Sailors wrong for thousands of years?

Discussion in 'Sailboats' started by backyardbil, Feb 7, 2011.

  1. Windmaster
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    Windmaster Senior Member

    Thanks for your opinion which you have mentioned several times, it has been noted.
     
  2. BATAAN
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    BATAAN Senior Member

    Sounds like you are addressing the problems with creativity and common sense.
     
  3. CutOnce

    CutOnce Previous Member

    Sounds really interesting. At the end of the day, the real question to me is how VMG works out best - is the upwind speed better going straight upwind with the rotor, or can a boat tacking at 45 degrees get better results, even though the distance traveled is longer.

    Once the results of VMG testing are established across a variety of expected conditions, then you could do a subjective "value" assessment - is a X% VMG improvement worth spending Y% more money, or is it just fun enough to bend minds in the yacht club that the money is irrelevant.

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    CutOnce
     
  4. Windmaster
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    Windmaster Senior Member

    Even if the VMG is inferior or equal, there are circumstances where it is useful to go directly upwind, such as in rivers with little room to tack or in crowded harbours.
    Also, the ability of "hover" and standstill against the wind. You could let it run all night and thus relieve or eliminate the pull on your anchor chain! After all, you're not using any fuel. It might also be useful to attach a generator and charge you batteries whilst doing this!
     
  5. CutOnce

    CutOnce Previous Member

    I've got to say there have been a few times going through crowded mooring minefields in boats without auxiliary power I wished straight upwind was possible - and performance wasn't important. Might cut down on global Rogaine expenses!

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    CutOnce
     
  6. BATAAN
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    BATAAN Senior Member

    The ability to hover and move sideways and backwards with equal power is one of the wonderful things about the vertical vane tug drives now in wide use. Also jet drives are very well developed and controllable, though require a lot of power to be effective.
    If the wind power could be used to utilize either one of these, or an azimuthing 360 degree propeller pod with controllable pitch, the versatility would start to look tempting to possible commercial users like say small scale ferry or water taxi operations where the seas are generally protected and the winds steady and predictable, though adverse.
    The enclosed photo shows a rube goldberg azimuthing drive we designed, built from trolling motors, delivered and operated in a 3 day weekend for a big Hollywood production.
    At 36 volts it was very powerful and it's intriguing to consider adapting the idea to wind power and instead of one large heavy expensive wind prop, something like a bank of small wind generators on a controllable frame.
    This would be, for the boat shown, 12 of the small diameter, multi-blade, fairly low output wind gens that are widely used by sailboats and remote locations worldwide, mounted on a trunnioned frame that could azimuth 360 as well as swinging horizontal above your head with the blades up to safely reef or reduce area, looking much like a big bedspring hung in a giant oarlock, plus a battery bank for ballast.....
     

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  7. sharpii2
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    sharpii2 Senior Member

    I think one of the Herreshoft brothers experimented with this idea.

    Yes it did work.

    No it wasn't significantly better than any of the sail boats of their era.

    Scaled up, it is complicated and has at least one very dangerous moving part. The windmill. Which has to be light and large, if stability concerns are to be taken into account, which generally translates to being fragile.

    Also, if sailing any direction other than up wind, its performance sucks (and maybe even then, compared to a more modern keel boat tacking).

    Sailboats were not originally designed to sail primarily up wind. That became a fetish once better aerodynamics and better material science met club racing.

    On just about any equilateral triangular course, the boat that sails up wind the best is most likely to win the race. Especially if it's allowed to field an enormous down wind sail, like today's racing sailboats are.

    Even the ridiculous trimaran in the movie "Water World" reverted back to sail when it was time for it to move on.
     
  8. backyardbil
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    backyardbil Junior Member


    How do you know all this? Would be interested to hear where you got the information on the trials that indicated it was not better than other sailboats of the era. Perhaps you can point to a website or book? Also, where can we find out about the ones that failed because they were too fragile?
    (Or is this just your opinion without evidence that you are putting forward as fact?)
    Suggest you come back with more informed comments when you have studied the evidence on Windmaster's website - (which you obviously have not done yet).
     
