Design challenge: truck capable barge from Lowe's

Discussion in 'Boat Design' started by DogCavalry, May 3, 2020.

  1. DogCavalry
    Joined: Sep 2019
    Posts: 749
    Likes: 335, Points: 63
    Location: Vancouver bc

    DogCavalry Senior Member

    New member Randall Brower posed a fascinating question: is it possible to make an acceptable vessel to meet his SOR?

    SOR: Materials strictly from Lowe's.
    Must be capable of transporting a laden pickup truck on a moving river.
    Must be durable enough to survive a few years in Alaska.
    Must be cheap enough to be better than the current alternatives.

    I'm already foaming over at the brain pan with ideas.
    DC
     
    BlueBell and bajansailor like this.
  2. bajansailor
    Joined: Oct 2007
    Posts: 1,314
    Likes: 381, Points: 83, Legacy Rep: 37
    Location: Barbados

    bajansailor Marine Surveyor

    Thanks for posting this DC.
    Let's see what the collective wisdom on here can come up with.

    Here is a link to Randall's thread.
    Advice on Raft/barge/ferry from lumberyard material for occasional 6 mile trip https://www.boatdesign.net/threads/advice-on-raft-barge-ferry-from-lumberyard-material-for-occasional-6-mile-trip.63782/

    And copied below are his two opening paragraphs :
    ----------------------------------------
    I live on the Yukon River in Alaska and the residents of my village often need to move large heavy objects 6 miles up the Yukon to the road and back again. A $100k landing craft would be great but overkill for the few times it would be used each year. The river is only navigable 5 months of the year, frozen otherwise. Natives have been lashing a dozen 30-40ft logs together for years but I'm looking for something more durable. Whatever the design is, it must be recovered in September and launched in May. Anything left in the water or on the bank over the winter will be destroyed by ice breakup in the Spring. Log rafts are too flimsy for launch and recovery.
    I'm limited to lumberyard material than can be bolted together and have enough strength and stability to transport a 5000 lb vehicle or similar load in the occasional 2-3 ft waves. Hydrodynamics are unimportant, just stability. Propulsion would be large outboard or pushed by a Jon boat. My thought was log raft-like dimensions (~20'x40') made from whatever Lowes sells. I just have no idea what actual size is required or whether 2x12 lumber, 4x6 timbers or plywood would handle the stresses and buoyancy requirements. We have a bulldozer for launch and recovery.
    ---------------------------------------------------------

    Randall later mentions that the vehicle could be an 18' x 8' Chevy Suburban truck.
    And that for a Rolling Barge kit, "$3,500 plus the cost of the wo0den deck gets me a 10' x 20' barge with 9200 lbs of payload. I've got to drive 12 hours one way to pick them up but I think that's the right solution. "
    https://rollingbarge.com/floating-dock-kits/
    My concern here is that while 20' x 10' might have enough buoyancy in theory, I would have doubts about the stability - maybe a barge 20' x 20' as a minimum?

    Re the requirement for materials from Lowes, they sell 50 gallon plastic barrels for collecting rainwater, but second hand barrels that had supplied consumable (by people) liquids would probably be cheaper (?)
    https://www.lowes.com/pd/FCMP-Outdo...ed-Plastic-Rain-Barrel-with-Spigot/1001844096
     
    DogCavalry likes this.
  3. fallguy
    Joined: Dec 2016
    Posts: 3,549
    Likes: 501, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    I hate to be the bubble buster, but if you want to build a barge and spend money on it; then steel pulled each winter by a tractor wins.

    Otherwise, the felled tree wins it for me.
     
  4. philSweet
    Joined: May 2008
    Posts: 2,351
    Likes: 210, Points: 63, Legacy Rep: 1082
    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    There seems to be some overkill that needs killed off in the op's mind. Birchbark canoes routinely handled 5000 pound loads of buffalo skins and 6 crew. I'm pretty sure I could make a barge out of a blue plastic tarp or a roll of tarpaper, some found objects, and a pocketful of nails that could move a Suburban up the Yukon once.

    A barge wide enough to drive into and open the door enough to squeeze out has plenty of stability.

    It will draft about 10" at 10750 pounds.
    So B is about -5 inches.
    cg for the stock '98 Suburban is listed as 0.752 meters. Let's allow for a lift kit and cargo and call it 7000 pounds at 1 meter. Boat has the remaining mass, 3750 pounds, at a cg of about 0.0. Vessel cg is thus about two feet. (Sorry for the mixed units, the data on the Suburban was in metric, and I converted piecemeal back to English as I went along).


    If you want a GM of 2 meters,
    BM = GM + BG = 6.5 + 2 (feet) . (I'm assuming the wheels are about 5" below WL, same as B.)
    BM = 8.5 feet
    I = BM*V = 8.5*172 = 1462 ft^4
    beam = (1462*12/24)^0.333 = 9.0 feet.
    A 2 m GM is probably a good idea with a live vehicle suspension. Putting four blocks under the frame and ratchet strapping the thing down on the blocks would be smart.

    16 sheets of 3/4 structural ply, 5 gallons of roofing tar, locally sawn flitches or a bundle of 2x6 pt (got a chainsaw mill there?), and about 50 pounds of coated deck screws ought to about get it. I can still find forgotten/mismixed paint for $5/gal, but you probably can't in Alaska. Figure 20 gallons of paint. Paint everything.

