use a carbon fiber kite rod, or some old fiberglass tent poles that I have.), to a "bent rod" actuator kind of system linked to a bell crank as per Walt Muray's work, or any of several commercial systems. THAT, I might have to do.

Before that, though, I'm taking the whole thing down to the port with my 8 foot ladder, a mess of clamps, some grease and a pair of cable cutters. I will set the whole thing up in the closest geometric alignment to how it will actually be on the boat, and we'll see if changing the amount of cable housing and the amount of curvature of the cable housing, cuts the friction, substantially. It might not....or it might. We'll just see, tomorrow.

[Alan H]

PTFE tubing...

https://www.mcmaster.com/ptfe-tubing/sleeving-4/

I have some .080 diameter monofilament wee-whacker line, which I can try, but it's ~stiff~ stuff. I have some 0.1 inch as well, but it's even stiffer.

A spool of 80 pound test monofilament fishing line is six bucks and change, probably worth trying as well.

[skaraborgcraft]

I think the problem is that big loop in the cable. I used pre-stretched 5mm dacron line from a vane down to 2 turning/cheek blocks and that worked fine.

[Rumars]

If you want to stay with the bicycle cable one thing you can try is making the lever arm at the vane longer so it has more force to overcome the friction.
You can also look at the wharram windvane, that one uses line on a drum at the vane.

[Alan H]

The Mrs. wanted to go for a bike ride, at noon. So I'm just back from 2 1/2 hours of pedaling. Before we left, I readjusted the geometry, to reflect the actual setup as it will be on the boat. That took out the big loop and son of a gun, about half the friction went away. It's still too stiff to work, but this is a HUGE improvement.

[Alan H]

The Mrs. wanted to go for a bike ride, at noon. So I'm just back from 2 1/2 hours of pedaling. Before we left, I readjusted the geometry, to reflect the actual setup as it will be on the boat. That took out the big loop and son of a gun, about half the friction went away. It's still too stiff to work, but this is a HUGE improvement.

[Alan H]

The Mrs. wanted to go for a bike ride, at noon. So I'm just back from 2 1/2 hours of pedaling. Before we left, I readjusted the geometry, to reflect the actual setup as it will be on the boat. That took out the big loop and son of a gun, about half the friction went away. It's still too stiff to work, but this is a HUGE improvement.

A bigger blade is definitely on the list, skarabogcraft. I already made this one two inches shorter than Walt's design, 'cause I trimmed the top off at the wrong angle and had to recut it. I have room to add six more inches of length and a couple of width as well before the blade will bump into the lifeline.

Rumars, your comment got me thinking and in fact, I can think of a way to use cable and housing for part of the distance...about 2/3, and then terminate the cable/housing and go to dyneema through two little low friction eyes to cover the rest of the distance. Cutting the length of cable running in housing by a third is a significant reduction in friction. So in fact, you might be on to something, there!

[Rumars]

https://www.sailblogs.com/member/kaimusailing/296258
Here you can find the drawing of the wharram windvane for comparison. It has a big sheave for lenght compensation.

[Alan H]

More study of Jan Alkema's setup revealed something that I hadn't realized before. It's hard to explain but what it means is that the final turn of the control lines is centered over the axis of rotation of the rudder. THAT means that from that point..the final turn of the control lines, the distance to the pendulum oar "tiller" stays constant as the rudder moves. However, if you move that final turning point off of that axis, the distance DOES change...which is something I was trying to get around with the brake cable housings.

If I align the mast of the windvane right over the axis of rotation of the rudder, that simplifies things. It also means that today, I reduced the amount of brake cable...and brake cable housing by half. There's a transition from s.s. cable to a piece of inexpensive polypro line right now. That polypro runs through some cheap little dinghy blocks right now. I'll change that over to light dyneema, and low friction blocks if this all works out.

So I'm halfway along towards your suggestion, Rumars! This has helped with the friction issue. So has grinding the ends of the house totally flat and reaming them out to make SURE there are no burrs or protrusions to rub against the cable.

It still take more force that I'd wish to move the pendulum oar, but I might be at a point where a good breeze and a larger wind paddle could make this work.

[Alan H]

https://www.sailblogs.com/member/kaimusailing/296258
Here you can find the drawing of the wharram windvane for comparison. It has a big sheave for lenght compensation.

That's an adaption of a vane shown in Bill Belchers book. The original idea on that vane was to run the lines emanating from the vane directly to the tiller. Some other people have adapted it to run trim tabs, which I think makes much more sense. To go straight from vane to tiller would require a BIG vane blade! It could be done though...and has been done.

I see what you mean about the sheave. Jan also uses a sheave for his wires.

[skaraborgcraft]

That's an adaption of a vane shown in Bill Belchers book. The original idea on that vane was to run the lines emanating from the vane directly to the tiller. Some other people have adapted it to run trim tabs, which I think makes much more sense. To go straight from vane to tiller would require a BIG vane blade! It could be done though...and has been done.

I have built several of those, my first was the direct to tiller, which worked ok until the rudder shaft itself got hard to turn. I used the same set up with a slightly smaller vane to operate an auxillary rudder, which worked fine.

It can be quite important where things are placed to prevent too much feedback from tab to vane, or not enough.

[Small boats rock]

I'm guessing you're alluding to controlling feedback with a differential linkage?

