Vertical Windmills...

Discussion in 'Boat Design' started by cstretten, May 26, 2007.

  1. cstretten
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    cstretten New Member

    (I posted this on another section of the forum... but thought it would be better suited in the Boat Design Section)

    Hey all... I'm not a boater... nor am I an engineer. Don't know much about the math involved in computing conservation of energy calculations either. I found this site when looking up sustainable wind energy... which led to an image of a windmill on a catamaran etc.
    I have since read a bunch of threads about this and that and the ability to travel against the wind... with the wind etc.
    Has anyone considered the idea of vertical windmills? They operate with wind from any direction, are quiet and work both as the wind enters and exits the turbine. These are usually used for power generation, but I don't see why you couldn't keep the power recharge capabilities for life on boat, and drive a prop for movement.

    I found an image on google of a catamaran and of a vertical windmill called a "Turby". I quickly put the two images together in Photoshop.
    Any boat designers/engineers here think that this could be a viable option?

    Image attached.
    Cheers,
    Chris
     

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  2. frosh
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    frosh Senior Member

    It does work!

    Hi Chris, I remember reading about an experimental yacht with a centrally located mast with many vertical slat like blades. When in the breeze the vertical blades which were all interconnected and in turn connected to the mast top and bottom by freely rotating sleeves, turned quite rapidly. Must have been around-20 years ago, or more. You could readily do a boat with multiple masts and turbine systems.
    There was a system at the base of the mast with geared wheels, a bit like the diff on a regular motor car, which went off to a shaft which then was something like a drive shaft on an inboard motor boat, fiinally ending up with a prop just under the water surface at the stern.
    This sailcraft could sail at any direction to the true wind and furthermore did not encounter much heeling force. It really does work in principle, and also has been proven in practice, but obviously has not caught on. You you would expect huge efficiency losses at the diff and we are not dealing with forces from the windmill that are very large compared to a marine diesel engine in the first place.
    A number of years ago when I was a serious motor cycle rider and technical enthusiast also, I studied the literature available on the relative cylinder configurations and drive systems for the bikes, and in conclusion to all this, the approx. efficiency losses in each different configuration.
    It is a no brainer to get the most efficient. Check out Moto GP bikes, as these had to be by definition, prototypes, and you wouldn't spend millions of $'s developing a bike that had more efficiency losses beween the engine crankshaft and the rear wheel than the absolute minimum possible known to engineering science.
    However the more interesting exercise was to examine cruiser type production bikes. The majority have a crankshaft aligned across the width of the bike, (going at right angles to the fore and aft axis of the bike). Drive was by O ringed metal chain connecting with a small sprocket at one end of the crankshaft, to a large sprocket connected into the hub of the rear wheel.
    This is as it is on a full on race machine. However a shaft driven bike has many advantages for the recreational rider which can be easily understood by most. (You could easily find out this stuff on the net) The real question then became how do you configure the cylinders to have shaft drive and retain the best percentage of the power at the crank, translating onto the road. The configuration chosen by Moto Guzzi was clearly superior to the one chosen by most of the Japanese bike manufacturers. The simple summary is that the Moto Guzzi had only a gearbox behind the crankshaft, and one diff on the hub of the rear wheel. The Japanese bikes with shaft drive had a gearbox at the side of the motor crankshaft, a forward diff, a shaft running back to the rear wheel, and then a second diff, at the rear wheel.
    The Japanese being very technically ingenious, sought to overcome the inherent greater efficiency losses, by designing engines with significantly better specific horsepower per cc of engine capacity.
    The answer coming back to a wind driven boat was that if point to point speed was important, then the turbine driven sail system simply sucked.
     
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  3. Pericles
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    Pericles Senior Member

    The output from the vertical turbine drives an alternator, then use the electricity for propulsion. That's the principle. Who can do the maths please?:D

    Pericles
     
  4. Poida
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    Poida Senior Member

    I'm definately not a geek and can't do the maths. But energy would be better going direct and cutting out the middle man.

    A sail driven boat would have to go faster as any conversion of the wind power into electrical energy and then through shafts and a propellor as I think you suggest would consume power (friction)

    I can't see anybody wasting their time doing the maths.

    Poida
     
  5. westlawn5554X
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    westlawn5554X STUDENT

    Anybody watched waterworld film... I think it is an old idea that might work...:)
     
  6. yipster
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    yipster designer

    Jacques Cousteau try'd another type but a windmill like above we had near a lake that was replaced with a normal prop covering twice the area. Malcolm tennant proposes one on his biggest boat also but motion, sound, reefing and other factors may not make it the best rig yet..
     
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  7. westlawn5554X
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    westlawn5554X STUDENT

    Seen that... many of documentary with that boat... vertical wings... I think the boat is now scape. :(
     
  8. rob denney
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    rob denney Senior Member

    G'day,

    I designed and built a 9.2m/31' 3 bladed horizontal axis turbine for a 9m cat a few years ago. Power was through a right angle gear box at the mast head, drive shaft to another right angle at the base and then to a 1m dia water prop. Worked pretty well, max was 6 knots directly into 20 knots of breeze, much better vmg than under sails. This was at about 110 rpm. It was designed to turn at 180, so there was plenty more power available.

