Servo pendulum windvane question

[Hermit Scott]

This question is about a servo-pendulum that is actuated by a wind paddle and turns the wheel at the helm to correct back onto course.
I have been looking on youtube, but I don't see any videos that show how the pendulum moves in relation to the boat's rudder.
In my minds eye it seems that the pendulum can swing either way to generate the force necessary to pull the ropes and turn the wheel, but which way do they swing relative to the way the rudder is moving?
If the wheel is turning to port, the trailing edge of the rudder is swinging to port, which way is the servo pendulum swinging? To port, or starboard?

---Is this the way they work; the wind paddle gets blown to one side, it twists the servo rudder post causing it to swing to one side from the unbalanced force on the water rushing by. The swinging servo rudder pulls on a rope connected to a spool on the wheel and corrects the boat back onto course, bringing the wind paddle back into the center postion, twisting the servo rudder post the other way causing it to swing back toward center.

 

[rpwillia]

There was a post ...

I believe it was related to Jessica's trip as she has one, and a link to a manufacturer (I think Stu posted it) that showed their servo pendulum product. Essentially the wind vane is connected via cables to your wheel (can't remember if they are reversed or not). The cables are run into the cockpit and attach to your wheel on a ring (usually larger than your Autopilot attachment on the wheel). Wind works on wind vane, turns wheel slightly which turns rudder slightly as well as the water part of the wind vane (reinforcing the force) until the wind vane gets equilibrium (same amount of wind on each side). The mfr site that Stu(?) posted explained it really well. Pretty neat system.

 

[Sailm8]

Fleming self streering

http://www.flemingselfsteer.com/

 

[Joe]

I think you have it exactly correct, Hermit.

 

[Hermit Scott]

If the wheel is turning to port, the trailing edge of the rudder is swinging to port, which way is the servo pendulum swinging? To port, or starboard?

 

[Joe]

If the wheel is turning to port, the trailing edge of the rudder is swinging to port, which way is the servo pendulum swinging? To port, or starboard?

On a tiller it would be set to pull the tiller in the opposite direction as the swing, meaning that the boat will steer in the same direction the pendulum swings. The servo swings to port, the boat steers to port, etc.. But, heck... I don't think it makes a whole lot of difference as long as the thing stays in the water. Hook your wheel adapter up accordingly. Here's one you could probably build yourself:
http://www.flemingselfsteer.com/products/wheel-adapter/

Additonal comment: Hermit, I am going to encourage you to search for more visuals of how the servo pendulum works. There are hundreds of examples on YouTube. I also ask you to go to Ask.com and query "how does a self steering mechanism work" That's what I did and there were many, many results... Here's one that's really affordable and has a bunch of video... http://www.south-atlantic.com.ar/wind_vane_self_steering/page1.html?gclid=CJSR66OfgKACFSgtawodv24blw

 

[Hermit Scott]

On a tiller it would be set to pull the tiller in the opposite direction as the swing, meaning that the boat will steer in the same direction the pendulum swings. The servo swings to port, the boat steers to port, etc. Hook your wheel adapter up accordingly. Here's one you could probably build yourself:
http://www.flemingselfsteer.com/products/wheel-adapter/

I am going to try the jib sheet to wheel self steering, and a spool for the wheel is required for that. So I built this one. I have to install the profurl c320 I just bought first. I have no furler or any way to raise a headsail yet.
I was wondering what it would take to build a windvane. There is no doubt I could build one, there is much doubt whether it would work correctly though.

 

[Joe]

I am going to try the jib sheet to wheel self steering, and a spool for the wheel is required for that. So I built this one. I have to install the profurl c320 I just bought first. I have no furler or any way to raise a headsail yet.
I was wondering what it would take to build a windvane. There is no doubt I could build one, there is much doubt whether it would work correctly though.

A much more economical and practical solution at this stage, but are you saying you have no jib halyards? That should be your first priority. You can't sail without it.

 

[jibes138]

Sailing a catalina 30 under mainsail alone is like driving a Viper with a golf cart engine. You won't believe how much more power you'll have and enjoyment once you get your headsail up. What do you have for headsails with the boat? A lot of boats came standard with a 110 percent jib and most owners would then buy a 150% or 130% genoa to use in lighter airs. Have you checked out the condition of your headsails? Is your boat the tall rig or the standard rig? Did your furler come with a double headsail groove in the foil or just a single groove?

 

[sailingdog]

You might want to look at the Mr. Vee website, which has plans for a fairly basic servo pendulum windvane design.

One issue that crops up with wheel steering is how many turns, lock-to-lock, the wheel requires. If it takes too many, setting up a windvane becomes problematic.

I am going to try the jib sheet to wheel self steering, and a spool for the wheel is required for that. So I built this one. I have to install the profurl c320 I just bought first. I have no furler or any way to raise a headsail yet.
I was wondering what it would take to build a windvane. There is no doubt I could build one, there is much doubt whether it would work correctly though.

 

[Hermit Scott]

Sailing a catalina 30 under mainsail alone is like driving a Viper with a golf cart engine. You won't believe how much more power you'll have and enjoyment once you get your headsail up. What do you have for headsails with the boat? A lot of boats came standard with a 110 percent jib and most owners would then buy a 150% or 130% genoa to use in lighter airs. Have you checked out the condition of your headsails? Is your boat the tall rig or the standard rig? Did your furler come with a double headsail groove in the foil or just a single groove?

