Most Efficient Boat Propulsion

Discussion in 'Sterndrives' started by tom kane, Dec 4, 2014.

  1. whitepointer23

    whitepointer23 Previous Member

    What holds the drive down while moving forward . Does prop thrust do it and if so what holds it down for reverse. Is there some sort of lock like an outboard. I think cv joints would be better than unis or have you tried them.
     
  2. FMS
    Joined: Jul 2011
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    FMS Senior Member

    As far as I know there hasn't ever been a counter rotational surface drive for sale.
     
  3. tom kane
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    tom kane Senior Member

    The drive does not need to be locked down but you can lock it down if you wish. It is better unlocked because the drive trails behind the boat and can be deflected up easily if you strike shallows or a submerged object. Similar to a long tail boat drive.

    Because the prop is at a small angle the ascending blades keep the drive down and submerged.

    Two u/v joints with a sliding spline is a c/v joint. There are other designs.

    There looks like an opportunity for an International business supplying advice and parts for shaft drives.

    I forgot to mention that you can have a lift-able shaft drive for water jet propulsion and boat propulsion for wake riding fun. And helping the home handyman in DIY is high on our list.
     

    Attached Files:

    Last edited: Dec 13, 2014
  4. whitepointer23

    whitepointer23 Previous Member

    Thanks tom . So you didn't have any problems with it coming out of the water in reverse. Outboards are hopeless in reverse with out a tilt lock or hydraulics. With my old volvos I had to very gentle coming into a jetty because sometimes the reverse lock didn't engage and the bloody leg would pop out when you hit reverse.
     
  5. myark
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    myark Senior Member

    Hi Tom
    The pivotal Drive I am advancing does not have reverse built into the drive shaft as the same with the shaft drive ski boats we had when youths that had to turn the motor of while waiting for skier we to towed out of water, also had to be careful we did not damage the shaft on the boat ramp when placing on boat trailer.
    However with your design pivotal drive it does not have to turn motor of as you say, lift prop up manually above water or a simple leaver and keep motor idling
    For reverse there are several ways that can be added as in jet units but have other ideas to do this also even more simple and more effective and low cost.
    This allows direct power like the shaft drive skiing boat that was built for high performance.
     
  6. whitepointer23

    whitepointer23 Previous Member

    Can you use an east west engine with an auto. Weld.the diff solid and use one drive side. You would get your multiple gears in a compact package. If the whole system was compact and light it could be a bolt on retrofit for a stern drive or shaft drive. I don't think it would stick out any more than a pod and outboard.
     
  7. myark
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    myark Senior Member

    How much will that stabbing in the dark cost ?
     
  8. whitepointer23

    whitepointer23 Previous Member

    I don't know. I have never priced stabbing in the dark. Is that a real thing. Merry Christmas myark. Hope you have a great new year.
     
  9. myark
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    myark Senior Member

    Stabbing in the dark means ideas like "Weld.the diff solid and use one drive side." which is making a simple pivotal drive system very complicated that is not efficient to build and most likely unreliable "stab in the Dark thought"
     
  10. whitepointer23

    whitepointer23 Previous Member

    If you need a selection of gears as suggested by tom then using a front wheel drive engine and gearbox will need the least space. Not to expensive if using parts from a car wreckers. You need to weld the diff spiders which I am sure you know anyway.
     
  11. tom kane
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    tom kane Senior Member

    If you want it you can have it. Why not add "retractable" to that list and because rudders are not good at steering boats and create lots of drag invent some thing better.
     

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  12. tom kane
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    tom kane Senior Member

    The pivotal drive I used for shallow water had small twin rudders that worked similar to a kitchen rudder and swung more than full lock right or left and could turn the boat in it`s own length using the lifting lever up or down for more or less thrust. No need at all to use reverse.

    Rudders have a lot of disadvantages. I also tried having a second propeller behind the main prop working like a rudder but that was far to much drag.
     
  13. tom kane
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    tom kane Senior Member

    I would loved to have tried that idea more fully. There is a post of mine somewhere on this site using parts of a front wheel drive for a steerable retractable surface drive. I know someone who is a website member who is trying your suggestion.
     
  14. tom kane
    Joined: Nov 2003
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    tom kane Senior Member

    The attached image shows samsams post of lift-able drive more fully with
    the motor tilting with the drive which is not very practical for more powerful craft. This Patent was sited as a challenge (there were only two) to my Patent application but was recognized as having different aspects and it was unsuccessful as was the other Patent challenge.

    When lift-able or pivotal drives are discussed this drive is what is imagined by most people who do not know about other systems or know how such drives work.

    With Pivotal Drive you can fit the drive to a classic boat and not notice that is has a pivotal drive until you check up if you want to. I fitted one to a classic boat I was given for free and have since removed the drive and the boat was restored to original by replacing the transom post only.
     

    Attached Files:


  15. tom kane
    Joined: Nov 2003
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    tom kane Senior Member

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