Catamaran like Rowboat for lake fishing

Discussion in 'Boat Design' started by timnphx, Jun 14, 2013.

  1. timnphx
    Joined: Jul 2008
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    timnphx WishIwasWorkingWwood

    I am thinking of building another rowboat for lake fishing here in AZ. I have built a strip-ceder canoe in the past and also built a lapstrake rowboat/sailboat but I am wanting a small boat that can be real stable for standing in while fly casting. The typical bass boat gave me the idea of something stable to stand in but I cannot be trusted with my footing to not fall off the flat and open deck style of the bass boats. So I started thinking about how I made my canoe and other rowboat, and came up with something like a twin-haul or catamaran like design that will have a small middle deck that is wide enough and stable to stand in on small waters such as lakes here in AZ. Anyone have any suggestions on how to insure the design details are sound? Or maybe there is already an off-the-shelf plan out there?

    Last edited: Jun 14, 2013
  2. thudpucker
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    thudpucker Senior Member

    A Jon boat would probably work just as well.
  3. messabout
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    messabout Senior Member

    A real smart boat guy declared: "The primary use is primary". If your main need is to perch on a tall seat or stand up while fly casting then what you have drawn might work for you. You feet will be well above the water level because of the mid deck elevation. Not the most stable design idea but if the boat is wide enough it will tolerate some human movement.

    The boat as drawn,will be clumsy to maneuver, it will have a lot of windage, it will not be easy to propel, it will need a lot of work and material especially if you strip build it. If you are thinking small like ten feet or so then check your displacement calculations carefully when designing the cat hulls. You may not be satisfied with the result if the boat is to be small. If you make it wide enough, and the floats fat enough to do what you want, then it is even more unwieldy.

    Perhaps a wide flat bottomed boat would serve your purpose as well or better. It would certainly be easier and less expensive to build, It would be lighter, probably easier to propel, could have less windage, and it could give you sufficient stability to fly cast with reasonable safety.

    Let's see what others have to say.
  4. upchurchmr
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    upchurchmr Senior Member

    Here is an example of strip planked hulls.


    Probably needs to be bigger if you want to walk to the edge.
    This row boat is for my light weight wife, each hull is 6" wide, 11' long and it is 5' wide overall. Sized to fit in the back of my pickup (fullsize). Rows very easy.

    Strip planking is quite easy, but takes a little practice. The tooling for making these hulls is extremely simple, you use the same tool twice. The cross beams are hollow wood (2# each).

    The picture you drew will be complex and difficult to build. Simplified lines, straight beams, a flat deck will get you something buildable in a reasonable time.
  5. philSweet
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    philSweet Senior Member

    I'd put the minimum practical size of that at around 13x7. I'd just use simple hard chine flat bottom stitch and glue build out of 6 or 7 mm marine fir ply with a skin of glass weave. Flat panels have considerably better damping compared to the round bilge hulls you drew. As Messabout said, you will be perched on top and there will be a sensation of the boat wanting to scoot out from under you. That is less apparent in a boat like a Carolina Skiff where you are in the boat. And there won't be any weight savings vs a mono like the above sort of skiff when compared on an equal stability basis. You need to have 400 pounds of hull under you if you don't want that skatey feeling.


    There're always belly boats:D

    they succeed because you are lower in the boat. That is the biggest problem with the cat. You have to ovecome the increase in the center of gravity, and if the boat is very small and light, you can't.
  6. PAR
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    PAR Yacht Designer/Builder

    I think a proa or outrigger canoe, might be a better way to go. You can hoist the ama(s) and row with little resistance, good maneuverability and little drag. When you're ready to fish, drop the ama(s) in, to gain a huge stability improvement and have at it.
  7. latestarter
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    latestarter Senior Member

  8. upchurchmr
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    upchurchmr Senior Member

    The catamaran can be extremely manuverable or better tracking with a choice of how far the stem and stern are immersed in the water.

    Placing them at the waterline caused my original boat to be extremely easy to turn (but almost impossible to track). A modification to drop the stem and stern 1.5 inches resulted in an easy tracking boat, with "reasonable" turning - of course reasonable depends upon your definition - I was looking for tracking.