In a good blow on a reach, I can get about 5 knots out of her. Usually it's around 3. Yes, with main alone she is a turd.
I have the original 110, or 100. I don't know what it is yet because they have luff tape and I had no furler at all. I replaced the headstay a year or so ago, and the furler was corroded onto it. I had to scrap it, despite my best efforts to save it.
The POs took the sails off while they let her sit so they are in fair condition. I have a 150 that is in very good condition. I keep them in my apartment rolled up.
My boat is a standard rig, but apparently tall for a standard sized 30 boat, none of the furlers in the 30 foot boat range were long enough.
The furler does come with a double head sail groove, a removable drum and a prefeeder to use the foil for racing.

Joe-I replaced one halyad a couple of months ago with 7/16" samson rope. The other is a wire to rope halyard, which I don't like but it will work for now.
What I was saying about not being able to raise a headsail is I don't have a furler or any hanked on sails, and both the headsails I have have luff tape on them.

 

[Hermit Scott]

You might want to look at the Mr. Vee website, which has plans for a fairly basic servo pendulum windvane design.

One issue that crops up with wheel steering is how many turns, lock-to-lock, the wheel requires. If it takes too many, setting up a windvane becomes problematic.

I saw that design on youtube, while trying to figure out how windvanes work. I will subscribe and check that out to see how he did it.
I was wondering how many turns my wheel takes. On the spool I made, I get 1.25 turns in either direction. The effective diameter of the spool is 14.25". Most self steering systems must generate ALOT of force because their wheel spools are like 6" OD. Also they appear to get 2 or 3 turns in either direction. I wouldn't think a self steering system would need that many turns. While they are working they seems to only need 5 or 10 degrees.

 

[Joe]

Hermit... I understand now.... Lot of work. I'll be happy to hear your report once you get the headsail operating. It will make the boat so much easier to handle, not to mention the speed. Truth is, this will probably be your largest expense for a while so I hope you start enjoying the boat once it's fully rigged. Then you'll be able to balance the boat so it will practically sail itself.

Oh, btw, there are two Catalina 30 rig configurations that are designated as the STANDARD rig and the TALL rig. The tall rig has a short bowsprit, taller mast, shorter boom... creating a higher aspect mainsail than the standard rig. The designation has nothing to do with other boat makers' 30 foot designs.

 

[Bill Roosa]

wind vane steering considerations

If you balance your sail plan the rudder is very easy to move. All wind vane systems and any other self steering require you to balance the sail plan to get good performance. In fact once you get the boat balanced you can do all kinds of stuff like lock the tiller and steer the boat with the traveler or jib sheet.

 

[okawbow]

"What I was saying about not being able to raise a headsail is I don't have a furler or any hanked on sails, and both the headsails I have have luff tape on them. "

For a few dollars, you could get one of your head sails modified to use as a hank-on. I have a 150 genoa, that has luff tape on it, that was modified by adding snaps on straps, and a single plastic hank on top. Any sailmaker could do the job.

As far as the servo-pendulum windvane..I'm making one now. The way it works, is when the wind vane is set on edge towards the wind, as the boat is on course; The oar, or little rudder, is centered. If the boat drifts off course, the flat of the vane is exposed to the wind, and therefore blown over a little. This action either lifts, or depresses a pushrod, depending on whether the boat is drifting off course to the left or right. The action of the pushrod translates through gears or levers, a right or left turn of the oar. When the oar turns; water pressure (when the boat has forward motion,)pushes the oar and the pendulum assembly forcefully to one side. A pair of lines attached to the pendulum, goes through a series of blocks to the tiller or wheel. Some systems require these lines to be crossed, in order to turn the boat in the proper direction.

 

[Hermit Scott]

I tried to pull the wheel off to bring it back to the shop to mount the spool perfectly concentric, but the wheel requires a puller t pop it off of the taper.
You who have your boat out back of your house are very lucky/smart people.

Okabow, for zero dollars more I can install the furler and use these luff taped sails

 

[Jeff B.]

Hi Scott,
Here's a video of a servopendulum in action, with a top down look at how the rudder/oar reacts in the water. It looks like if the trailing edge goes left, the rudder swings right and therefore the swing-arm will go left. Following the ropes, this would pull a tiller to the right and therefore turn your boat left. If you have a wheel, I think you need to cross the ropes at the rig's crosstree.

http://www.youtube.com/watch?v=VIGqNJiS7yA

I just started building my own self-steering rig this weekend based on Walt Murray's online plans (a 20-20B), plus a little improvisation. All the main components are pieced together with the exception of the rod/crankshaft assembly inside the mast, and it's been pretty straightforward so far. I can't vouch for its accuracy once completed, but that's more a reflection on my dubious craftsmanship.

Good luck with yours. Post pics when you get it together.
Jeff


Other helpful links:
http://www.mindspring.com/~waltmur/Self-Steering/
http://www.windsteuerung.de/images/alkema/RHM-USD.pdf
http://www.windautopilot.de/images/alkema/USD-vane.pdf