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Thread: Voyages of Arawana

  1. #3676
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    Plastic Fabrications in Hobart could make a pretty neat custom HDPE pram dinghy. I bet the price would be eye watering, but it would be tough as nails. Possibly cheaper to have a custom aluminium dinghy made.

    But for a good combination of lightweight hull and cost effectiveness its very hard to go past S&G plywood dinghies.

  2. #3677
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    Default Re: Voyages of Arawana

    Quote Originally Posted by Snow Pea View Post
    Plastic Fabrications in Hobart could make a pretty neat custom HDPE pram dinghy. I bet the price would be eye watering, but it would be tough as nails. Possibly cheaper to have a custom aluminium dinghy made.

    But for a good combination of lightweight hull and cost effectiveness its very hard to go past S&G plywood dinghies.
    I built a S&G tender for about $200 I think it was.
    The definition of stupid has got to be the belief that more guns will negate the bloodshed done with guns.

  3. #3678
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    Quote Originally Posted by brucemoffatt View Post
    I have to ignore my own judgement, and share my thoughts on how I am intending to proceed with experimenting with a vane-to-tiller system. I need to articulate my thoughts, both to help clarify them in my mind, and to try to get enough interest here to get the great power of the interweb hive-mind applied to the proposal.

    I've decided to try to make a working version of a vane to tiller self-steering system. Belcher has good info. Others have built working examples, see below, yet Belcher states the limitations, as does the maker of the Aristo system, i.e. that it works for small boats with light helms and well balanced sail setup, and not very well in light winds.

    What I haven't seen so far, and I may well have missed, is a well designed vane blade, designed to maximise the available wind forces, and if possible augment them by applying wing technology. The Aristo system 2017 version has air dams on the training edges of the vane blade, but they seem crudely designed and applied.

    There is a wealth of information about wing design, including airfoil shapes for low speed airfoils, light wing
    structure construction, airfoil controls and other things.

    My proposl is to build a simple vane support mechanism to attach to the pushpit of a sailing boat, in this case Arawana, supporting a symetrical airfoil vane blade, and using a gravity-activated gurney flap to augment the lift forces on the blade.

    The vane will be made up of a number of cedar airfoil secions, shaped to NACA 0012 symetrical airfoil shape. The airfoil shapes will be mounted at 100mm spacings onto two tubular spars of lightweight material. Expanded foam, hot-wire cut to profile, will by used to infil between the airfoil shapes. The airfoil will be covered in a plastic film, possibly mylar.

    At the trailing edge of the vane a pivoting flat blade will be mounted, for the whole span of the vane. A conterweight at each end of the vane, top and bottom, will swing under gravitational forces, to place a gurney flap of 2% to 4% of wing chord (to be determined by experiment) into the pressure side of the wing profile of the vane.

    References:
    Bill Belcher, Wind-Vane Self-Steering

    Gurney Flap
    https://en.wikipedia.org/wiki/Gurney_flap

    Aristo Timone a Vento http://www.aristotimone.it/

    Seems to me that this is more complex than something like a belcher servo pendulum unit. Or perhaps OGT attached to a small well balanced auxilary rudder. My old fleming major worked well on my folkboat, and it worked ok with the rudder locked and the servo rudder completely steering the boat. It is surprising how small a rudder will work if the boat is reasonably well balanced by the main rudder and sails beforehand. At any rate the first step to both is an OGT vane of some sort. Maybe you need the rest of Belchers book where he goes through all the theory?

  4. #3679
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    Quote Originally Posted by Snow Pea View Post
    Seems to me that this is more complex than something like a belcher servo pendulum unit. Or perhaps OGT attached to a small well balanced auxilary rudder. My old fleming major worked well on my folkboat, and it worked ok with the rudder locked and the servo rudder completely steering the boat. It is surprising how small a rudder will work if the boat is reasonably well balanced by the main rudder and sails beforehand. At any rate the first step to both is an OGT vane of some sort. Maybe you need the rest of Belchers book where he goes through all the theory?