    You won't like lifting a proa ama unless the main hull has significant stability already, and it will be difficult balancing it out while paddling.
    You wouldn't believe how easy paddling the one I showed is unless you try it.
  9. portacruise
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    portacruise Senior Member

  10. messabout
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    messabout Senior Member

    Upchurch; I am fascinated with your rowing cat and its sliding seat that appears not to slide. That was done to minimize pitching I would guess.

    How long does it take to get used to the different setup where the oar locks move rather than the seat?............ Hmmm, am I seeing this correctly?
  11. upchurchmr
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    upchurchmr Senior Member


    You got it first time out.

    This is an old idea, copied from others.
    An 11' boat (to fit in the bed of a truck) does not have enough length to keep from pitching excessively if you use a sliding seat like all the competition sculls.
    In fact this boat is very fine fore and aft (symmetrical) and will put up with almost no pitching movement.
    The sliding feet rig keeps the body fixed, and the feet, oarlocks, and oars move.
    This means for my ~124# wife, something like 100# stays fixed, with probably 35# moving.

    The only difference is that your legs pull the oars, etc., to you, moving only 35#. A sliding seat will cause the legs (pushing) to move the whole body of 125# to move, requiring more force. However the sliding seats typically have the track running "downhill" so it is only when you are really going all out that you move 125#. So pulling in with your legs is the primary difference.

    The other thing is that the force of the oars is transmitted directly to the hulls in a sliding seat. In the sliding feet or sliding rigger the force is transmitted thru the seat of your pants. We use a Sorbothane pad to help, it has lots of friction/ stickiness. In practice at our best stroke/ force, we do not recognize anything happening at the behind interface. You just sit there.

    I personally believe the motion is exactly the same, just a little less force required. You would probably be converted within about 20 strokes. It is much more difficult to learn the coordination for a good stroke than changing from a sliding seat.

    The only thing I would like is to make the boxy aluminum wheel housing in some other manner, I think the looks stink. The ends of the crossbeams have been closed in and the rigger has been rebuilt to look better.

    This is actually a very simple boat, the hulls and crossbeams are easy to make. The hulls are just an arc of a circle looking from the top (each side) and the hull rocker is an arc of a circle flattened out a little at the stem and stern.

    Oh by the way, my wife out runs me easily since her hulls are 6" wide to my 12" wide (almost double the weight to carry).

  12. liki
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    liki Senior Member

  13. bajansailor
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    bajansailor Marine Surveyor

    Upchurch, I am just wondering if you got the idea from the Rocat?

    It seems to be a very complicated and hence expensive boat, which is perhaps why it does not seem to have 'taken off' - yours looks much simpler.
  14. upchurchmr
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    upchurchmr Senior Member

    Actually I saw this after my concept was in work.
    I agree it seems un-necessarily complex in the mechanism. I couldn't quite see the point.
    A couple of good things on the overall boat:
    The rocat will obviously take bigger sea
    Has some protection for the rower.
    Things I don't like:
    Will have to be transported on a trailer
    Would have to be carried by 2 people - if it is possible
    Heavier than mine in spite of primarily being carbon fiber. Note they only give you the weight of each hull, not the crossbeams, seating area, and mechanism.
    Flat immersed transoms - more drag at any conceivable speed.
    Things I like about mine:
    Short length
    Lighter weight - 50# (not well optomized - could be lighter - primarily cedar and glass covered)
    Simplicity means I could make it as a one-off in my garage with limited tools.
    I can carry it by standing in the middle just behind the front beam and pick it up on the Rigger slider tubes. Easy to balance and control, I.E., one person transport.
    Double ended symmetric hull - less drag. You will not see virtually any wake as fast as I can row (I don't last very long at my fast pace). My wifes boat also has no inteference wave drag between the hulls - not true of mine.

    There was a boat I took the 3 wheels per side idea from, my original had 4 per side which was unnecessary. Sorry I cannot remember the name right now.

    One last benefit - much cheaper. Probably $300.

    Especially cheaper that what I just saw on their web site - "It is not currently possible to buy a Rocat"

  15. Squidly-Diddly
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    Squidly-Diddly Senior Member

    "Wavewalk" cat-kayak might not be bad starting point.

    Notice he says front and back are interchangable, and inside hull appears to be big flat surface. Might be fairly easy to do in wood, maybe Stitch and Glue.

    Seems like the general layout cries out for 4 watertight compartments at the four corners, which his design doesn't have.
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