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windvanes

I haven't used this but have read that a small electric tiller pilot can be adapted to a wind vane servopendulum self steering system (like the Monitor or ...) to steer to a compass bearing and is touted to be an inexpensive and reliable method for downwind steering.

See, for example: http://www.selfsteer.com/products/monitor/autoPilot.php

This idea uses the tiller pilot to replace the wind vane and requires very little force or power from the tiller pilot.

I would be interested to hear people's experience with this.
 
good explanation of a servo-pendulum gear by the general. he certainly has sailed enough miles to get a good grasp of how they work!

the gerneral is right jackie, there is no reason at all to strengthen your transom to add a Navik. my 2-27 yachted it's way from CA to new zealand and it's transom is stock.

smokester, SHTP vet brian boschma has been messing with and pioneering systems like you speak of, for years. figure out a way to get in touch with him and he can likely help steer you in the right direction, lame pun fully intended.

cheers.
 
ronnie simpson said:
...smokester, SHTP vet brian boschma has been messing with and pioneering systems like you speak of, for years. figure out a way to get in touch with him and he can likely help steer you in the right direction, lame pun fully intended.

cheers.
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hodgmo said:
Some of Brian's ideas and products are described at

http://validator.stacieboschma.com/products/

One of the videos shows a small actuator motor linked to the Atoms wind vane on Frolic (Islander 36). It worked really well - used it when we motored during the trip back to CA last summer.
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Thank you for steering me in the right direction.
 
Not that this will help all that much, but i have been using the same Hasler SP vane for over 35 years on three different boats. It is a horizontal pivot, so it is not quite a efficient as a vertical, but it is only about 20 lbs, works delightfully, and has proved to be very durable. I replaced the Micarta with Delrin parts for the Transpac, and I have hooked it to a small traveler that is in turn attached to a ST2000 for light air and down wind work. Wear and tear on the ST2000 is near nil as it only has to change the servo blade angle, the blade provides the power to tiller.
 

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[email protected] said:
Not that this will help all that much, but i have been using the same Hasler SP vane for over 35 years on three different boats. It is a horizontal pivot, so it is not quite a efficient as a vertical, but it is only about 20 lbs, works delightfully, and has proved to be very durable. I replaced the Micarta with Delrin parts for the Transpac, and I have hooked it to a small traveler that is in turn attached to a ST2000 for light air and down wind work. Wear and tear on the ST2000 is near nil as it only has to change the servo blade angle, the blade provides the power to tiller.
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That should be a museum piece when the boat is retired.
 
To take advantage of the vast experience here, I am wondering if there is a VMG penalty using a windvane. What little data I have seen--albeit somewhat dated--indicates that they average slightly better than an autopilot except on a beam reach where the data show they are roughly equal.

I have heard anecdotally that the drag and responsiveness of a windvane can produce significant performance penalties for racing. It surely must make a difference as to the type of windvane and boat, sail plan and point-of-sail. My boat is a Pacific Seacraft 37 which is fairly heavy and has a modified fin keel and skeg-hung rudder. Watching the windvane at work never ceases to mesmerize me so I would hate to think I would need to ditch it in favor of an autopilot.

But autopilots have become very sophisticated, sailing to the apparent or true wind, and using motion sensors and adaptive learning to account for boat motion. There is also the hybrid brian boschma.com approach mention below which greatly reduces the power consumption and noise of electrically-powered rudder control.

Most modern sss folk seem to be racing with autopilots...Why is that?
 
Smokester
Take a look at my previous post on this subject (#20). The singlehanded transpac is pretty much a downwind race after you get into the NE trades (400 or so miles out of the gate. That's when the chutes go up to take advantage of winds over your shoulder from behind. Withe chute up, my fin-keel, spade rudder boat will often surf up to 10 or 12 knots from a steady state speed of 6 kts. That's when the apparent wind shifts forward and the vane, which only sees apparent wind, thinks the boat has gone off course. It tries to correct the heading, but that's not what we want at that stage. So the vane users usually end up with a course of "S" turns, travelling farther that if they were to maintain their selected heading. My auto pilot can operate using the masthead wind sensor, but there is a delay in the system which defeats the forward movement of the apparent wind...usually. Or it can operate on a compass course just as easily, but that requires me to be watchful of wind shifts requiring sail trimming.
 
