Wing Sails on Proas!
This is another story for jibes. As it can be seen on the videos from Peter Worsley, in that case there is the tail caught backward, until the wind angle is such that every thing flips around, like a normal jibe….
Not quite. Please see this vid: http://player.vimeo.com/video/77253491?portrait=0 from about 2:20 onwards, the boat is sailing downwind. Look at the wing; the “tail” is out over the bow and the counterweight is trailing. The wing is at between about 100 degrees and 170 degrees to the hull, but the rig is in fact maintaining the same angle to the apparent wind throughout, upwind or down.
When the boat jibes (not shown in the vid), the tailplane goes past the wind, tail downwind, identical to when the boat tacks. There is no banging over as the sail reverses, no drama at all. The hull can sail on any course where the wing’s net thrust is in a forward direction. The rig maintains the same angle relative to the wind at all times (unless and until the rig control, the “throttle,” is altered. Note that this can be never, and the boat still sails happily whatever course is set by the rudder.) Simple. Sublime?
Dave Culp
If the circular cam actuates the follower by sliding “sternward” the distance from the follower pivot to the tangent point on the cam is much shorter so you have more angular movement of the follower when the cam actuates by moving closer to the follower pivot.
Thanks for that explanation Skip. While I can see that the benefits of the cam being usually closer to the pivot are as you describe for a regular sailboat does it apply to a proa which goes backwards as much as it goes forward ?
Peter H
If the circular cam actuates the follower by sliding “sternward” the distance from the follower pivot to the tangent point on the cam is much shorter so you have more angular movement of the follower when the cam actuates by moving closer to the follower pivot.
Thanks for that explanation Skip. While I can see that the benefits of the cam being usually closer to the pivot are as you describe for a regular sailboat does it apply to a proa which goes backwards as much as it goes forward ?
Peter H
I think so since as I understand it, the process of shunting would involve moving the cam from one direction to the other. For something that is so brilliantly simple, Worsley’s circular cam has been hard for me to completely digest mentally. Having three or more independent but inter related axis (heading, apparent wind, angle of w-sail to boat, incidence of tail and flap….) whizzing around concurrently is hard for this old mind to grasp.
Looking back at videos of Worsley’s earlier iterations of the wingsail it looks like he arrived at the current state of development the old fashioned way, he worked for it.
Cheers,
Skip
This is another story for jibes. As it can be seen on the videos from Peter Worsley, in that case there is the tail caught backward, until the wind angle is such that every thing flips around, like a normal jibe….
Not quite. Please see this vid: http://player.vimeo.com/video/77253491?portrait=0 from about 2:20 onwards, the boat is sailing downwind. Look at the wing; the “tail” is out over the bow and the counterweight is trailing. The wing is at between about 100 degrees and 170 degrees to the hull, but the rig is in fact maintaining the same angle to the apparent wind throughout, upwind or down.
When the boat jibes (not shown in the vid), the tailplane goes past the wind, tail downwind, identical to when the boat tacks. There is no banging over as the sail reverses, no drama at all. The hull can sail on any course where the wing’s net thrust is in a forward direction. The rig maintains the same angle relative to the wind at all times (unless and until the rig control, the “throttle,” is altered. Note that this can be never, and the boat still sails happily whatever course is set by the rudder.) Simple. Sublime?
Dave Culp
Dave,
I was referring specifically to the mechanical system devised by Peter Worsley (we need to get this guy on this forum!!!).
If you look at one of his earlier videos here:
http://www.youtube.com/watch?v=HhUllUd-QUA
At 45 seconds, you see clearly a “conventional” jibe.
On the other video from Peter Worsley, that we all have been referencing, you will notice that you do not see a single jibe or tack… It is all a beam reach on one tack and another beam reach on the other tack, with the operator (Peter Worsley himself?...) walking along… Why no change of tack on the video?
