pontoon / ferry design

Discussion in 'Stability' started by jklos2002, Feb 9, 2010.

  1. jklos2002
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    jklos2002 Junior Member

    I need to transport a compact track loader (skid steer w/ tracks) weighing 7800lbs to an island in a small inland lake. I have two heavy duty 18' long rectangular pontoons (22" x 32"), having total max. displacement of approx. 11000 lbs.

    I'm thinking of connecting the pontoons with either an aluminum deck supported by aluminum i-beams or a plywood stressed skin panel (2x8's 12" o.c. with top & bottom 3/4 plywood). It appears the wood box version would be much less $.

    The track loader is about 5.5' wide. Track length in ground contact is about 55"

    Any recommendations regarding minimum width of boat?

    Any recommendations on sizing aluminum i-beams & spacing?

    As needed, i also have 2 smaller (22" diam) 16' long pontoons that I could also attach, to contribute maybe 1500 lbs or so of bouancy.

    Thanks for any assistance you can provide.
    John
     

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  2. Squidly-Diddly
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    Squidly-Diddly Senior Member

    How do you plan on loading/unloading?

    If "landing" will the pontoon's structure support the 7800lb tracker all on one end as that thing crawls off?

    Do you have a ramp in mind?

    How long is the voyage?

    11K VS 8K doesn't sound like much margin of error if the 11K is 'displacement' as in totally submerged.

    Maybe some 'helper' flotation to hedge your bets?
     
  3. jklos2002
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    jklos2002 Junior Member

    I haven't given much thought to the ramp. I'm thinking of buying a pair of 12 foot loading ramps.

    The voyage is 1500 feet along shore & channels. no real open water.

    I'll probably use the pair of smaller pontoons for helper flotation.
     
  4. rasorinc
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    rasorinc Senior Member

    Using the 2 long pontoons have a welder create a bracket on each one to hold your 2 x 8s @ 12" OC and bolt thru them to the brackets and they become your cross ties. Only make the platform 2' wider then the loader and 3' longer and center the platform so that the ramp does not fall at the very end of the pontoons. The 3/4 plywood nailed at 6" OC will give you your sheer. Put one short pontoon in the middle if you need it and you could lash that one and put an outboard bracket at the rear of it. Yahama makes Hi Trust engines and a 9.5 hp will push your load. Or you could tow it and spend no money on an engine and use long poles at the shoreline.
     
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  5. jklos2002
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    jklos2002 Junior Member

    Not sure i'm following re. brackets. I've attached a sketch of what I think you're recommending.
    Thanks for your help!
     

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  6. hoytedow
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    hoytedow Wood Butcher

    Make sure the landing side of the pontoons is grounded and both it and the ramp are well secured before disembarking the machine or it might take a bath. I'm speaking as an interested amateur.
     
  7. rasorinc
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    rasorinc Senior Member

    Yes the bracket you drew is very adaquate. If you put a 2 x 8 rim joist on each side and use 3- 3/8 lag bolts per joist you would only need 2 brackets per side to bolt the leading and aft joist to the pontoons. I'm assuming you will go slow and weather will be good--also when your done you can take it all apart in a couple of hours. Use screws on the Plywood.
     
  8. Village_Idiot
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    Village_Idiot Senior Member

    Use a separate pushboat to push the pontoon barge - design the pontoon barge so you can easily push it from either end. If you put an outboard on it, you will have a whole slew of new regulations to contend with.

    When you get the thing built, paint some centering marks on the cargo platform. It will be critical that you get the load properly centered.
     
  9. jklos2002
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    jklos2002 Junior Member

    I was thinking of a 10hp or less outboard. What other regulations would need to be considered?

    Thanks for your help!
     
  10. jklos2002
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    jklos2002 Junior Member

    ramp location

    Rasorinc - Why do you suggest keeping the ramps away from the pontoon ends? I was thinking of something similar to attached photo.
     

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  11. jklos2002
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    jklos2002 Junior Member

    pontoon barge stability

    I'm seeking advice on reasonable minimum separation between two pontoons for a work barge.

    I need to float a bobcat compact track loader across an inland lake to an island. 2500 feet distance, no open water.

    Two main pontoons are 18' long, 22 inchs wide, 32 inch tall. Submerged displacement is approx. 11,000 lbs. Two round 22" helper pontoons will have 3,000 submerged displacement.

    The support deck will be 8-10 inches thick.

    Loader weighs 7,600 lbs. track width is 5.5 feet. Track contact is 55"

    Would a 9 foot wide boat be too narrow for stability?

    I found a similar design on the web hauling a tractor (photo below).

    Any help is appreciated!
     

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  12. Steve32
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    Steve32 Junior Member

  13. formsys
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    formsys formsys

    Another key piece of information - what is the vertical center of gravity of the load. Thats vital.
     
  14. Village_Idiot
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    Village_Idiot Senior Member

    Check your state's boating regs. Most states are pretty lenient about non-powered watercraft, but get pretty serious when you add power, no matter how small the powerplant (might need registration, taxes, maybe subject to CG regs (water safety stuff), etc.).

    I think you would be better off with a flat-front plate jon boat, maybe 18-foot with a 60hp Bigfoot outboard. You should be able to get a decent price on a used one - check gov't. auctions as they often use custom heavy aluminum plate boats for their work (yep, even small inland waters). If you don't use the boat when you are done with it, you can always sell it.
     

  15. daiquiri
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    daiquiri Engineering and Design

    It looks to me like your buoyancy and stability margin will be pretty tight.
    You'll need to consider the additional weight of the deck structure, steering and propulsion plant, personnel on board (1, I guess?), and some smaller equipment.
    You should give us the dimensions of the loader and (possibly) the position of it's center of gravity. What is the weight of your pontoons? How many persons on board during navigation and loading/unloading? What kind of propulsion you plan to use?

    Also, take a look at this project - to get you an idea about things you'll need to consider: http://www.boatdesign.net/forums/boat-design/putting-log-loader-barge-28481.html

    P.S.
    What model is that red car behind the pontoons?
     
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