[skaraborgcraft]

I'm guessing you're alluding to controlling feedback with a differential linkage?

The last vane i built that used control rods, had lots of various holes for adjustment with leverage and vane to tab ratios through a bell-crank. Some vane set up are more likely to produce large swings between positive and negative feedbacks, and reducing the size of the "S" the boat sails is beneficial, though my first vane was not great, the fact it freed me from the tiller was compensation enough, i got more demanding as time past......

[gypsie]

With this talk of bicycles and friction free..... in my mind .... my sons mountain bike has hydraulic brakes.
i wonder how.......

[Alan H]

Well, I took the contraption down to the Port, where there was a solid 15+ knots of wind oscillating through about 15-20 degrees. I'm sad to say, that the brake cable linkage friction almost completely prevented the system from functioning at all. It would "move"...when the blade was practically perpendicular to the wind, if you waited 10, 20 seconds for it to finally slip and GO.

Not acceptable. OK, so that's the end of experimentation with the bicycle brake cables. Now I have extra cables and housing for my bike. **eyeroll**

VanTest-Port1.jpg

VaneTest-Port2.jpg

[Alan H]

So, adding up all the bits and bobs, this "brake cable idea" is about a $50 FAIL. On the other hand, I've been nursing this idea for almost 15 years, since I attempted my first windvane in 2005 and it's good to finally know the answer!

Next idea!...PTFE tubing! I can only get it in 10 foot lengths. grrrr. As I write this, there are two, 6+ foot lengths of .080 inch diameter weed-whacker monofilament hanging from 15 pound weights in the garage, being gently "encouraged" to "forget" the tight winding they were put under in the store packaging.

[Alan H]

The last vane i built that used control rods, had lots of various holes for adjustment with leverage and vane to tab ratios through a bell-crank. Some vane set up are more likely to produce large swings between positive and negative feedbacks, and reducing the size of the "S" the boat sails is beneficial, though my first vane was not great, the fact it freed me from the tiller was compensation enough, i got more demanding as time past......

If the PTFE tubing idea doesn't work, I'll be going to a push-rod-to-bell-crank kind of system, and abandoning the RHM idea. Instead, it'll just be a plain-vanilla servo-pendulum. The USD vane itself is fantastic...super sensitive and pretty powerful. It can be adapted!

[Stiletto]

Alan, I hope you dont mind me putting this on your thread. It may be helpful to those of us like me, who arent that familiar with the ins and outs of windvane steering.

I will never need to use a self steering system, but am very interested in the principles and the engineering involved. I applaud your efforts, and your sharing your experiences with us.

[Alan H]

Alan, I hope you dont mind me putting this on your thread. It may be helpful to those of us like me, who arent that familiar with the ins and outs of windvane steering.

I will never need to use a self steering system, but am very interested in the principles and the engineering involved. I applaud your efforts, and your sharing your experiences with us.

This is actually a pretty good short summary of the various types...

http://www.faymarine.com/plansite/fa...e_yacht_pl.htm

[Small boats rock]

So, adding up all the bits and bobs, this "brake cable idea" is about a $50 FAIL. On the other hand, I've been nursing this idea for almost 15 years, since I attempted my first windvane in 2005 and it's good to finally know the answer!

Next idea!...PTFE tubing! I can only get it in 10 foot lengths. grrrr. As I write this, there are two, 6+ foot lengths of .080 inch diameter weed-whacker monofilament hanging from 15 pound weights in the garage, being gently "encouraged" to "forget" the tight winding they were put under in the store packaging.

If at first you do not succeed, parachuting is not for you. Lets be glad this is a wind vane and therefore further experimentation is still possible. Looking forward to seeing what comes next.

[Alan H]

The PTFE tubing arrived today, so I set it all up....no luck, still too much friction, and I liberally doused the inside of that tubing with Tri-Flow. It's slicker than....than......right..

so I have two options.

1. Build a rotating base, which will work for moving the vane in relation to the wind, and keep the cables, which will not be in cable housings at all, directly in line with the axis of the mast. This is basically what Jan did. It's a lot more structure and work to build. If I do t his, I ditch the entire notion of the rotation sleeve on the mast, being the course-setting mechanism....which rather sucks.

2. Give up on a cable linkage, entirely, and move to a pushrod linkage. This would probably mean abandoning the RHM idea and going to a "regular" pendulum oar. This will also require a lot more structure to be built on the boat, however, I could stay with the rotating sleeve on the mast being the course-setting mechanism.

Frustrated.....but it was worth trying anyway. I suspect that a significant amount of the binding is not in the monofilament/housing, but rather in the aluminum ends.

[Small boats rock]

Which method offers the most reuse of your work to date?

[Alan H]

I've been thinking...I reduced the cable/housing length by half, both with this strait teflon housing and with the bicycle brake cable housing, and both times it made minimal difference in the amount of friction. If the problem is the friction inside the housing, then using half the housing should reduce the friction by 50%, but it didn't.

Look here.



See how the housing is terminated?...there's no "ferrule" there, just a clamp about the housing.
I had a neighbor over and she was wiggling the oar back and forth and we discovered that when the housing slipped out of the bicycle brake cable ferrules that hold it in place, the friction skyrocketed. I wonder if the REAL issue all along has been the cables rubbing against those ferrules.

I think....before I pitch this experiment, I'm going to try a different kind of housing termination system, something more like the AutoHelm's system.