smokester, Harrier is exactly right, couldn't have described the differences better myself. Another thing to think about is the drag in the water of the wind vane rudder/ paddle. On a PSC 37 this may be pretty minimal, but even .1 knots of boat speed adds up to about 40 miles over the course of 16-18 days or so, which is your likely pace. at 6 knots VMG, you're looking at 7 hours, just assuming .1 knot difference which is conservative. when i sailed the race in 2012, the top 5 boats in my division corrected out within 12 hours... 7 hours would have dropped me from first to fourth in class. something to think about if placing well in the race is a priority for you.

wind vanes are absolutely phenomenal from a power conservation/ reliability standpoint and on my recent cruise to New Zealand, the wind vane was the single biggest 'enabler' in allowing me to complete long solo journeys... from a racing/ performance stand point however, a good modern electric AP will reign superior. assuming you have the $$$ to purchase and power budget to run the AP, but that's two entirely different conversations. in a perfect world, a boat like yours would likely have a solid AP and a wind vane for back up/ cruising/ delivery home. sort of like sat phone vs ssb. in the sense of an SHTP, it's often best to have both if resources allow.

ps - sailing downwind in light air with a wind vane blows, and youre likely to see those conditions on a transpac...

good luck mate
 
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Respectfully, I would like to disagree a bit with Mr. Simpson above. Pretty much like everyone else who uses self-steering of a sort, I have wondered about the effects of the drag of a servo blade. I am using an older Hasler SP unit (one of the very first servo-blade units made) so it is a relevant issue to me. So, to sort it out I ran the numbers of my boat and blade through the drag equation (F = 0.5 C ρ A V2) . My blade extends about 2 feet under water, has a chord of 6", and is a NACA 0010 section. Plugging in the constants etc. the results indicate that at 4 knots the force needed to propel the blade through the water is .67 lbs., and at 6 knots it rises to 1.48 lbs. Using the SailPowerCalc website I found that the force generated by my rig (main and 120%) at 9 kn of wind (about my 4 kn range) while beating is 240 lbs of forward drive. So the .67 lbs. of drag represents about .3% of the force driving the boat forward. A .3% reduction of speed represents a loss of .012 kn, not .1 kn. Downwind the drive forces will be much larger due to the force vectors for the sails aligning more directly with the boats heading and making the loss of drive and even smaller percentage. At 6 knots (12 knots or so with a 100%) the drive force increases to 426 lbs. and the servo drag remains at about .3% of the drive force. This results in a reduction of .018 kn. These numbers are squishy for certain, but likely they are accurate enough to get a reasonable picture of the magnitude of the forces at play.

Are there compensatory advantages to a vane then that might compensate for the small speed loss when using the servo-blade to move the tiller/wheel? No argument that reaching and downwind/light air work require an electric autopilot for efficiency. My ST2000 drops from a 1.8 amp draw to a .5 amp draw when I change it form direct tiller drive to the servo-blade drive in moderate air. This saves over 24 amps per day and eliminates the need for a 40 watt solar panel, saving about 12 lbs. The weight of the fuel required to charge that 24 amps over the course of a Transpac would be a good deal more. The wear and tear on the autopilot is drastically reduced as it only needs to change the angle of the servo-blade (a finger tip operation), making it unnecessary to carry multiple spares as suggested by so many (one of last years entries went through three coming down from Washington). There is a lower probability of needing to deal with the possible problems associated with a steering failure (broaches, sail damage etc.). Upwind a vane is generally considered more efficient that a compass driven unit as it responds to every wind shift. And there is the safety factor to consider. If all the electronic devices fail, or if there is not enough sun to recharge, the boat will still quite happily sail in any direction you choose, although with a bit less efficiency (as has happened in the Transpac).

I am not arguing that vanes are the best way to go, only that they represent a very real and competitive alternative to using electric autopilots exclusively. When the autopilot can be linked to the servo-blade for course correction in those conditions where a vane is less effective, a very flexible and efficient system is created. Further, the system has the additional advantage of providing a reliable alternative for steering the boat in the event of serious mishap (some designs can act as the emergency rudder as the General has demonstrated).

One final note. My boat is small and lively and I had difficulty getting the vane to steer reasonably, especially on a reach or downwind. The vane would correct, the boat would over-steer, the vane would over correct the over-steer etc. By setting up the tiller lines with the option of 1, 2 or 3 part purchase (very easy to switch from one to the other) I was able to dampen the course correction down, slow the boats response time which allowed the vane to react in time with the boats change in heading. The result was much straighter tracking and far fewer 'S' turns. While not a par with the ST2000, it creates a track that is quite acceptable for coastal cruising and day sailing without any power drain.
 