    Not sure how you come to the conclusion that my proposal is more complex than a servo pendulum system. An OGT is a much simplified system compared to any of the rudder assist versions, as you obviously know. Swapping in an airfoil shaped blade in an OGT in lieu of a flat blade is a pretty small investment in effort to get a more efficient blade shape, I think, and as Belcher showed an OGT, even with a flat sheet vane, works on many small boats and almost works on many more.

    No doubt the Fleming worked well for you but I think you've missed my point, which is to simplify, reduce parts list, reduce weight hanging off the stern, reduce handling effort in heavy weather, reduce drag, increase efficiency. I'll hold for now that I should go read up again on the theory and I hope that when I have something physical to show, you and I will see whether I've achieved a relatively simple OGT system that works, or just complicated it. sorry if that sounds tetchy but I don't think I misunderstand the theory well, apart from the gurney flaps which may or may not work at the relatively low air speeds of a self steering wind vane.

    For my part, I accept that it's experimental and there's no guarantee it will work, and as you say if it doesn't at least I'll be half way to building a servo pendulum or aux rudder system anyway and nothing will be scrap.


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  5. #3680
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    Default Re: Voyages of Arawana

    Quote Originally Posted by Snow Pea View Post
    Seems to me that this is more complex than something like a belcher servo pendulum unit. Or perhaps OGT attached to a small well balanced auxilary rudder. My old fleming major worked well on my folkboat, and it worked ok with the rudder locked and the servo rudder completely steering the boat. It is surprising how small a rudder will work if the boat is reasonably well balanced by the main rudder and sails beforehand. At any rate the first step to both is an OGT vane of some sort. Maybe you need the rest of Belchers book where he goes through all the theory?
    That is the same design as the QME (?) I have...presently stored under the shed.
    The definition of stupid has got to be the belief that more guns will negate the bloodshed done with guns.

  6. #3681
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    Quote Originally Posted by WX View Post
    That is the same design as the QME (?) I have...presently stored under the shed.
    Yep, More or less the same design. The Belcher OGT has a few refinements but it works in the same way. A big horizonal axis vane direct to tiller.

  7. #3682
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    Quote Originally Posted by brucemoffatt View Post
    Not sure how you come to the conclusion that my proposal is more complex than a servo pendulum system. An OGT is a much simplified system compared to any of the rudder assist versions, as you obviously know. Swapping in an airfoil shaped blade in an OGT in lieu of a flat blade is a pretty small investment in effort to get a more efficient blade shape, I think, and as Belcher showed an OGT, even with a flat sheet vane, works on many small boats and almost works on many more.

    For my part, I accept that it's experimental and there's no guarantee it will work, and as you say if it doesn't at least I'll be half way to building a servo pendulum or aux rudder system anyway and nothing will be scrap.


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    I was a bit hasty and misinterpreted your concept, sorry. It seems, rereading belchers theory section that their may be a fair bit of benefit to having an airfoil section with gurney flap, maybe 30-50% more lift on some wind angles. Prehaps the same as increasing the height of a flat plywood vane by 15-20% or so.

    I will be very interested to hear how it goes. A reefable top section would be a good addition, or prehaps the gurney flap could be locked in line to depower it in stronger winds. And a big mylon extension added for lighter airs. Or maybe its simplerjust to have a few interchangable airvanes.

  8. #3683
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    Default Re: Voyages of Arawana

    Quote Originally Posted by Snow Pea View Post
    I was a bit hasty and misinterpreted your concept, sorry. It seems, rereading belchers theory section that their may be a fair bit of benefit to having an airfoil section with gurney flap, maybe 30-50% more lift on some wind angles. Prehaps the same as increasing the height of a flat plywood vane by 15-20% or so.

    I will be very interested to hear how it goes. A reefable top section would be a good addition, or prehaps the gurney flap could be locked in line to depower it in stronger winds. And a big mylon extension added for lighter airs. Or maybe its simplerjust to have a few interchangable airvanes.
    I suspect that I'll end up making a set of different sized vanes in an effort to try to make it work, so interchangeable vanes would likely be a natural product of pilot projecting it. I was thinking about that issue last night and I don't know that there's an easier workable way to reef the thing... that's supposing that it does work in practice. A quick release system should be reasonably easy to jigger up. I'd be happy to hear all suggestions on that. I suspect that a smallish vane would cover most conditions from beam reach to hard beat. Anything closer to a run would be another set of input conditions, and that's really the issue with sheet to tiller as well.
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  9. #3684
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    I understand the physics of a servo pendulum. In fact I think it is brilliant. But vane to tiller? I don't really have the faith.