You are most likely correct that it is not the case for saildrone; but saildrone is using electronics and actuators. On controls philosophy, I consider it a completely different beast. They do not clearly state if the actuators are only for the rudder or also for the wing. On their videos, it is clear that the wing is a single element wing, with a tail to put the wing into the wind with a given angle of attack to generate lift. It is also clear that the tail has a flap (rather than on the main wing to generate camber like we have talked about earlier for Peter Worsley set up). I suspect (but I do not have proof…) that an actuator, controlled by the “electronic brain” of the vessel plays the angle of the flap on the tail, which generate lift on the flap in one direction and therefore turn the main wing in the opposite direction. You can see the flap in action in the following video at 20 seconds. The broken line for the trailing edge of the flap is the telltale… if I may say…
http://vimeo.com/77253491
From the pictures on the front page of saildrone.com, I believe that the only moving part on the wing assembly (other than the whole rig turning around above the boat) is that flap on the tail. It seems that the tail is solidly attached to the pole going through the wing and extending forward to the counterweight. There is apparently no articulation anywhere but at the flap. A super simple design with impressive reliability, at the expense of some performance, of course.
To sum it up, I think we agree that once you have an unstayed rig with no control lines going back to deck that could get tangled up if your rig is doing a 360, there is no reason NOT to do the 360 when necessary!
Saildrone can do that, at the expense of electronics, software, solar panels, etc.
Peter Worsley purely mechanical design of “set it and forget it” simplicity cannot; unless you accept that you fiddle with the cam position during jibes…
Cheers,
Laurent
Thanks for that explanation Skip. While I can see that the benefits of the cam being usually closer to the pivot are as you describe for a regular sailboat does it apply to a proa which goes backwards as much as it goes forward ?
Peter H
I think so since as I understand it, the process of shunting would involve moving the cam from one direction to the other.
Hi Skip,
Thanks again - I think I get it. Irrespective of which direction the boat is heading (i.e. no matter if the control lever is set ‘forward’ or ‘reverse’) with the wing anywhere from broad reach to close-hauled the cam is closer to the pivot than the mast is. So the cam has a greater effect on the angle of the tail.
Peter H
Hi Dave!
Some notes on the (im)Practicality of wing sails:
Others have related most of the old saws about capsize danger, raising/lowering, reefing, storage/transport, cost and weight issues (did I miss any?) I’ll touch each if I may. You’ll note a recurring theme; let’s look at comparable challenges between wings and masted sails, not absolutes, and let’s look at an evolutionary route, not a fully-formed pandemic solution to every potential problem.
I guess I’m one of the people you’ve classified as an old sawyer. Culpable you might say.
Part of the benefit of public fora is that different viewpoints can be posted - although some people would prefer the controlled messaging of corporate brochures and websites - places like Proafile are dangerously democratic.
I’m very interested in wing sail developments - I’ve sailed with folks from the Toronto-based C-Class contingent as well as Steve Clark and the folks from his Lab of Luxury in Rhode Island. I’ve been developing and delivering products for many years, and I’ve found objectivity and balance to be a high valued asset. I’ve learned the hard way to pay more attention to critics than supportive folks.
Capsize danger. Yup, it’s there. Same as in your garden variety multihull. Jam a winch and you can’t release the sheet and over you go. Let the main all the way out to the stays on a run and you can’t get the sail down—and over you go. Sail into the “broad reach multihull trap”, where you’re over-canvassed but holding your own by bearing further and further away—until you realize there’s no more to give ‘cause you’re on the edge of pitchpole—and you also cannot come up or the fast-shifting apparent wind will capsize you—and over you go. So sure, a jammed wingmast could spell catastrophe at sea. Be a good idea to keep those bearings in good repair, wouldn’t it? $10 million AC boats with 13-story wings might want to leave someone aboard on watch, but I don’t think a 16’ proa will have the same issue. It is quite common for the AC45 fleets to leave their boats on moorings—interestingly they use large bags of fresh water as mooring buoys-these are hard to drag around, but *can* be, so make good shock absorbers to keep the boat from “hunting” around its mooring (fresh water floats on salt)
RCYC in Toronto is a hub of development and training for the C-Class. They’ve built, tested, damaged and resuscitated more wings in the past ten years than any other C program. Thankfully they’ve got deep pockets and deeper knowledge and experience so the process has continued unabated. Dropping a wingsail into the drink will never be as affordable as replacing a conventional spar. Generally a wing sail capsize is ugly - flooding the wing, damaging skins, panels, frames and often core spars. The same guys who sail the C-Class boats form the local I-14 fleet - and they capsize the I-14s without incurring any cost but a swim and debate on refreshment purchaser liability. A C wing sail going down is a very expensive event even if things go as well as possible. Ask Steve Clark about his testing and capsize of Aethon prior to the 2010 Newport C-Class Championship.
Capsize on a wing sail boat is not the same as a garden variety multi-hull.
