Is there an existing hull shape that fits this bill?

Discussion in 'Boat Design' started by CatBuilder, Mar 21, 2012.

  1. CatBuilder

    CatBuilder Previous Member

    I'm wondering if there is a hull shape out there that has the following:

    *Less than 16 feet long
    *Very narrow and efficient when lightly loaded - low wetted surface area, easily driven
    *Ability to carry 1500lbs or so when fully loaded, but at reduced efficiency
    *4' beam max

    Is there such a hull out there that exists today?
    Any plans or sets of lines for one like that?
  2. bntii
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    bntii Senior Member

    1 person likes this.
  3. XJ9
    Joined: Mar 2012
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    XJ9 Junior Member

    OK, this one doesn't quite fit your length and beam criteria by a couple of inches, but I don't see why it couldn't be "squeezed" slightly to fit. John Welsford has always been happy to answer questions about his designs and well worth an email to him if you are serious:
  4. jehardiman
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    jehardiman Senior Member

    Yep, CatBuilder just spelled out the original TLR. Though they tended to be longer for speed.
  5. thudpucker
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    thudpucker Senior Member

    Here's a Jon that fit's your needs pretty well. This is a plan boat and I modified the picture with MS Paint.
    It's amazing what a Jon can hold and still only draw a few inches of water.
    Beaches easily, stable, and rows easy.:)
    joh big mama (438 x 235).jpg Jon empty.jpg
  6. waikikin
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    waikikin Senior Member

    Is this a tender for your cat? 4' is pretty narrow for 16', whats the propulsion? Jeff.
  7. CatBuilder

    CatBuilder Previous Member

    I'm sorry, I should have been much more specific about efficiency. I'm looking for efficiency like this:


    However, I want to make it more like the vaka of a trimaran, so it has no wetted surface area when carrying 500 lbs, but lots of displacement as you pass 500 lbs and can actually carry a 1500 lbs load.

    I'm probably going to have to design this one myself, huh?
  8. CatBuilder

    CatBuilder Previous Member

    Sort of a combination between the power proa in my last post and thud's Jon boat post....
  9. nimblemotors
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    nimblemotors Senior Member

    This is the kind of power tri I am considering building, long and skinny.
    The proa setup solves the docking issue, as long as you can come alongside from the appropriate direction.

    The tri could be designed to have the amas in the back and a big flat upper deck that connections them,
    which is the cargo load area. I'm thinking if the amas are big V shape, they will take the weight when
    loaded down, but otherwise tread lightly when just one or two people aboard.

    I suspect you're thinking as I am that it will be a tender for the big cat.
    Mostly one or two people going ashore, but sometimes more and sometimes lots of supplies to shuttle.

  10. rasorinc
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    rasorinc Senior Member

  11. CatBuilder

    CatBuilder Previous Member

    Exactly, nimble. We are after the exact same boat for the same purpose. I have 16 feet of space to hang one between my hulls.

  12. messabout
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    messabout Senior Member

    The Jon boat is practical, easy to build, burdensome, and spacious. It violates your SOR in that it has excessive wetted surface and it is not a particularly good rowing boat.. The Proa thingy appears to violate the max width specification, when heavily loaded it will also have lots of wet surface and it would be a bear to haul up on the deck of a mother ship. It's pretty jazzy looking though.

    The Whitehall or perhaps some variation of a Seabright skiff would do the trick especially if you could allow it a little more length. Maybe even an Adirondack Guide boat.
  13. CatBuilder

    CatBuilder Previous Member


    Thanks. I will look some of these boats up you suggest.

    Yes, the Jon boat does violate the SOR in that it has way too much wetted surface area, so not very efficient.

    The proa, however, is much closer. It does not violate the beam requirement, since the amma is demountable. I guess I could mention that something that is demountable would fit that beam requirement.

    The other thing about the proa that's within spec is hauling it up. I will most certainly have davits hanging between the 16ft of space I have between my hull aft of the aft beam. This means I can haul any 16ft or less boat (without a lot of beam) up by cranking a winch. The proa, BTW, weighs 80lbs, so you probably could haul it up even without using the winches - just by hand pulling on the lifting lines.

    Large wetted surface area when fully loaded is OK with me. I would hope to have minimal wetted surface when at 500lbs or under.

    Will keep on looking.

    I was just curious if something like this already existed before I went and designed one. I wanted to save some time.
  14. CatBuilder

    CatBuilder Previous Member

    Rasor, that thing is kind of cool too. Will take it under consideration.

    It seems a fusion of several types of boats is really what I'm after.

  15. nimblemotors
    Joined: Jun 2009
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    nimblemotors Senior Member

    I'd really like mine to be amphibious, as was thinking something like snowmobile belt drive and some wheels in the amas and the main hull.
    Probably wanting too much I suppose.

    In the USA, they'd never go for the "car" part, but in Mexico I saw all kinds of things driven on the road! And one doesn't need to actually drive on roads, but just be able to drive it out and and can load it in dry conditions.
    park it somewhere where they don't charge you dock fees or ramp fees
    The yellow one looks like it would get you wet pretty easily.

    I'm thinking I need to build this boat first before the big cat, can throw away a couple prototypes and get some build experience.
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