Barge to carry a single pick-up truck

Discussion in 'Stability' started by DogCavalry, Sep 9, 2023.

  1. bajansailor
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    bajansailor Marine Surveyor

    For a first entry in the design spiral, if we assume a rough block coefficient of say 0.6, then the displacement at 1 metre draft would be :
    Displt = L x B x T x Block coefficient x 1.025 (where T is draft, and 1.025 is the density for salt water in tonnes)
    = 14 x 5 x 1 x 0.6 x 1.025
    = 43 tonnes.

    So this gives you 23 tonnes for the boat itself.
    You would now have to do a rough weight estimate to see if this will cover everything that the boat will need re construction and outfit.
     
  2. DogCavalry
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    DogCavalry Senior Member

    Hmm. I think those dimensions are a bit small.
     
  3. BlueBell
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    BlueBell . . . _ _ _ . . . _ _ _

    That's kinda low for a barge isn't it?
    Or are you thinking sea sled hull.

    Which dimensions in particular?
    All of them?
     
  4. DogCavalry
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    DogCavalry Senior Member

    I had made the calculation for material take-off with the wrong specific gravity for douglas fir, giving an excessively high estimate for lightship displacement. Although the box should be 4' deep, not 3' deep. Gives insufficient freeboard at full load for comfort. So 46*16*4'. Martin was guessing for a sea sled form. It's a conservative number but that's fine.
     
  5. Rumars
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    Rumars Senior Member

    I have to ask, what's the reason behind the 20t limit? Why not 30t so you can embark a fully loaded 20ft container and a self powered dolly?
     
  6. DogCavalry
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    DogCavalry Senior Member

    Good question. The number came from a conversation with the GC (General Contractor) we work with, who manages admin and materials from his office in the city. I was working on a small barge for managing project support, to fill in the gaps around the commercial barge logistics, but he pointed out that if we are going to do this we might as well plan to do all our own logistics. In which case a 40,000#, or 18,000kg load is more representative of a large material delivery. A complete house would be roughly 160,000#. Roughly. Built over a year. So a commercial barge to handle the 70 ton foundation pour. Then:
    1-Our barge for framing and sheathing plywood.
    2-Roofing, siding, windows and doors
    3-Drywall and insulation
    4-flooring and cabinetry

    We aren't likely to need a fully loaded sea-can.

    And as much as any other reason, I have to draw a line somewhere. At 35' and 6 tons I was confident. At 60' and 30 tons I'm absolutely out of my depth. Tomorrow is my 59th birthday, and so I no longer have the confidence of youth.
     
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  7. Blueknarr
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    Blueknarr Senior Member

    But you do have the wisdom of age
     
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  8. DogCavalry
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    DogCavalry Senior Member

    Indeed. Includes knowing my own limitations.
     
  9. DogCavalry
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    DogCavalry Senior Member

    Well, here's a first bash. Structure entirely built from 2*4 boards, because for a carpenter doing residential construction in Canada they are as cheap and common as dirt. Those are 8.9 cm by 3.8cm. To handle high moving loads requires a thick deck. So 2*4 stood on edge and face bonded. Then a grid of transverse bulkheads spaced on 2'/61cm centers made of 2*4's flat laid, so each bh is 3.5" thick, with 21.5"/55cm clear spans between. Longitudinal bulkheads at center, 3.5' out from CL to correspond with ramp attachment hinges, because of course ramps must match wheelbase of typing vehicles, at bottom chines, or keels, and forming topsides. Hull bottom planked with 2*4's, so planked 1½" or 3.8cm thick. Inside liberally coated with epoxy, but not glassed. Outside all glassed with 56oz of biax.

    Allowing a half ton for hardware that comes to 30000#, or 13700kg. Material cost to me is $36000 monopoly money, or around $25000 us or Euros. Unknown extra cost for ramps, ramp hinges and deck hardware. And of course lost billable hours.
     
  10. DogCavalry
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    DogCavalry Senior Member

    Like this. I left out a pair of longitudinals at the chines. IMG_20240309_123917665.jpg
     
  11. Barry
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    Barry Senior Member

    https://www.boatdealers.ca/boats-fo...e-work-platform-fort-langley-british-columbia

    $55k Canadian bucks, 90,000 pound capacity, hiab, genset, Made out of aluminum
    No lost billable hours, does it get any better than this?
    Certainly some modifications required, ie a ramp, but you have to build a ramp anyway for what ever you build
    Looks like a DC project to me


    I would take the time to visit a bunch of commercial marinas down your way, looking for unused barges, landing craft that may have outlived 24/7 activity or too small for
    commercial profitable ventures.
     
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  12. DogCavalry
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    DogCavalry Senior Member

    They sure don't tell you much. Could my little Serenity push that?
     
  13. BlueBell
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    BlueBell . . . _ _ _ . . . _ _ _

    It's in Langley!
    Go have a look.
    Take good pictures.

    That's a great buy if it's in good condition.
    Look for signs of electrolysis.

    "SLUSH", I love it!
    Looks like it was a fish packer.
     
  14. Barry
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    Barry Senior Member

    Unknown, certainly not at 15 knots but you could also put a 200 hp motor on the back, with simple steering and have Serenity tow. The combination should get you a better speed.
    Of course you would need a second driver but it sounds like you have crew.
     

  15. Rumars
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    Rumars Senior Member

    Ok, 18t as a typical load, how do you plan to mange loading/unloading and on site storage?
    You should talk with your chosen NA about draft and center of gravity for the load. If you distribute the load wide and flat you can get away with a shorter and wider boat, maybe even a catamaran. With 20t planing is only an option if you install ~2000hp, a catamaran let's you push close or even over displacement speed with lower power.
     
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