Gary Baigent in New Zealand has built and owns multiple wing sailed foilers - another performance cruise boat is on the design board right now. He’s now conceded he needs to drop his wings when moored - the risk and damage done leaving a wing up unattended is too high. He’s already accumulated more real experience “living” with wing sails than most of us ever will.
Storage/transport. It’s a good idea to split the wing into 2, even 4 major pieces, especially if it’s of any size. Richard’s is a good approach for a single element wing—you could almost as easily cut the wing horizontally into 3 as into 2 and have even more “reefing” choices. Second, it’s a good, practical idea to split the wing into 2 elements. The resultant pieces are much smaller, thinner and lighter than the single element. The connectives aren’t tricky or fragile; the C class cat guys have had it all figured out for many years and have fully published it for free—including a remarkably simple and precise twist control system, if that interests you (it doesn’t me—if a wing gives me 20% more power and speed, I believe I can forgo the additional 2-3% I’d get by precisely controlling twist. Plus the C-cat guys offer even simpler twist systems which aren’t adjustable. YMMV)
The RCYC team built four trailers/containers for transporting their C-Class defender to England for the last Little America’s Cup - multiple wings, boats and a portable composites shop, parts inventory & engineering team capable of on-site repairs and rebuilds. Following C-Class traditions, they shared everything and the composites experts were working almost 24/7 to keep competitors on the water.
Weight and cost. Again, yup, they’re issues. Design ‘em light and strong, then re-design them light, strong and of cheap materials. I’m working on it…
Great. Because the ante has got to come down a lot for more people to be able to sit at the table. Pre-preg and autoclaves aren’t in my garage-build future. I just can’t see enough volume potential to make low-cost production economically viable. The problem isn’t interest, it is affordability.
I’m of the opinion that this is one of those “horses for courses” situations where leading edge technologies may not ever make it back to the more affordable trailing edge most of us live at. I certainly hope innovators like you can do your magic.
—
Bill
I was referring specifically to the mechanical system devised by Peter Worsley (we need to get this guy on this forum!!!).
>
Peter’s email is Peter “at” sailwings “dot” net. Please do invite him, he’d be thrilled.
> If you look at one of his earlier videos here:
> http://www.youtube.com/watch?v=HhUllUd-QUA
>
> At 45 seconds, you see clearly a “conventional” jibe.
The crux of your answer is in your statement, “earlier.” Peter’s been working on this for many years, there are vids of several earlier iterations, which behave in various ways. I learned of the current iteration’s capabilities by… asking him. Sum total, the thing *does* auto-tack and auto-jibe according to Peter, can turn 360 degrees without fouling, and is 100% mechanical. This is what Peter says, and is also what he demonstrates, manually, in the vid (the one of the device on the lawn as he sets, manipulates and partially disassembles the thing). If he has erred, I take no responsibility. 😊 OTOH, there’s his email addy; you may interview the horse’s mouth.
> On the other video from Peter Worsley, that we all have been referencing, you will notice that you do not see a
> single jibe or tack… It is all a beam reach on one tack and another beam reach on the other tack, with the
> operator (Peter Worsley himself?...) walking along… Why no change of tack on the video?
I don’t think he created the videos to “sell” the concept; he doesn’t offer plans ad believes that this vid is self-explanatory—that anyone could build and use the mechanism just by watching the vid.
You are most likely correct that it is not the case for saildrone; but saildrone is using electronics and actuators. On controls philosophy, I consider it a completely different beast. They do not clearly state if the actuators are only for the rudder or also for the wing. On their videos, it is clear that the wing is a single element wing, with a tail to put the wing into the wind with a given angle of attack to generate lift. It is also clear that the tail has a flap (rather than on the main wing to generate camber like we have talked about earlier for Peter Worsley set up). I suspect (but I do not have proof…) that an actuator, controlled by the “electronic brain” of the vessel plays the angle of the flap on the tail, which generate lift on the flap in one direction and therefore turn the main wing in the opposite direction. You can see the flap in action in the following video at 20 seconds. The broken line for the trailing edge of the flap is the telltale… if I may say…
http://vimeo.com/77253491
Good points, all. I believe the thing you identify as a “tail flap” is more of a trim tab, also that the entire tail plane likely does move, just isn’t moving enough to see on this vid—this is exactly the combination Richard used on GreenBird (though he manually actuated the tailplane on that version—the trim tab in this one would reduce the power necessary for course keeping by at least an order of magnitude—I expect that close examination might show that the tailpane is aerodynamically balanced, too. That’s fairly standard for these.
