1. Joined
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    26 Jun '16 12:113 edits
    Here is a physical puzzle I thought up but I don't know what's the answer to it;

    As surely most people would know, the way a conventional sailing ship is able to sail again the wind when the wind is, say, blowing exactly southwards when the ship is required to move exactly northwards, is in a zigzag pattern because it cannot sustainable move directly exactly northwards but at an angle to northwards hence the need to zigzag.

    But what if, instead of having a sail on the wind powered ship, we place a wind turbine on it to convert some of the wind energy into electric energy.
    And we also put a water propeller (just like on most conventional modern ships) at the back of the ship to push it forward but this water propeller is entirely powered by an electric motor that in turn gets all of its electricity from the wind turbine. Lets say both the electric motor for the water propeller and the electric generator of the wind turbine is 99.9% energy efficient so there is negligible lose of energy there.
    So would such a wind turbine ship be able to sustainable move directly exactly northwards against an exactly southward blowing wind without zigzagging?
    Or, if you tried that without zigzagging, would the backward force of the wind turbine blades exerted by the wind against it be greater than the forward force exerted by the water propeller at the back of the ship thus you would still have to zigzag?

    I don't know how to work this one out.
  2. Cape Town
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    26 Jun '16 13:19
    My gut feel is that it would be able to head into the wind. I am certain that a land vehicle would be able to do so.
  3. Cape Town
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    26 Jun '16 13:25
    This Wikipedia page suggests it works, but the references to actual ships end in suspicious dead ends claiming there are secrets involved.
    https://en.wikipedia.org/wiki/Windmill_ship

    http://www.boatdesign.net/forums/projects-proposals/windmill-wind-turbine-powered-boats-how-many-out-there-they-viable-14182-4.html
  4. Cape Town
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    26 Jun '16 13:32
    Also of interest:
    YouTube

    http://www.sailwings.net/windspinner.html

    Would be relatively easy to build one to test for yourself.
  5. Cape Town
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    26 Jun '16 13:38
    Because of the way blades work, I believe a turbine and propeller is equivalent to tacking into the wind ie the wind pushes the turbine propeller sideways the same way it does with a sail, and the propeller pushes water propelling the boat forward the same way a keel pushes a tacking boat forward.
  6. Cape Town
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    26 Jun '16 13:44
    A claimed actual turbine powered catamaran- the Revelation II. Not sure if it is real, but there are multiple photos of it:
    http://www.treehugger.com/renewable-energy/windmill-sailboat-sailing-against-the-wind.html
    http://www.shipspotting.com/gallery/photo.php?lid=1881693
    http://www.shipspotting.com/gallery/photo.php?lid=1881690
  7. Joined
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    26 Jun '16 16:515 edits
    Originally posted by twhitehead
    My gut feel is that it would be able to head into the wind. I am certain that a land vehicle would be able to do so.
    I had no idea this idea had not only been thought of before (hence I didn't even try to google it ) but they gave it exactly the same name (windmill ship) I did!

    I just read your link and found it said;

    https://en.wikipedia.org/wiki/Windmill_ship
    "...
    Points of sail
    Because a windmill can rotate 360° into the wind, no matter what direction the ship is facing, a windmill ship can sail in any direction. In fact, because the power produced depends almost entirely on the apparent wind, they can produce the most power sailing directly upwind.[2][3] Note that sailing upwind, while resulting in more power generation by the wind turbine, requires more power to be expended by the engine and thus it is still more efficient to sail down wind. To sail upwind, a conventional sailing vessel must tack across the wind.
    ..."

    And, although doesn't directly state this point, I am sure that it implies the answer to my OP question is "yes", a windmill ship CAN sustainable move in the exact opposite direction to that of the direction of the wind i.e. WITHOUT zigzagging.
    I cannot see any other possible way of interpreting the above quote from that link.
    So I take it there is nothing in physics that implies that idea cannot work.

    Thanks for that!
    If only I had googled "windmill ship" I wouldn't have started this thread.
    'Good' news; my idea works. 'Bad' news; its nothing new.
  8. Joined
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    26 Jun '16 17:563 edits
    I found this;

    http://blog.modernmechanix.com/wind-propeller-sails-proposed-for-liners/

    "...A working model of the windmill ship was on demonstration at the Inventions Exhibition sponsored by the Institute of Patentees at Westminster, England.

    Since the propeller could face into the wind regardless of the direction the ship is traveling, it is believed highly probable that windmill boats could travel directly into the wind.
    ..."

    http://www.treehugger.com/renewable-energy/windmill-sailboat-sailing-against-the-wind.html
    "...
    The 36 foot catamaran, Revelation II, is powered by 3 20-foot long carbon fiber propellers on a 30 foot rotating mast. The windmill transmits power to a 6 blade propeller underwater, with the net result that the boat can make way even directly into the wind.
    ..."

    and take a look at a photo of one at:
    http://news.bbc.co.uk/1/hi/uk/1507825.stm

    So I take it this has already been experimentally demonstrated? -the links I have got don't seem to make this completely clear.
  9. Cape Town
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    26 Jun '16 18:132 edits
    Originally posted by humy
    Thanks for that!
    If only I had googled "windmill ship" I wouldn't have started this thread.
    'Good' news; my idea works. 'Bad' news; its nothing new.
    Not everything on Wikipedia is automatically true. I have failed to find conclusive evidence that it works. The best so far is the video of a working model - although I cannot tell if it actually does work straight into the wind.

