Calming my windvane down....

[Driftingby]

I have a secondhand windvane (Sea Feather) that I have fitted to my Sadler 25 as I sail alone mostly and would like to sail all day without having to steer all the time.

It all seems to work, apart from the fact that when connected up to the tiller, the boat swings in a 30-40 degree arc from side to side. Have I got part of the installation wrong (position of attachment to the tiller springs to mind), is there something wrong with the unit (stiff bearings) or is the boat not actually as well balanced as I think?

Everytime I try I get the same effect, so it's not just the conditions I am trying it in. I really would like to get this working effectively as I feel it would open up another dimension to my sailing. All ideas, especially from those who use windvanes gratefully received.

Chris

 

[Pye_End]

That's quite a big arc. Was this in a steady breeze, or more gusty?
I would start by watching it very carefully - ie is the vane dropping down immediately when off course? If the vane is dropping down, is the leg moving side to side, and if so is the tiller moving? It should all be an immediate motion - ie no delay that you might see in an electronic pilot. If the tiller is moving, but the boat is still going off course then it sounds like sail balance. Is there slack in the control lines? Where in the tiller have you set the control lines?
Re. stiffness in the mechanism - it is probably easier to tell when up on the side - with the vane on and the leg down you should be able to jab the vane and the leg with your finger and see if it is all nicely pendulous, or if it doesn't return to the original position.
Which version have you got? Photo would help. There may well be a couple of places that need oil or grease - do you have a copy of the service schedule?
There are a couple of things you can do to make the arrangement more or less sensitive eg move the counter weight, or put a little more weight on the vane when the wind is light (eg pegs).

 

[Sandy]

It might be worth contacting the original manufacture

Sea Feather Wind Vane Self Steering | Dartmouth, South Devon

 

[Driftingby]

Thanks Pye End, having slept on it, I suspect it's most likely to be a stiff mechanism, sadly I don't have a copy of the service schedule - the only advice I have had from Sea Feather was to use 3 in 1 regulalrly.
I may also try temporarily moving the tiller connection point at the weekend to see if that makes a diffference, again, not having any documentation I just used the electric autopilot pin as it seemed to be in a reasonable location, but it may not be after all...
Will report back next week (assuming the weather plays ball at the weekend) and possibly add photos if I can.
Chris

 

[Pye_End]

One other thing - I had to get mine serviced as too much play developed in the mechanism - you could move the vane too much before the leg moved. It didn't give 30 degree swing, but did stop an optimal beating angle. Thinking about the stiffness, it would have to be pretty stiff to give poor performance in a decent wind - there is so much power available to it when the wind is blowing.
Seafeather I am sure would email you with their instructions. Otherwise if it is the same model as mine I could email them to you. If you pm me with your email address I can send you a photo of mine and you can see if it is the same model.

 

[ibbo]

What direction in relation to the wind are you heading, and what wind speed?
The water vane needs to be set straight ahead when the wind vane is in neutral.
Everything needs to be free.
Chains tight on the tiller.

Mike

 

[Slowboat35]

If its anything like my Sailomat there can be a bit of tuning required to get it to work properly.
Getting the vane perfectly balanced is one (and it isn't a neutral balance on mine) that might cause what you describe.
It sounds as if it may be severly over-damped, meaning it isn't responding fast enough to a course change.

If it is responding quickly then is it taking so much time to correct the swing it gets to 30' before reversing, in which case it might be lack of rudder authority (ie gearing).

Best bet is as others have said, contact the manufacturer for setup and operating instructions and follow then carefully.

 

[Driftingby]

thanks ibbo and Slowboat35 for your responses.
It was a beam reach in 15kts of wind and a reef in both sails to ensure she wasn't overpowered, doing about 5 knots - certainly hand steering was negligible effort or correction needed.
I'll double check the water vane is dead ahead with the wind vane in neutral and also that the wind vane is balanced next time I go out. I also plan to (temporarily) move the rudder connection point to see if that has any effect.
Failing that it will be a call to Sea Feather next week......

 

[Slowboat35]

Note my remark about the balance of the vane. "Balance" does not imply it is neutrally balanced. The Sailomat requires you to find the absolute neutral balance point in still air (preferably indoors) and then offset the balance weight by a significant given amount. Yours may be different, but if you don't know what offset (if any) to give your search for a well tuned vane may be a long one.

A point of sail with absolutely neutral helm is indeed theright place to start.

Friction.
You can tell perfectly well by moving the vane if the paddle moves freely, and equally by swinging the unit if it moves freely on it's fulcrum and whether the control lines are binding. Everything should be almost friction free and any binding or stiffness ought to be quite apparent. I'd be surprised if that was the problem. Equally any slack in the response between vane, paddle and actuating arm will be quite evident and easy to trace.
Do the control lines maintain their tension on both sides throughout the range of travel of the oar actuating the arm? (They should do more or less but certainly with no significant slack in the lines) Poor line geometry could easily cause significant slack and sagging on the non-pulling side that could result in overruns until the unit caught up and pulled the slack out from the other direction. Rigging for correct line tension will probably be important.