To sum it up, I think we agree that once you have an unstayed rig with no control lines going back to deck that could get tangled up if your rig is doing a 360, there is no reason NOT to do the 360 when necessary!
Saildrone can do that, at the expense of electronics, software, solar panels, etc.
Yep, though there are other ways. Turns out that the “standard” way the R/Cers (and land yacht wingsail guys) do it is with an in-mast push-rod, actuating a control horn at the top of the stub mast. This was pointed out by someone earlier in this thread. Peter’s bottom-of-wing cam and follower are a clear improvement over the pushrod(s), in my opinion
Peter Worsley purely mechanical design of “set it and forget it” simplicity cannot; unless you accept that you fiddle with the cam position during jibes…
No fiddling. Honest.
Dave
> Cheers,
>
> Laurent
I love Saildrone as a piece of design but can’t help wondering whether its apparent success has been achieved because of things you can only do (or would only want to do) in a drone and don’t scale up realistically into manned boats.
I can’t believe that it hasn’t capsized or rolled over in ocean conditions in its many thousands of miles of travels. I would love to know if they have monitored or kept records of this.
What I can believe is that there is enough buoyancy, watertightness and robustness in the entire setup that when combined with the design and disposition of the buoyant elements, that the drone either lays flat in the water until the capsize forces have passed and then rights itself or even if it has rolled, it has enough inertia and instability in the inverted position to roll back up the right way and carry on with its mission.
To get that kind of robustness in the rig obviously is possible (and relatively easy at drone scale) but would mean a lot of weight up top which means good initial capsize resistance but would be accompanied with heavy if not violent pitching and rolling in rough conditions.
Drones don’t get seasick or spill their load all over the place inside when lat flat or rolled and don’t get tired of doing it repeatedly for an entire voyage so it doesn’t matter. They just sort themselves out and press on as programmed.
I also wonder what price has been paid in overall performance to achieve this?
I love Saildrone as a piece of design but can’t help wondering whether its apparent success has been achieved because of things you can only do (or would only want to do) in a drone and don’t scale up realistically into manned boats.
I can’t believe that it hasn’t capsized or rolled over in ocean conditions in its many thousands of miles of travels. I would love to know if they have monitored or kept records of this.
What I can believe is that there is enough buoyancy, watertightness and robustness in the entire setup that when combined with the design and disposition of the buoyant elements, that the drone either lays flat in the water until the capsize forces have passed and then rights itself or even if it has rolled, it has enough inertia and instability in the inverted position to roll back up the right way and carry on with its mission.
To get that kind of robustness in the rig obviously is possible (and relatively easy at drone scale) but would mean a lot of weight up top which means good initial capsize resistance but would be accompanied with heavy if not violent pitching and rolling in rough conditions.
Drones don’t get seasick or spill their load all over the place inside when lat flat or rolled and don’t get tired of doing it repeatedly for an entire voyage so it doesn’t matter. They just sort themselves out and press on as programmed.
I also wonder what price has been paid in overall performance to achieve this?
I assume that the Saildrone has a ballasted keel, and that the amas have only been added to help maintain a smaller heel angle, probably helpful for it’s intended duties. Seems a fairly draggy design, the short amas spend a fair bit of time fully submerged and the akas are immersed as well. The quoted speeds are very modest for a 19 ft vessel. Lots of compromises for sure.
Saildrone specs:
Length: 19ft (for transport in a 20’ container, 6 Saildrones per container)
Width: 7ft
Height: 20ft above water surface
Draft: 6ft below water surface
Average speed: 3-5 knots
Maximum speed 14 knots
In the pic below, the tailplane rudder appears to be fixed with only a small moveable trim-tab. Classic airplane geometry.
In the pic below, the tailplane rudder appears to be fixed with only a small moveable trim-tab. Classic airplane geometry.
I guess that is a fairly robust solution. The moving section is small and well supported. If the flap does fail, the wing will self feather. I assume that fairly large flap deflections are required to rotate the wing.
I was just thinking of the possibilities of a schooner rig with one of these wings on each end of the vaka. Perhaps with two lifting boards for coarse CLR control, all of the steering could be easily done with the sails.
Mal.
I guess that is a fairly robust solution. The moving section is small and well supported. If the flap does fail, the wing will self feather.