    This is all just from general rules of thumb. I haven't designed anything here.

    <Edit> A bundle of 2x6 is more than you need. 1oo should do it.
     
    Last edited: May 3, 2020
    DogCavalry likes this.
  5. Barry
    Joined: Mar 2002
    Posts: 1,336
    Likes: 168, Points: 63, Legacy Rep: 158

    Barry Senior Member

    Cut up several pieces of lumber 2 x 12 x 24 feet, I am sure that there a quite a few Alaskan Mills up there, Fir would be prefered but spruce or pine will work. you would not have to plane the dimensions but maybe on the 2 inch edge

    Using a 1 foot spacing for the stringers form up a grid 24 feet long by 12 feet wide. Install several cross braces from the same material. Cover with 3/4 inch sheets of plywood. Glue the joints, DogCavalry likes PL. I would use an epoxy.
    Use stainless screws. At the front, you would want to turn up the bottom a bit and you could do this in say the first 4 feet. Using 3/8 inch ply to make a bend, then laminate another layer of 3/8 on to the first to make 3/4 of an inch.
    Paint everything that you can. This displaced volume would theoretically carry 12 x 24 x 1 foot deep x 62 = 18,000 pounds less the weight of the wood and give you a reasonable factor of safety for engine, fuel, and load.
    Quite a TV series you had up there
     
    Last edited: May 4, 2020
    DogCavalry likes this.
  6. DogCavalry
    Joined: Sep 2019
    Posts: 749
    Likes: 335, Points: 63
    Location: Vancouver bc

    DogCavalry Senior Member

    My concern with some of the simpler ideas is that the truss is too shallow. A laden pickup will have more than half of its weight on the rear axle. That's a moving load that has a contact point of only 1 square foot per tire. So the extent of hull necessary to give adequate roll stability places the buoyancy well out from the point of load. Considering transverse framing, each frame must be able to support most of the weight of the truck, in its turn. Considered, as I do, as a simply supported bridge, that's a heavily loaded truss.

    Bluebell related in the OP thread, that a 42 by 14 water truck was marginal with a loaded pickup truck on board.
     
    Last edited: May 4, 2020
  7. Barry
    Joined: Mar 2002
    Posts: 1,336
    Likes: 168, Points: 63, Legacy Rep: 158

    Barry Senior Member

    It is not really a simply supported bridge as the hull is supported relatively uniformly by the hydrostatic pressure under the hull. As compared to say an end supported beam, truss, bridge
     
    DogCavalry likes this.
  8. DogCavalry
    Joined: Sep 2019
    Posts: 749
    Likes: 335, Points: 63
    Location: Vancouver bc

    DogCavalry Senior Member

    You're talking my language, Barry. It is indeed a more complex system than that. I image buoyancy moving laterally in a slight roll condition, but the buoyancy in the middle and edges loads the truss more.
    A deep cat where the hulls were largely under the wheels would be a simpler load
     
  9. DogCavalry
    Joined: Sep 2019
    Posts: 749
    Likes: 335, Points: 63
    Location: Vancouver bc

    DogCavalry Senior Member

    Can't buy that at Lowe's. Although steel is cheap.
     
  10. BlueBell
    Joined: May 2017
    Posts: 1,331
    Likes: 269, Points: 83
    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    Not by the time you pay for shipping. That's a big part of this situation.
     
    DogCavalry likes this.
  11. DogCavalry
    Joined: Sep 2019
    Posts: 749
    Likes: 335, Points: 63
    Location: Vancouver bc

    DogCavalry Senior Member

    14' by 27' catamaran. Cat makes truss design much simpler because half load on each hull.

    I like the idea of green lumber framing, maybe strip planked, also with green lumber. PL is fine with wet wood. Although I'd cut my strips and let them bake in the sun for a bit.
     
  12. BlueBell
    Joined: May 2017
    Posts: 1,331
    Likes: 269, Points: 83
    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    An aft slip for the pushboat would be an asset but forward visibility would be seriously hampered by cargo.
    A side-tow would work downstream but upstream... stern tow I guess.

    EDIT: Cancel that, he's willing to go "large outboard"! Self propelled.
     
    DogCavalry likes this.
  13. BlueBell
    Joined: May 2017
    Posts: 1,331
    Likes: 269, Points: 83
    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    OP also mentioned 2' - 3' seas but then said heavy transport days would be limited to calmer conditions.
    How fast does this river flow?
     
  14. Squidly-Diddly
    Joined: Sep 2007
    Posts: 1,678
    Likes: 108, Points: 63, Legacy Rep: 304
    Location: SF bay

    Squidly-Diddly Senior Member

    see my gallery for modular barge concept. one of the features is that you could tow the dismantled boat with the same heavy-duty pickup or van that it could also carry on water. use cross members for ramps. idea is it would be "amphibious" in that it could travel on water or land without leaving pieces behind, but without compromises of a true one-piece amphib, and with a different sort of added complexity.

    didn't consider making it out Lowe's material.
     
    DogCavalry likes this.

  15. DogCavalry
    Joined: Sep 2019
    Posts: 749
    Likes: 335, Points: 63
    Location: Vancouver bc

    DogCavalry Senior Member

    I'll have a look, Squidly-Diddly.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.