Tanker proa

Discussion in 'Multihulls' started by Konstanty, Apr 18, 2016.

  1. rwatson
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  2. FrankB
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    Thanks for your interest - the sail design is the result of decades of design and testing and capable of changing direction 360 degrees.
     
  3. FrankB
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    2013 - Glad you asked - the testing was a success! Since then we have taken what we learned and further refined our patents. Currently we are identifying naval architects to assist in creating the plans for a full scale prototype.

    - Really enjoy your forum!
     
  4. rwatson
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    I recommend you investigate the Flettner thread.

    Huge sails on a tanker cant compete, as the number of actual vessels now using Flettner Rotors indicate.

    I will also make a prediction about what Naval Architects say about the Outrigger on a Tanker say.

    They will totally reject it.
     
  5. FrankB
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    Getting input from this forum is very valuable - what we are trying to do is unprecedented - we welcome all input + will take the sarcastic with the serious. Every game changing technology starts out as a crazy idea.
     
  6. FrankB
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    PS Flettner Rotors are very cool!!!
     
  7. Angélique
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    Angélique aka Angel (only by name)

    Hi Frank,


    [​IMG] - - - - - [​IMG]

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    (Just for clarity there's emphasizes on what's meant to be the main questions of this post.)

    Large ships are heavily flexing in heavy seas, so what happens to the in a severe storm heavily flexing tanker hull when she's hold firmly in the middle, by the aka (the cross beam) . . . ?

    And how does the aka survive such violence with a buoyant ama (the float) on the other end . . . ?

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    (Dutch spoken, but only a bit, it's about amazement over the ship's flex they're seeing)

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    at± 0:11 to 0:14 a really not so high wave, height ± 7~8 m (23'~26¼'), hits the ship.​


    the same ship in the same storm:inside,outside.


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    There's a max of five vids to show up per post here, so the next one is only a link to a vid by Emma Jane of the ship's flexing at the C deck on board the Cruise Ship MV Oceana on 19-03-2015, a short way out of Lisbon, when they hit a force 9 gale with 5 m (16½') swells, zoomed to the other end of the ship, so the flexing of the cruise ship is clearly visible.
     
    Last edited: Mar 29, 2018
  8. FrankB
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    In the case of the TankerProa the short length of the out rigger makes the tanker bow, stern and the outrigger assembly act like a three legged stool. The stresses imposed by the sea will only lift one leg of the stool while the assembly rotates about the line between the other two legs. The outrigger never imposes additional stresses on the hull of the tanker vessel that it would normally encounter without the outrigger.
     
  9. Angélique
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    Angélique aka Angel (only by name)

    That looks to me like you're talking about nice weather sailing there, but the sails are down in a severe storm I'll guess, since the ample engine power is far better equipped to handle the ship in these conditions.

    Then I'll think there's a lot of stress in the aka and the tanker's hull when the tanker rolls towards the ama, and the buoyant ama is pushed down, and also the tanker's hull can't freely flex when it's hold back in the middle, while flex is what keeps it in one piece.

    Also yawing of the tanker will give stress in the aka and in the vaka (the tanker's hull) when at the same time the tanker rolls towards the ama and so pushes the ama down, the tanker's yawing will then accelerate the temporarily submerged ama forwards and backwards.


    [​IMG]

    [​IMG]

    Since on large ships in heavy seas the bow and stern don't always roll at the same time in the same direction at the same quantity, there's besides the above illustrated movements also a lot of torsion movement in long vessels.

    In the above videos you see all these motions (in both pics) and including torsion movement combined, except for surge backwards if they keep enough engine power on, while on the tanker proa the ama sometimes is pushed down by the tanker's rolling towards that side, that's adding a lot of stress to whatever is connected to the ama, with the aka acting as a lever.
     
    Last edited: Mar 29, 2018
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  10. rwatson
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    The Ama's connecting girder will not be strong enough for big seas against the huge weight of the tanker, and in low sea states, the Ama will just add extra resistance and eat up fuel. Not to mention the problems of docking with a big increase in width.

    The big problem of sails, is that conventional sails DO require a counterbalance effect, but that freighter with the Flettner Rotors does not encounter that "capsize" tendency, as the thrust vector is fore and aft.

    The other big problem is the really low power supplied by conventional sails. Tests done with Kites (Lloyd Bergeson) showed the extra drive to be miserably small, and the effort of sail handling was a major problem.

    All this sail drive for commercial ships has been touted and tested for that last 30 years, and only the Rotors have advanced to actually being deployed as viable solutions, and then only for some routes.
     
  11. Angélique
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    Angélique aka Angel (only by name)

    It's the plan to anchor the outrigger (ama and aka) at sea when the tanker goes into port (see 1:23 to 1:32 in the video), the aka has extra floats for this on the vaka's side, so the whole outrigger can float independently, and the outrigger also has its own propulsion and steering system for the remarriage with the tanker when she returns from port.

     
    Last edited: Mar 29, 2018
  12. rwatson
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    I see.
    A detachable Ama is even worse.
    Imagine a dozen of these anchored further out in the Harbour. What a recipe for congestion.
    And, imagine detaching and re-attaching, especially in moderate wind or sea-state.

    I guess you would have to be in the industry to appreciate what a dopey concept it is in all.
     
  13. FrankB
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    Excellent point(s). We tested the TankerProa connected to the MMA(Massachusetts Maritime Academy) tanker of the same scale as the TankerProa, in waves crashing over the deck of the tanker and scale winds (in the opinion of the school's captain) that were equivalent to that of 100 mph wind and waves over deck on a full size tanker. There were no problems with the TankerProa or with the scaled tanker. The tanker vessel had a captain with experience on full size tankers, this was his expert opinion. Finally the polynesians used proa’s for thousand of years and populated all the islands in the Pacific.
     
  14. rwatson
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    Yeah BUT, what BENEFIT to the tanker in the Big seas ??
    What effect did it have on the steerage , the engine efficiency ?
    Why would they hang 50 tonnes of steel costing half a million dollars, off one side of the tanker in heavy weather?

    Comparing Proas to Tankers is really a non-starter

    Finally, Proas were developed due to limited natural resources and tools by the Polynesians. If they had the timber, and technology of the Europeans, it would only have taken them hundreds of year to colonise the Pacific, not thousands. Tankers are developed way past the simple concept of the Proas.
     

  15. rwatson
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    "In the case of the TankerProa the short length of the out rigger makes the tanker bow, stern and the outrigger assembly act like a three legged stool. The stresses imposed by the sea will only lift one leg of the stool while the assembly rotates about the line between the other two legs. The outrigger never imposes additional stresses on the hull of the tanker vessel that it would normally encounter without the outrigger."

    That just doesn't make sense.

    Imagine this wave coming in on the Ama side . The Ship would be inclined over by 5%, and huge strain on the freighter hull. Most ships are not designed to go past 7 degrees due to cargo constraints.

    SideWaves.jpg
     
    Last edited: Mar 31, 2018
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