Only if the flap fails in its undeflected state ?
I was just thinking of the possibilities of a schooner rig with one of these wings on each end of the vaka. Perhaps with two lifting boards for coarse CLR control, all of the steering could be easily done with the sails.
Two minds - see #33
Two minds - see #33
Oh yes, missed that.
This is getting good.
This is the way I see wingsails on real boats. Unlike the glamour of the AC and Little AC cats, wingsails are NOT for high performance. They are for solid, easy, dependable, predictable thrust, come what may, hurricane or zephyr and anything in between.
Thanks for this, Ed. I completely agree with you, though I believe wings can fulfill both design briefs. Taking nothing away from C’s or AC 45s (There’s a fleet of a dozen housed not 20 miles from where I sit), it was the robustness of the latters’ wings—more than once repairing capsize damage *between* heats, and still making their afternoon starts—that has encouraged me to look into small, tough, cheap wings for, as you say, “solid, easy, dependable, predictable thrust, come what may.”
While I have yet to meet the wing sailor who says, “Hey this thing is boring,” I can certainly imagine some sailors will keep their strings, booms and canvas, and more power to them. I have nothing to sell and don’t seek to bash anyone; it’s a big pond with room for everyone to play. I contend that there’s a continuum of complexity, skill and cost available for wingsail design and construction. We so often hear about the “Maserati” end of this (C-Cats, AC45’s, AC72’s) that we rarely even consider that the Ford Pickup end exists (SailDrone, foam & fir, heat-shrink plastic).
They are perfect for a wind powered drone which has limited ability to make mechanical changes to the rig “on the fly”. This sounds good in theory, but if you are the “drone” sailing across an ocean, you are far more capable than a few servos and a few strings of programming to make changes that benefit the ship. Adjust sail area, tweak the rig, fine tune. What the hell else are you going to do out there? And if it gains an extra knot of or two of traversing the leagues over the sea, then why not?
However, there are plenty of uses for relatively “mindless” wind power. Shipping being the big one. A short handed, limited skill crew could sail a wingsailed vessel from here to there pretty easily and safely, at least a lot easier than a clipper ship.
Combine the wing with an efficient platform (proa), and you have a going shipping concern. Solid, dependable, predictable.
And again, you can make it as simple or as complex as you like. I’m shooting for 2-element low-tech foamies with 100% mechanical control, on boats up to to maybe half a ton and 20-25’ OA, but anybody is welcome to meet the challenge at any technical level they’re comfortable with.
It just disheartens me when I see a design solution encompassing hundreds or thousands of parts, strings and diodes, doing a job better than—but not very much better than—some simpler, more elegant solution anybody could build in their garage. After 40 years of boat design, sailing and building, I’m finding this an enjoyable challenge; it’s not what I can add, but what I can take away—and not miss!
Dave
It just disheartens me when I see a design solution encompassing hundreds or thousands of parts, strings and diodes, doing a job better than—but not very much better than—some simpler, more elegant solution anybody could build in their garage. After 40 years of boat design, sailing and building, I’m finding this an enjoyable challenge; it’s not what I can add, but what I can take away—and not miss!
Yep, though rather than disheartening I usually just mentally dismiss the ornate and complex often overblown solutions out of hand. There is a little danger in that attitude. I had stepped away from model building, robotics and electronic diddling over 30 years ago. Recently got reintroduced to the robotic end of things via helping mentor one of my granddaughters. Things have changed. I just made the guts for a little “arc reactor” 10 leds, an arduino nano microprocessor and a few misc bits. A couple of evenings and the dang thing works like a charm, no hassles other than operator error, no smoke and the potential for a zillion different patterns/ effects. That’s simplicity overlaying some wildly complex stuff. Still digesting what it all means (other than we live in interesting times).
Back to boats, proas specifically. I think there are two elements to this simplification process. First is overall design (my favorite) proas do well here, one hull, one float, wind from one side, some even lean towards no rudders, though I’m leery of the last. A lot of noodling to get the parts just so; that there’s nothing extra and stresses kept to a minimum. Second is the actual building of the beast. While waiting for my shoulder to catch up with the rest of me, I’ve thought quite a bit (more) about building Nomad. Even though there’s been a steady evolution of the concept, seems like there is always room for improvement. My current canoe, EasyB, is the end result of about six very good similar designs plus a multitude of other paddle craft and the very first that I thought “there’s nothing that I want to change”.
Skip