Paddle boat Tri Hull

Discussion in 'Boat Design' started by LowelandSystem, Sep 19, 2016.

  1. LowelandSystem
    Joined: Nov 2015
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    LowelandSystem Junior Member

    Hello guys, I have designed a 4 seater paddle which I have to deliver within 2 months time. its 6 ft wide, 3 ft tall and 10ft long. Looking for feedback. Thank you.
    I have attached the pic of the design outlook .
     

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  2. Rurudyne
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    Rurudyne Senior Member

    I'm curious about the perceived benefits of the hull arrangement over a barge form, which would be much simpler to build?
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    That is the obvious question, for sure. Answer would appear to be no benefit at all.
     
  4. PAR
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    PAR Yacht Designer/Builder

    I see a lot of drag associated with this hull, particularly if the crew is peddling it. A garvey, jon or even a barge like hull form would be much easier to build and to propel.
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    I see a lot of unnecessary work, to no good end ! Invoke the KISS principle Mr OP !
     
  6. sharpii2
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    sharpii2 Senior Member

    A catamaran hull might be better, if not a scow.

    The two advantages of a catamaran hull are:

    1.) the padlle wheel can be between them, and
    2.) the two hulls will be easierto build with sufficient stiffness than a single flat bottom one.

    One very noticeable problem with your design is that immersed transom.

    Such is only good for planing boats.

    Since this boat is going to be presumably powered by people, its not going to have anywhere near enough power to plane.

    The rear transom must be clear of the water, even when the boat is fully loaded, if it's to perform reasonably well for the amount of power it's likely to have. You must work in enough displacement to make this so.

    If this is not possible (I noticed seating for four people) there are two dodges you can use:

    1.) you can make the aft end of the hulls pointed, with the taper starting at one Hull width from the stern (you can do the same with the bow, BTW), and

    2.) you can have the transoms immerse only a portion of the boat's fully loaded Hull draft, so they might be clear of the water, with two aboard, but immersed with four aboard.

    To make this possible, you are probably going to have to change the seating arrangement. The aft seats are going to have to face aft, in order to get the boat to trim reasonabaly well, with crew sizes ranging from 1 to 4.

    The funny thing about this boat type is that the hull shape can probably be drawn easier on a napkin than with hull design software. The reason for this is you're always fighting to get sufficient displacement volume. And the fair curves, most hull design soft ware apps like to draw, just won't get it
     
  7. LowelandSystem
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    LowelandSystem Junior Member

    Thanks a lot guys, I will show you the picture of the main boat which I have with double hull, which was top heavy and center of gravity was shifting rapidly, so I have planned to cut single part hull and put a third big hull in the middle to correct the mistake. It was for a client, but due to some error we have to bring back the boat.
     
  8. daiquiri
    Joined: May 2004
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    daiquiri Engineering and Design

    Hi Loweland,
    as others have pointed out, you have made a constructively more complicated and draggy central hull than what appears to be necessary.
    IMO, the following modification would be simpler, less costly and hydrodynamically better solution:
    Paddle-mod.jpg
    unless, of course, there are some particular and sound reasons why it cannot be done this way.

    Cheers
     
  9. LowelandSystem
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    LowelandSystem Junior Member

    Wow Daquiri, thanks a lot, am in debt to you. Any help if I could offer to you. Thanks again for the correction. kind regards.
     
  10. messabout
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    messabout Senior Member

    As Sharpie II wrote, the transoms will drag and that is a disadvantage for a human powered or other displacement type vessel. Put some rocker in the bottom as it approaches the transom. That is to say, get the transom at or above the waterline when the boat is Fully loaded. You will need to re-calculate the displacement and/or draft figures when you do.
     
  11. daiquiri
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    daiquiri Engineering and Design

    That is correct, and would be very desireable.
    But I understand that that the hull is an existing one, and all that can be done is to divide it in two halves and add another piece in between. But perhaps I have understood it wrongly.
    Loweland, could you please explain a bit more in detail the current state of the boat?
     
  12. LowelandSystem
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    LowelandSystem Junior Member

    I am not sure about the dead Load, need to look at the design log book, but approx 150 kg or heavier. here is the boat which I have to rectify it.
     

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  13. daiquiri
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    daiquiri Engineering and Design

    It looks like the paddle wheel is currently placed under the hood between the seats.
    In that case, if you close the tunnel to create a monohull, where will you put the paddle wheel on the modified boat? The picture in your OP is not showing any paddles below the hull.
     
  14. LowelandSystem
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    LowelandSystem Junior Member

    Actually the first one was propeller based, and in the middle box there was two gears which revolved 13 rpm per second.
     

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  15. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    So - if you close the central tunnel, where will you put the paddle wheel?
     
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