Stand-Up Rowing Catamaran

Discussion in 'Boat Design' started by John Larkin, Nov 3, 2020.

  1. John Larkin
    Joined: Jun 2006
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    Location: Idaho, USA

    John Larkin Junior Member

    Hulls to be built of 4mm plywood stitch-and-glue. Crossbeams are 3 1/2" x 1 1/2" fir laminated and curved to a 1" crown. 3 fore-and-aft beams are 2 1/2" x 1 1/2" fir. Deck is 6 mm plywood curved to fit the crossbeam tops. Hulls would be lashed to the crossbeams so the boat can be carried and stored in pieces. Rowing posts stabilized by non-stretch lines down to deck. For fitness rowing, camping, maybe take a passenger and picnicking supplies, or throw out an anchor and fish or nap.

    The Italians have a boat like this called "pattino".
    Your observations are welcome--but be nice, I ain't a real boat designer.
    SUR.jpg
     
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  2. clmanges
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    clmanges Senior Member

    First impressions, all just wild guessing, but ...

    Seems like it would entail a lot of fussing to put it together, what with the rowing posts and their stabilizing lines. Fake up a simulation with a piece of wood and some string to see if one person could do it alone. If the posts drop into sockets that would be less of a problem. And I ask myself why the posts are mounted to the deck but the stabilizing lines aren't.

    Also, the hulls have pretty fine ends, and even at that length, it might be hard to keep it from pitching. I think the operator will have to shift their weight back and forth, and at some cadence it might get feedback. Easy fix: make the hulls a little more full on the ends.

    Also, I wonder if the rowing posts shouldn't be moved off the lengthwise center, so the operator's weight will be there instead. Think about how luggage and/or passengers will affect trim.

    The experts will be along soon.
     
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  3. Blueknarr
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    Blueknarr Senior Member

    As a rower
    You will need much longer oars.
    At the drawn length it will be impossible to lift the blades out of the water for the return stroke
     
  4. BlueBell
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    BlueBell Ahhhhh...

    I love it.

    You're going to need some long oars.
    12' sweep oars from a rowing shell might do the trick.
    Cleaver blades could be an asset.

    I'd lose some rocker in the hulls along the keels.
    Turning won't be an issue with long oars.

    What's your waterline beam, less than 10"?
     
  5. John Larkin
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    John Larkin Junior Member

    Good observations. I'll think about addressing those in a V2. Thank you.
     
  6. John Larkin
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    John Larkin Junior Member

    I've drawn 10' oars...sounds like I need longer yet!
     
  7. Blueknarr
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    Blueknarr Senior Member


    Much longer
    Standing paddles are 6feet and the person is inches above the water.
    My rower oarlocks are two feet off of the water with ten foot oars
    Your oarlocks look to be at four or five feet above the water.
    I think you should lower the posts about a foot and lengthen the oars to eighteen feel.
     
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  8. alan craig
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    alan craig Senior Member

    It looks like a relaxing way to view the scenery. I've seen a Venetian sandolo being front-rowed on the Thames. Two suggestions from my armchair: you may be able to combine the rowing post tensioners with the cross beam fastening in some way for a neater faster set up. And how about a bipod and raked mast for when you might feel like a change of pace?
    It looks as if the crossbeams are permanently attached to the deck which means you have a 8ft x 8ft structure to transport.
     
  9. BlueBell
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    BlueBell Ahhhhh...

    Alan: See above quote from OP.

    EDIT: Oh, I see what you mean. Disregard.
     
  10. John Larkin
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    John Larkin Junior Member

    Good suggestions. Yes, that deck and crossbeam assembly is pretty big. I think they have to be all one assy to be strong, though?
     
  11. srimes
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    srimes Senior Member

    Good point. Can also help to make them fore-aft asymmetrical (ie, fatter sterns than bows).
     
  12. BlueBell
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    BlueBell Ahhhhh...

    I would suggest keeping them symmetrical fore-aft and vary the taper by waterline loading, weight shifting.
    Effective while maintaining a bidirectional capability.
    Simpler construction as well.
     
  13. John Larkin
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    John Larkin Junior Member

    yes, it would be great to keep it swappable end for end...how cool would it be to take off a beach already pointing the right way?
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    The fine ends, and the symmetry of them, was the thing that worried me a bit, I don't know what it would be like standing up trying to row something that was pitching madly, probably not terribly comfortable, I agree with what was said about fattening the ends a bit, and not be symmetrical, you won't increase resistance doing that.
     

  15. Blueknarr
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    Blueknarr Senior Member

    I love the idea of stand up rowing. You will be facing the direction of travel. Pushing instead of pulling on the oars.

    Some ergonomics to try to work into the design:
    The power stroke should be mid chest. With the return about six inches lower.
    A very athletic rower has a handle to oarlock and oarlock to blade ratio of 1:4. A casual rower might have a ratio of 1:3. And 1:2 for the truly wimpy.
     
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