reefing a rigid wing sail

Discussion in 'Boat Design' started by endeavor, Dec 18, 2013.

  1. endeavor
    Joined: Dec 2013
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    endeavor Junior Member

    Hey everybody! I'm new here, and this is the very first time I've started a thread, so please don't tear me apart right away.
    I have always been a big fan of wing sails, and think that it would be fantastic if they were used on more boats other than just C class catamarans, and buku bucks America's cup catamarans (and a $10 million trimaran in 2010). Currently I am thinking small boats specifically, but if it would be possible on bigger boats, then even better (i know i was very general - small boat = <30 ft. and bigger boats = >30 ft.) I mean, just imagine the flying phantom project with a wing sail...
    But there are the issues that would prevent something like this from going into production:
    1) Expensive
    2) Not practical to put away sails, or even store them for the winter

    1. the price would drop as soon as it goes into production and people start buying it (most likely).
    2. as far as putting the sail away, the sail must have similar properties to a soft sail (be able to roll/fold it)
    There are soft wing sails such as http://www.omerwingsail.com/ but that already exists, and has not take off. However, one idea they implemented that I liked was the many horizontal components that can be tied down to reef it.

    What if there were similar components in a rigid wing sail, but instead of being covered with just cloth, have the same frames as used in current wing sails, covered with the plastic, but have them hinged between the horizontal components. just as the cloth folds up at the bottom when reefed/lowered in the Omer wing sail, the outer material between the horizontal components would simply fold at the hinge which would be half way between the horizontal frames, and fold outwards. I will post a sketch .

    I also had another idea: if the front (first) element of the wing sail was solid, and the second element was soft. The first element would be similar to the large wing mast on Jet services, or any of the boats similar to that. The second element would have to be fully battened (or even a design similar to the Omer wing sails), and it would allow the very specific shapes of the wing sails. By lowering the rear component, the wing sail reduces its SA to about half, and there are many boats with freely swinging (large) wing masts, and they simply point into the wind without a problem. I will post a sketch for this one also.

    I was wondering if anyone has done something like this before, or if anyone had any other ideas for reefing a rigid wing sail. Also, if anyone has any suggestions/ideas to implement, I would love to hear from you. Just please only constructive criticism - I don't need you to pointlessly tear me apart - I have my school colleagues to do that for me.

    Thanks, Rocky
     
  2. endeavor
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    endeavor Junior Member

    Here are the promised sketches of the two ideas I had.
    Sorry about the crumby quality. It is just a rough sketch. The pics should get better as I develop the idea, and figure out all the little details of how it will work.
    Please let me know if you see any flaws, or anything that would help improve the design.
    --
    Rocky
     

    Attached Files:

  3. messabout
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    messabout Senior Member

    Wing sails are powerful when trimmed precisely right. Therein lies the problem. Wing sails are not an every man practicality. The AC70s have a zillion dollars worth of telemetry/feedback gizmos that inform the helmsman and tacician of correct trim and course. That is not in the financial realm of the weekend sailor or even the serious club racer.

    Another drawback is the wing itself and the aloft weight that it brings. The wing must be built of the most exotic materials to keep the aloft weight under some semblence of control. Exotic matererials equal exotic cost.

    Maybe sometime in the future we will be able to take care of the various drawbacks with advances in technologies and.......... prices.

    What does one do with a moored boat? The wing is standing there ready to exert its influence in accordance with the vagaries of the wind. Not a fun night aboard while on the hook.

    There are too many problems, at this time, to be resolved for the wing sail such that it might become common.

    All that said: I am also fascinated by the concept. I even built a small wing with a soft aft section one time. It was a lot more fun building it than it was to try to figure a way to utilize its probable potential. Building a wing on a backyard basis is no more complicated than building a model airplane wing. Making it work well is a whole other ball game.
     
  4. endeavor
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    endeavor Junior Member

    Dear messabout,
    Thank you for your reply.
    I guess you are right about the wing sails, and that it will still be a long time until they are put into production for the everyday sailor. I know that this has the same drawbacks as putting the folding wing sails into production, but the other practical solution that I saw with the folding rigid sail was that it could be used for ocean racing/sailing other than just on the course, because it could be reefed. Granted, this opens up a whole other slew of problems regarding extreme stability and strength to withstand storms, but it opens up many new doors.
    enough dreaming.

    Realizing all this, I guess I should change my question a bit: How would a soft 2nd element compare to a rigid 2nd element (on an RC model, or a Hobie 16)? Would the performance be even somewhat comparable?
     
  5. frank smith
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    frank smith Senior Member

    I thinking a 3d printed version with the telemetry feed back and surface modulation built in as part of the printing process, but thats a few years away.
    how about a segmented sail, in which the segments slide in side one another.
     
  6. endeavor
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    endeavor Junior Member

    Dear Frank Smith,
    I was thinking about that idea for a while, but 3 things:
    1. the sail tapers as you go up - maybe that's not a bad thing, but it reduces the amount of possible surface area.
    2. If I understand you correctly, it will be similar to a telescope/antenna?
    It would be possible, but difficult to do without a track system (and the track would be sticking out (creating drag) from the segment.
    3. It would be difficult to make it structurally sound without any interior supports (and for now that is my biggest issue)

    I don't mean to shoot down your idea - I really appreciate your input, and will think more about it to see if I can come up with a practical mechanical solution to make it work in reality.