Talk to the manufacturer and get their setup insstructions - the dynamics of these things are not always intuitive and without their insight I feel you are likely to have problems figuring it out yourself. With instructions they should suddenly become quite amenable!

Below I've posted Sailomat's rigging instructions as an illustration of what may be important. I hope the system will tolerate such a large post and I don't pretend this is all entirely relevant to a Sea Feather.
What I do suggest is that it might give you a feel for what are the important aspects of rigging such a unit and the bits that are critical - correct positioning in the vertical plane for instance, line routings and tensioning, line geometry, balance etc.

It's not hard, just takes a bit of time and effort but the results will be well worthwhile.

 

[Slowboat35]

 

[SteveAus]

If the vane is pointing at 180 degrees to where it should be pointing, it will cause the symptoms you describe. The counterweight should be to windward of the vane support post.
Regarding balancing the vane, I find it best on my windvane (not a Sea Feather) to have the vane perfectly balanced. As well as the main counterweight, there may be a second counterweight to balance the weight of the rod which connects the vane axis to the gear axis, but I am not familiar with the Sea Feather so the second counterweight may not be adjustable.

 

[half tonner]

Some vane users attach an 800 mm long piece of spinnaker tape to the top trailing edge of the vane. I believe this helps it pull the vane over quicker to make it respond better and help it keep a better track. The OP is suffering because the vane is not responding quickly enough.
That suggests bearings, friction, vane balance, incorrect line setup, or too small vane. All need investigation, but well worth the effort because when it works one would never go back

 

[Driftingby]

Slowboat 35, AteveAus and half tonner, thanks all for your comments. Plenty for me to investigate and try at the weekend.

One question - to remove the issue of sail trim for the time being is there any reason the wind vane wouldn't work when under engine power??

 

[half tonner]

The cavitation from the prop may cause imbalance

 

[Iliade]

After first checking that there is no mechanical fault you may need to look into PID control theory.

Oscillation is typically caused by an over large proportional response to the error, so you could try something to reduce that. Maybe a smaller vane?

 

[Daydream believer]

An easy way to check that is to put a light shock cord from the weight to the main body to restrict movement a bit

 

[Pye_End]

Slowboat 35, AteveAus and half tonner, thanks all for your comments. Plenty for me to investigate and try at the weekend.

One question - to remove the issue of sail trim for the time being is there any reason the wind vane wouldn't work when under engine power??

Sea Feather recommend not having the leg down when under power. Not sure why - perhaps risks when in reverse?

 

[Petronella]

Assuming there is no significant friction anywhere I would check that:

1. The wind vane is not pointing 180° to the direction it should point.

2. That there is sufficient weight to bring the wind vane back to vertical.

 

[Slowboat35]

No use under power is usually cited as the turbulence (not cavitation) of the propwash against the oar could lead to damage/premature wear of the unit.

Thinking of this 30-40' swing...something is fundamentally wrong in the setup here, I doubt this is a mere rigging tweak.
Petronella's (and SteveAus') replies are sensible ones, I doubt the vane wants to be neutrally balanced, it seems to me more likely to respond with a significant righting effort from the counterweight (Sailomat's kilo or so of weight is dropped an inch or so below the neutral balance position) to aid the righting moment.
The point about it being 180 out of true is well worth checking.

Tiller attachment. Most installations I have seen use a point about where a pushme-pullu autopilot attaches, indeed the same pin is often used ie about 12-18in from the rudder post should work. (6 inches or 30 inches probably wouldn't.) I doubt the exact position is critical within that sort of range.

Checking the vane action at the dock...with as 'clean' a wind as you can get;

With the vane removed and tiller line disconnected rock it's mounting from side to side. It should move full deflection without binding and the oar should rotate in sympathy. Stiffness, binding or lack of full and free travel stop to stop needs to be examined and rectified. That should prove the mechanical vane to oar linkage.

Replace vane and using the course selector point the vane to align directly with the wind. It should stand up vertically. Even a slight change in the course selector (or wind direction) should cause the vane to lean over. Returning to the original course setting should see it spring right up vertical again. Straight away. Indeed you may even be able to vary or 'play' the angle of the vane with subtle changes of course selector. If the vane lies over and won't come back up without greatly 'overshooting' the original course setting something's amiss with the vane's setup. This test will tell you if the fault is with the vane part of the system.

Then look at the setup of the oar linkage. Refit tiller lines. Ensure they run freely. Grasp the oar and move it side to side. It should not only move freely without noticeable binding but also move the tiller quite significantly - within the range you'd expect to use to make moment to moment course corrections in a seaway. Does it? Do the tiller lines on both sides retain (most of) their tension all the time. Much slack on the non-pulling side with the tiller over will cause all sorts of errant behaviour, and this is down to poor geometry of the lines' setup)

Look at windvane videos on youtube to get an idea of how a vane behaves. Does yours look like that or is it behaving significantly differently (eg lying hard over for long periods?)

If it passes these tests and still doesn't work I'll admit defeat!

 

[Driftingby]

Thanks all for the comments about use under power - glad I asked first.