  9. sharpii2
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    sharpii2 Senior Member

    You are right, of course.

    I have not given any annotation and I probably should have chosen my words better.

    This has been tried several times that I have heard of, but I don't see any of them sailing around.

    Bataan brought up an interesting point. Such a system might be useful in certain specialized applications.

    But as for replacing straight sailboats, I just don't see it. And, by the title of this thread, I was taken to believe that that was what this is all about.

    The blades on the windmill have to be featherable or retractable too. More expense and complication. Farm windmills are designed to fold in strong winds, so the blades don't over spin or get bent backward. Wind turbines feather their blades in rising wind for the same reason.

    Even if it did go up wind better than a modern sloop of the same cost and complexity, it's an even bet that it will be inferior on other points of sail. This may be for no other reason than its easier to increase sail area than it is to increase blade area. And the center of the blade area will most likely be considerably higher as well. And, most likely, so too will the center of gravity of the system.

    I will be more than happy to be proven wrong on this.
    I never learned a thing from an argument I won.
     
  10. Windmaster
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    Windmaster Senior Member

    Despite the title of the thread, we did mention earlier that they might not be suitable in all conditions and that everything has its limitations.
    Also, on the point about being good upwind but being poor on other points I made the suggestion of a dual-drive system in post #74.

    As for being complicated.
    How many moving parts? We gladly accept engines which have many more moving parts than this and are much more complicated.

    Nobody suggests that they could replace conventional sailing.
    As new technologies emerge its usual to find that they run alongside the earlier technology. For example:
    Cars didn't replace trains.
    TV didn't replace films.
    Motorcycles didn't replace pedal cycles.
    The list goes on......
    For some reason many people think in black and white terms of "one thing or the other".
    Instead of "one thing AND the other".
     
  11. A.T.
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    A.T. Junior Member

    It has nothing to do with the density difference between water and air. It would work in two fluids of equal density as well.
     
  12. jehardiman
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    jehardiman Senior Member

    Setting aside the issue of fluid mixing between two fluids of the same density, I would like to note I was commenting on the OP's single shaft design where the rotor and prop share a constant rpm and equal torque.

    In the case of real fluids of equal density (and similiar viscosities) you cannot have any "upwind" work with that device because you can't exploit the differences in disk torque to disk momentum, i.e. loses in induced drag will always be greater than the thrust because the propulsor wheel must always be smaller/less pitch to allow for net torque which always means that net upwind thrust will be negative. This is not true in fluids of different density and similiar viscosity, like water and air. In the water and air case, the water disk can be significantly smaller and therefore have the same torque at a given rpm than the air disk but have greater disk momentum and therefor generate "upwind" thrust. On the other hand, if I have fluids of the same density and different viscosities, I run into significantly more problems because viscosity is always a loss and I will never be able to recover my induced drag.

    I'd need to do some thinking and the math, but I'm pretty sure that in any real system (including vertical rotors) using fluids of equal density (asuming like viscosities and one "layer" is moving and the other is not) you still would not be able to generate a net "upwind thrust" due to induced drag issues on the rotor and prop.
     
  13. Windmaster
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    Windmaster Senior Member

    How about if the fluids were solids? Are you saying that it is impossible for anything to proceed in the opposite direction to the force driving it?
    Also, the op didn't design the single shaft version, I did.
     
    Last edited: Apr 12, 2011
  14. Dave Gudeman
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    Dave Gudeman Senior Member

    Are you saying that you designed a boat with a vertical-axis turbine and a vertical-axis propeller on the same vertical shaft? I missed that. Do you have a link to it?
     

  15. Windmaster
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    Windmaster Senior Member

    No, it's not vertical - he means the one here http://www.sailwings.net/windspinner.html
     
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