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  10. #3685
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    Quote Originally Posted by Phil Y View Post
    I understand the physics of a servo pendulum. In fact I think it is brilliant. But vane to tiller? I don't really have the faith.


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    That's the thing about physics; it doesn't work based on the strength of someone's faith, otherwise I'd skip the design stage and go to church this week.

    You can see short clips of a couple of different versions of these in action on YouTube.


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  11. #3686
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    Default Re: Voyages of Arawana

    Yeah but that's just facts.

  12. #3687
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    Default Re: Voyages of Arawana

    I saw the clip you attached in a post above. Showed a happy dog on its owners lap while the boat presumably held course for about 2 minutes. Probably in ideal conditions. Seems to me the tilting of the vane can move the end of the tiller about 2 inches in either direction. That will maybe be useful,for some boats in a really small range of conditions. OK, I hope you prove me wrong, but my settled understanding is that vane to tiller never really worked, and for good and obvious reasons.

  13. #3688
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    Default Re: Voyages of Arawana

    Quote Originally Posted by Phil Y View Post
    I saw the clip you attached in a post above. Showed a happy dog on its owners lap while the boat presumably held course for about 2 minutes. Probably in ideal conditions. Seems to me the tilting of the vane can move the end of the tiller about 2 inches in either direction. That will maybe be useful,for some boats in a really small range of conditions. OK, I hope you prove me wrong, but my settled understanding is that vane to tiller never really worked, and for good and obvious reasons.
    I'm not going to do your homework for you, but if you're interested enough to post that vane to tiller never really worked you should look at the several clips from the same 'Aristo' guy on youtube, plus another user with a working system that looks like a Belcher OGT but with a tiny fabric vane. You should also read Belcher where he gives a list of boats of various sizes that the OGT system worked on, and his reasons why they worked on those boats and why they didn't/wouldn't on other boats.
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  14. #3689
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    Default Re: Voyages of Arawana

    No I'm going to stick with my ignorance until I see your system working. Then I'll be in awe. I know youve done your homework, so I'm sure there must be good examples of the system working well. It's like those questions such as is Junk rig better? People who love junk rig will swear blind that it's the best rig ever, does great on all points of sail and is simplicity itself. And will have books and videos to back them up. And sheet to tiller steering. And special magnets which save fuel and make your car go faster, while doubling your engine life. And electric hydraulic regenerating power systems on yachts. I just won't believe it until I see it. I dont know why I'm being all negative and trying to take the wind out of your sails. I think it's a great idea to have a go at building a simple and lightweight system. Best of luck.

  15. #3690
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    OK. Well thanks anyway for aligning me with all those other thing, especially the fuel magnets, but if you read my posts you'll see that I'm not actually advocating for anything, I do allow for OGT not working on Arawana and have a way or two forward in that outcome.


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  16. #3691
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  17. #3692
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    Bruce I have some spare stainless tube if you want it? It's some old seat frames removed from a bus one of my kids used as a bedroom for a while so it has various potentially useful bends and some angle sections. The tube might be a bit light. But that might be what you want. If it's not too light. Anyway welcome to it if you want.


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  18. #3693
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    Quote Originally Posted by Phil Y View Post
    Bruce I have some spare stainless tube if you want it? It's some old seat frames removed from a bus one of my kids used as a bedroom for a while so it has various potentially useful bends and some angle sections. The tube might be a bit light. But that might be what you want. If it's not too light. Anyway welcome to it if you want.


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    Yes please it will be very handy.


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  19. #3694
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    Default Re: Voyages of Arawana

    I'll try to remember to bring some down, Sheila will the thrilled I'm sure. I know Felicity always loves it when I bring useful things home.

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