Fin Drive and Stabilization

Discussion in 'Pod Drives' started by Boston, Jun 4, 2012.

  1. Boston

    Boston Previous Member

    I thought I'd try and bring our fin drive experts to discuss the mechanics and efficiency of fin drive systems.

    For the sake of neutrality I'll call it Fin Drive

    Lets see if we can keep at least just one thread reasonably on track

    Sudorra
    Swashdrive
    Kjell

    lets try that again without the interruptions, the suggestion that 87% efficiency "has" already been attained is a fantastic achievement, certainly blows away the prop world with a cheap and simple drive system.

    I realize there's patent issues going on here, which will have to be resolved elsewhere but all in all its a great idea, well worthy of further discussion.

    I might suggest preliminary patents
     
  2. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    Can you provide us an idea of what you mean by a fin drive. Not sure if that is a surface drive or simply a fish fin paddle drive
     
  3. Boston

    Boston Previous Member

  4. kjell
    Joined: Aug 2005
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    kjell Senior Member

    FIN-DRIVES.
    For me the definition FIN-DRIVES means oscillating marine propulsion.
    There are 2 types of FIN-DRIVES movements.

    1 FANNING. THE DORSAL TAIL MOVEMENT.

    2 FAN-FLAPPING. THE PECTORAL FIN MOVEMENT.
     
  5. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    Interesting, I did not think a boat with fins could go that fast. It seems much more complicated to build than a standard drive. Nature gets away with it because of use of linear type muscles designed to flap lengthwise. A liner motor can attain great speed and force, perhaps one can be use to move flippers.
     
  6. Boston

    Boston Previous Member

    I was envisioning two pairs, one on each hull of a power catamaran. Displacement speeds only. So going slow the viscous resistance is low and the efficiency high, pitch and angle can be optimized for the slower speed. the fins look a lot cheaper than props and although the mechanism is not set in stone yet, it seems like it would be easy to flip the drive fins up for shallow water.
     
  7. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    I think a whale tail more efficient and easier to move. Draft would not be issue because fin could be longer and bigger. Either way vertical or horizontal a bit of motion would be moved to hull. So you need to compensate for it.
     
  8. Boston

    Boston Previous Member

    well the fins are arranged in a pair of equal and opposite forces, so the adverse motions are canceled

    in the end its two whale fins, working in tandem.
     
  9. swashdrive
    Joined: May 2012
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    swashdrive Junior Member

    Heah Boston

    Good idea, i just hope those that like to argue stay away or resist the urge to ridicule cause they don't understand or don't want to !
    Not going tall poppy here, but my fin drive really is the first real successful unit I've seen that can get up on the plane and do what a prop does !
    So i think to stop arguments lets not state any efficiency or its stature over a prop or the same will happen here !
    regards
    Craig
    Swashdrive™
     
  10. spork

    spork Previous Member


    You must be referring to statements like this:

     
  11. swashdrive
    Joined: May 2012
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    swashdrive Junior Member

    So whats the deal ?

    You gonna shot me down here too ?
     
  12. Boston

    Boston Previous Member

    wasn't my idea about the fin arrangement, I'm just trying to follow the thread through all the interruptions. Be it a vertical or horizontal arrangement, its you guys all the way. And its really quite impressive, ok so even if we leave off the exact efficiency claims, it does seem to work. I'm just curious if it works a well at slower speeds.
     
  13. spork

    spork Previous Member

    I haven't shot you down anywhere. I asked and answered some questions. For some bizarre reason you claimed that I "don't get it".
     
  14. Boat Design Net Moderator
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    Boat Design Net Moderator Moderator

    <multiple posts between the same two people fighting with eachother have been deleted>
    Please, let's keep the forum discussions polite. If you only want to rehash a year old argument or toss insults or namecalling at the same person (again), please take it to some other site. Or if someone really bothers you, please put them on your ignore list.
     

  15. kjell
    Joined: Aug 2005
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    kjell Senior Member

    Horizontal Tail Drive.
    This is my latest designs. In upper and lower position the tail is lined to the water flow.
    Attached Thumbnails
     

    Attached Files:

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