    You didn't seriously think you were the first to think of it?
    Here is the 1935 version:
    http://www.treehugger.com/cars/wayback-machine-1935-wind-turbines-on-ships.html

    Land vehicle concepts:
    YouTube
    http://www.energy-today.biz/history-reminder-first-wind-powered-car-inventus-ventomobile/

    Just for fun, but not actually a wind powered car:
    http://www.autoevolution.com/news/mitsubishi-pajero-powered-by-wind-turbine-surfaces-in-romania-video-83241.html

    Wind turbines and solar panel being used to generate power on a ship (not for propulsion).
    YouTube

    Not quite, but they nearly had the idea in 1902:
    https://en.wikipedia.org/wiki/File: Sailing_ship_Chance,_aground_at_Bluff,_1902.jpg
    (remove space from link to make it work. I had to add the space to avoid smilies)
  10. Joined
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    26 Jun '16 21:046 edits
    Originally posted by twhitehead

    Just for fun, but not actually a wind powered car:
    http://www.autoevolution.com/news/mitsubishi-pajero-powered-by-wind-turbine-surfaces-in-romania-video-83241.html
    hell, that looks dangerous! I think that is a none starter of an idea for safety reasons unless they make the turbine blades suspended much higher up so there is no risk of chopping up pedestrians; -but then you must be careful to not make it so high up that it would hit high voltage overhead electric cables or bridges etc. Even then, in the event of a car crash, there would be the added danger of the spinning blades coming crashing down on people with the possibility of a decapitation. I think it probably be just too problematic.
  11. Standard memberDeepThought
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    26 Jun '16 22:53
    Originally posted by humy
    hell, that looks dangerous! I think that is a none starter of an idea for safety reasons unless they make the turbine blades suspended much higher up so there is no risk of chopping up pedestrians; -but then you must be careful to not make it so high up that it would hit high voltage overhead electric cables or bridges etc. Even then, in the event of a car cras ...[text shortened]... n on people with the possibility of a decapitation. I think it probably be just too problematic.
    Will the windmill generate enough power when travelling directly into the wind to compensate for the way the wind is pushing the rest of the ship backwards - assuming the turbine is smaller than the forward profile of the rest of the ship?
  12. Joined
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    27 Jun '16 06:06
    Originally posted by DeepThought
    Will the windmill generate enough power when travelling directly into the wind to compensate for the way the wind is pushing the rest of the ship backwards - assuming the turbine is smaller than the forward profile of the rest of the ship?
    from what I can gather from reading the various links, at least in theory, yes!
    I presume it would greatly help if the whole ship is designed to be as aerodynamic as possible.
  13. Cape Town
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    27 Jun '16 07:28
    Originally posted by DeepThought
    Will the windmill generate enough power when travelling directly into the wind to compensate for the way the wind is pushing the rest of the ship backwards - assuming the turbine is smaller than the forward profile of the rest of the ship?
    I think the question here is how a sail compares to a turbine when it comes to wind power efficiency - or rather how the forward profile compares to a turbine. Just like sailing ships, for the idea to have any real use, I suspect the turbine would have to be very large in relation to the ship and so would be unwieldy. Sails just make more sense. Sails should really be used more even on large container ships they can make significant fuel savings and since shipping is a large contributor to pollution, this should be encouraged.
  14. Standard memberDeepThought
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    27 Jun '16 19:33
    Originally posted by twhitehead
    I think the question here is how a sail compares to a turbine when it comes to wind power efficiency - or rather how the forward profile compares to a turbine. Just like sailing ships, for the idea to have any real use, I suspect the turbine would have to be very large in relation to the ship and so would be unwieldy. Sails just make more sense. Sails sho ...[text shortened]... fuel savings and since shipping is a large contributor to pollution, this should be encouraged.
    If the idea is to be able to sail directly into the wind, without tacking, then sails won't do. Sails will be more effective than a windmill when sailing with the wind, because they can capture a larger area of wind, I don't envisage any advantage to having a windmill except when sailing into the wind, and then tacking in a sailing ship is still better. More useful would be a sailing ship with solar power as a backup for when the ship is in the doldrums.

    Large container ships are just too big for sails. I used to know someone who worked on the Golden Hind (or rather its reproduction), he knows about sailing but not engineering so much. I suggested this to him and his response was that it wouldn't work and couldn't be made to, as the masts could never be made strong enough. Like I said, he's a sailor and not an engineer so he could be wrong, but he's liable to either be right or right enough that the investment needed to get it to work is too much (and better spend on carbon mitigation elsewhere).
  15. Subscribersonhouse
    Fast and Curious
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    28 Jun '16 00:16
    Originally posted by twhitehead
    I think the question here is how a sail compares to a turbine when it comes to wind power efficiency - or rather how the forward profile compares to a turbine. Just like sailing ships, for the idea to have any real use, I suspect the turbine would have to be very large in relation to the ship and so would be unwieldy. Sails just make more sense. Sails sho ...[text shortened]... fuel savings and since shipping is a large contributor to pollution, this should be encouraged.
    That was my thought, Is it worth it? It would be interesting to build two Cat's same size and weight, one with props the other traditional sails and see which one can go the fastest or the furthest or in the least amount of wind or taking directly into the wind and so forth.

    My guess is the traditional sail would beat out a prop which has unavoidable drag in the transmissions and such, you would have to have a transmission of some kind even if it was powering a generator since a generator has a certain max efficiency at some RPM and would lose efficiency above and below that and since a prop would have a very wide range of RPM's it would have to be coupled the most efficient way to hit the most efficient RPM range of a generator or in the case of a direct drive to an underwater prop like they talked about, also some kind of transmission that would keep the prop at its best RPM for the speed and so forth. My guess is a traditional sail would ultimately beat it out in terms of tacking to the wind and the lowest wind speed and all that.

    I bet you would lose 20 or 30 percent of your energy on the way from the prop to the rest of the system, however you couple that power due to friction and drag and so forth, inherent in physical transmission systems.

    Of course on very rare occasions I have been known to be wrong🙂
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