    Part of the design process was to check out vertical axis turbines. They are superior in almost every aspect(ease of build, control, etc), except efficiency. Can't remember the exact numbers, but a va machine would struggle to proceed directly into the breeze. Adding a generator and electric motor kills both types stone dead.


    regards,

    Rob
     

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  9. frosh
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    frosh Senior Member

    Too many gearboxes.

    Hi Rob get the cool DRIFTER. That name has a double entendre, don't you think?
    http://www.kawasaki-drifter.info/
    It also has efficiency losing gearboxes at each end. You mention speed up to 6 knots directly into a fairly strong wind, and I estimate maybe 8 knots downwind allowing for windage acting on the hull in a favourable direction. VMG around a triangular course is well below what could be achieved with a mainsail only.
    Imagine if we run main, jib and kite off the wind. WE might double the average speed around a triangular course. This alone would mean that this system would not catch on for small boats. It would be competitive for massive oil burning ships , in running costs, if you had a huge bank of them. Thats money and windmills!' :p
     
  10. Leo Lazauskas
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    Leo Lazauskas Senior Member

    There is a bibliography related to Vertical Axis Wind Turbines (VAWT) at:
    http://www.cyberiad.net/vawtbib.htm

    I thought that an interesting variation would be a pair of VAWTs rotating in opposite directions and driving Voith-Schneider props, which are just the water version of VAWT. There should be no need for any transmission losses if the devices are well-matched.

    There are certainly lots of opportunities for amateur engineers to get their fingers caught in high-speed machinery!

    Have fun,
    Leo.
     
  11. Pericles
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    Pericles Senior Member

    Whoa guys, including Poida

    The vertical windmill delivers power from the wind from any direction, which means that generating electricity enables the boat to drive straight upwind. Somehow, I do not think that is possible with sails, but I wait to be convinced.:D :D :D


    Pericles
     
  12. frosh
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    frosh Senior Member

    Consider the simple physics!

    Hi Pericles, Of course it is possible for a sailing boat to sail directly into the wind. The only proviso is simply that any sort of conventional sail(s), either ancient or the most modern, and everything in between is incapable of doing so.
    A little bit of lateral thinking takes one to the path of NOT generating electricity to drive an electric motor, but the the more sensible alternative which has been proven in REAL experimental boats a number of times in actual sailing tests. The one described by Rob Denney in his post a few back is real, and there is no electricity being generated here.
    Unfortunately I have been unable to find a reference and photo on the net of a vertical axis windmill, hooked up by one gearbox and shaft to a large underwater prop, but that has DEFINITELY been done succesfully.
    The principle is simply that we are not using a sail as a wing as in an aircraft but using sail like blades to rotate in a breeze, around a shaft, either set horizontally, or vertically, (either can be made to work). Then by purely mechanical liinkages a shaft is rotated that terminates in a propeller at the stern of the hull which is rotated using the energy generated by the wind energy turning the sail turbine.
    The whole point of this discussion as I see it is not whether it is possible, but is it too inefficient to be worth pursuing with further refinements?
    I hope that (1) this a simple easily understood explanation, and (2) I haven't got any of the physics wrong. Please some-one like Leo Lazauskas, (or other academically qualified person in this area), make a comment on this posting, regarding the physics and the logic contained here-in.
    I am not too proud to stand corrected.
    Regards to all, Sam
     
  13. erik818
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    erik818 Senior Member

    Hi,
    I think electical transmission from the windmill to the propeller has not been given a fair trial. I have some knowledge of electrical drives in land vehicles. A correctly designed electrical transmission has an efficiency of approximately 80%, measured from the generator input shaft to the electrical motor output shaft. A straight shaft plus a simple gearbox would have close to 100% efficiency, so going for electrical transmission means a 20% loss. (An electrical transmission dimensioned by a novice in the field,and possibly put together of easily available parts, can of course have higher losses.)
    Electrical drives make maximum torque at low rotation speeds possible. It isn't neccessary with propeller slip to get maximum torque at low speeds, allowing for smaller propeller losses.
    The drawbacks with electrical transmission, apart from the 20% loss, are cost, weight and complexity.
    Electrical transmission is more flexible than mechanical transmissions, e.g. when adding power from different sources, so using it on windmill-powered boats seems resonable to me. If you want a windmill-powered boat.
    Erik
     
  14. Pericles
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    Pericles Senior Member

    Frosh wrote this.

    "Hi Pericles, Of course it is possible for a sailing boat to sail directly into the wind. The only proviso is simply that any sort of conventional sail(s), either ancient or the most modern, and everything in between is incapable of doing so."

    Which I understand to mean nobody has done it yet. Physics win again. Unless Frosh really has something we should all see.

    Pericles
     

  15. frosh
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    frosh Senior Member

    Very clever, almost!

    Hi Pericles, this is my EXACT first sentence that I made in my previous posting.
    " Hi Pericles, Of course it is possible for a sailing boat to sail directly into the wind. The only proviso is simply that any sort of conventional sail(s), either ancient or the most modern, and everything in between is incapable of doing so".

    This is your supposed verbatim QUOTE of what I said as in your last posting.

    "Hi Pericles, Of course it is possible for a sailing boat to sail directly into the wind. The only proviso is simply that any sort of conventional sail(s), either ancient or the most modern, and everything in between is incapable of doing so."

    I examined this carefully to see where you may have altered anything, but was at a loss; it was identical; then the penny dropped.

    The KEY is the use of the word I put in " Conventional".
    Makes all the difference, wouldn't you agree?
     
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