    As far as full sized boats go, I think that this would actually be the best solution, because when the "sail" is down, it is merely a small foil section on deck at the base of the mast. it will be very contained.

    Oh, another thing that just occurred to me: There has to be a way to mount the second element of the wing. This will be a whole other issue for any collapsible 1st element wing. As far as I can tell, on the Hydros team for the C class catamaran, and the AC 45's the 2nd element was mounted on to the horizontal struts from the 1st element on hinges. If the 1st element collapses (folds/changes shape or size), then the 2nd element could be on it's own little mast... or is there another way to have the 2nd element stand on its own?
    it's a work in progress :D
     
  7. Petros
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    Petros Senior Member

    you have several other factors working against you as well besides the ablity to reef and the more costly structure.

    there will be a lot more maintenance on the parts, they would have to be strong enough for cruising long distances in heavy weather making it heavier and with more things to malfunction.

    Most yacht rules specify sail size/type etc. along traditional designs, so an owner of such a sail would be shut out of any club racing since there is no category for it.

    but mostly I think it is market acceptance; most people who buy a pleasure boat want it to look traditional, not like part aircraft and part boat. It is unattractive to potential customers who want their boat to look like all of the others, or like the way sail boats always used to look like.

    This last item I suspect is the single largest market limitation to significant improvement in sail design among recreational sailors. You do not see people clamoring for innovative sail designs on the pleasure cruisers. Only among a tiny few who are serious about performance and are willing to experiment with new designs.

    I think if wing sails were ever to become popular among cruisers you would first have to develop an advanced design sailing rig that appears to have traditional form, so to the average observer the rig looks a lot like all of the the other sailboats, but has a lot of the advanced design features built into it so it performs much better. Once that has occurred, than moving on to a more advanced unconventional rig might be more acceptable to the typical recreational cruiser.
     
  8. PAR
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    PAR Yacht Designer/Builder

    A point not mentioned yet and probably a huge mitigating factor is "what are you getting from this contrivance". You have to justify this type of innovation in a quantifiable manner. If you pull the soft main off a Swan 53-2 or Hyalas 56 and install a rigid, what will the marketable improvement be? Simply put, if you can't sell it . . .
     
  9. endeavor
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    endeavor Junior Member

    Those are very good points. I think we can agree that wing sails will not be found on any cruising boats in the near future, however what about the Moth sailboat. As much as I love the boat, it has got to be one of the most unappealing designs (to the eye) I have ever seen. How did they market that design? Was it because of the drive to beat any other boat in the relatively open class at all costs? What about kiteboarding?
    The moth and kiteboarding do have something in common: A developmental class with the consumer target being the younger generation.
    Granted, all this is just dreaming, but if a developmental class were to take off, it would publicize wing sails. People buy what is proven and what is around. They buy what others have. I asked around, and all my colleagues agreed that they would spend the extra money on a wing sail if there were more around, and they were proven. Just throwing it out there.
    How long will it be until the wingsail becomes a common thing among people? Probably not in my lifetime, but we can at least help with the design process for the day that it does take off. Just dreamin a bit here.
     
  10. lohring
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    lohring Junior Member

    Wings pointed into the wind have lower drag than conventional masts and rigging. C class catamarans can be moored with the wings up, but shifts and puffs require very quick response to avoid capsize since the wing develops lift quickly. However two different autonomous sailboats, sail drone and harbor wing, use non reefing wings successfully. The record land yacht, Greenbird, also uses a fixed, non reefing wing. Their wing control system helps automatically hold a fixed angle of attack. No one would permanently moor a boat with the wing up, but while actually sailing, reefing a wing with a good control system may not be needed, especially on a lower performance boat like the two drones.

    Lohring Miller
     
  11. PAR
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    PAR Yacht Designer/Builder

    I think a better solution is a semi rigid, reefable sail. I've been playing with this concept with mixed results over the last few years. You get the shape, efficiency and control of a rigid wing, yet it can be reefed and doused for an appropriately pragmatic rig.
     
  12. endeavor
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    endeavor Junior Member

    That is true that they do not need to be reefed (but they are also lower performance: average=3-5 knots...), and my goal was to create a high performance wing sail. That being said, is there any way to use the concept of the trailing wing on a 2 element wing sail, or does it need to be one element for it to work? Is it possible to trim the large 2 element wings in a similar fashion to the sails on the drones to dramatically reduce power without having to reef? I'm not familiar with how the 1 piece, self sailing wings work. I have seen them, but not paid much attention to them.
     
  13. endeavor
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    endeavor Junior Member

    What exactly do you mean by semi rigid? Do you have any sketches or pictures of what you have in mind? The soft wingsails look good, but those also seem nearly impossible to reef. I can't seem to picture what you have in mind, but I would love to know.
     
  14. Baltic Bandit

    Baltic Bandit Previous Member

    if you can build an unstayed wing mast, you don't have to reef it at mooring either - let it feather in any direction.

    But the real issue with wings is that at the low speeds most sailboats operate, you really need a 2-3 element wing and trimming it is non-trivial.
     

  15. PAR
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    PAR Yacht Designer/Builder

    Much experience with feathered wing sails have you? Good luck with that tactic . . .
     
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