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Good comments, Mr. Paine
One more minor addition that I might add: The servo pendulum vanes that I have used, seem to work fine with a "normal" distance of 18 inches from tiller post to steering lines attachment point on the tiller. However, I found that there are times when this tiller attachment point could stand a change under certain conditions. If the attachment distance were shortened, the rudder would achieve a greater steering angle as the lines from the pendulum pulled the tiller over. Conversely, if less rudder swing were desired, the tiller attachment point could be moved farther from the rudder post. Might be better in lite air? Anyway, experimentation will possibly improve one's experience with the vane steering. I added a 12" piece of genoa track to my tiller, with the steering lines led to a "car" which could be moved fore and aft on the tiller. Thus, I am able to vary the attachment in an attempt to improve my vane's performance in varying wind and sea conditions. This is sort of "guilding the lily", perhaps, but it's fun to experiment. In another vein, pun intended, I do not feel that servo pendulum vanes and wheel steering are very compatible. The vane might only provide 6 inches of movement P & S at the tiller, which will give the rudder a good swing. Turning the wheel attachment drum 6 inches along its circumference will not swing the rudder nearly as far. It will generally steer fine up wind, but "run out of rudder" when used downwind. This may not be a problem with all boats, but I know it is with many wheel steering installations.
 
good comments sdpaine. and nice math/ equations/ science to flush out the heresay. I still have a hard time believing the vane's drag only slows the boat down .012 knots. after a lot of sailing on small boats with wind vanes and without, i personally believe it's more than that but i don't have the math or science to back that up. we will respectfully disagree. without differing opinions, this thread/ conversation would be boring.

you are absolutely right though about the weight of the panel/ weight of fuel/ electricity budget, etc. it's the million dollar question on small boats and small budgets. in 2012 SHTP, Ruben and I both left on Moore's and only had solar for charging. we had a cloudy year and ended up mostly hand steering to hawaii which was f'ing miserable, and a Navik would have been really sweet to have on the transom!

horses for courses, we all set up our boats how we see fit, but this is a good discussion. thanks for the input.
 
OK. So the drag of whatever a windvane appendage amounts to, it is still more than NO DRAG. You just decide whether putting up with the drag is worth the benefit of less electricity needed to accomplish the mission. I think I stopped using the Atoms vane around my 3rd or 4th SHTP. Simply decided the auto pilot does a better job on that race in my boat. And the vane shades my stern panels more than I'd like. In so doing, I laid myself open to a potential severe problem in the event of limited solar power and engine failure. So I carry a small gasoline powered generator for peace of mind. Have used it, but never really had to. Life involves choices at every level, it seems,
 
Jackie, go bolt that thing to the transom and learn how to use it! If you're going to sail more distance than your battery can run your autopilot, then have spare parts for the Navik.
 
AlanH said:
Jackie, go bolt that thing to the transom and learn how to use it! If you're going to sail more distance than your battery can run your autopilot, then have spare parts for the Navik.
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Come up and help me bolt it on, then we can go out and practice. I want to have it in place for the Half Moon Bay race and certainly for Drakes Bay (cuz it's so far away!).
 
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Dave, thanks for the reminder about Mister Vee. Has anyone heard anything about their "Y&B" windvane? It sounds robust enough for my boat but it's half the weight of the Monitor due to using modern materials. I just can't put 55# on Rags' transom - I'd need a sissy bar - 24# would be okay though.

They also sell a "headless" version to use with a tillerpilot, which would work during surfing sessions.
.
 
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DaveH said:
For what its worth, it actually is fairly easy to find spare Navik parts... these guys are in Holland, but super easy to work with.
they are not OEM parts, but they have replicated them and generally have inventory on all the fiddly little bits. http://windvaneselfsteering.com/content/navik-spare-parts
best,DH
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Actually, my experience with Mr Vee was not so helpful. Someone offered to give me a Navik a couple of years ago, but it was missing a paddle. I contacted Mr Vee and he told me that it was not cost effective for him to make only a small batch of one or two. My understanding is that paddles tend to go missing offshore, and it would definitely be a good idea to have one or even two spares. I'm sure a paddle could be fabricated by people who know how to do that sort of thing (Greg Nelsen, Chris @ Svendsen's) but Mr Vee wasn't interested in selling only one or two. And by the way, if someone needs a wheel adapter for his/her Navik, one came with my Navik when I bought it. It has never been used and is in great shape.
 
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Yes, in fact they do a run of windvane systems just once a year. The farther ahead you order, the larger the discount.

But spare parts like the paddles/blades should be available year-round. It does make me think about putting my eggs in their basket.
 
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