need help with a design

Discussion in 'Boat Design' started by snoman774, May 14, 2008.

  1. snoman774
    Joined: May 2008
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    Location: arkansas

    snoman774 Junior Member

    hey guys im new here and got a few questions.
    i want to build a for lack of better description a barge. about 8x24 maybe
    here is what my requirements would be
    trailerable meaning width trailer and all less than 8ft 6in
    carry about 10 people on a medium sized river usaully pretty slow
    flat deck for fishing
    small center console
    prferably be able to use my 1988 johnson 25hp
    shallowest draft as possible
    extremely stable 6 of the 10 on board fishing will be children
    i first considered using 55 gal drums for pontoons and coating them with spray in bed liner but thats gonna be expensive so now im thinkin plywood stitch and glue with 2x2 or 2x4 for frame doesnt need to be pretty just support the weight go in shallow water get back up river to boat ramp and affordable.
    please any ideas on some plans or maybe some one on one help
    i can handle myself around the shop but not an expert woodworker and never thought about building a boat till just a few weeks ago
    thanks
    chris
     
  2. dragonjbynight
    Joined: Apr 2008
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    Location: Indiana

    dragonjbynight Senior Member

    Welcome!
    From the sounds of it, your looking for the versatility of a pontoon right? I would wonder if you might not be better off finding a "beat" pontoon boat, one that needs a bit of work. That would give you the platform to do as you please with. It would also be quite a bit cheaper, as it would take less wood and fiberglass/epoxy/paint/time.

    As far as building one from scratch, fraid i don't have the knowledge for that, but i know that there are plenty of others here that do, and most would be willing to offer you some good suggestions.
     
  3. snoman774
    Joined: May 2008
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    Location: arkansas

    snoman774 Junior Member

    yes versatility of a pontoon but i read somewhere about the stability of pontoons say if you overloaded one pontoon it might flip especially in a current and all i could think was somebody catching a large catfish say 30 to 40 pounds and all the kids run to one side to see.
     
  4. dragonjbynight
    Joined: Apr 2008
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    Location: Indiana

    dragonjbynight Senior Member

    Personally, i haven't heard of that, though, i am by no means a pro. I would imagine it could be possible if everyone is leaning over the side and broadside to the current.

    Problem with a wooden boat of that size would also be the draft, it is going to be heavy, and sit fairly low in the water, I don't know if it would be able to traverse the shallows as your looking for, not that width and length anyhow.
     
  5. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    A plywood barge wouldn't be heavy, it would be much more stable, probably have less draft then a pontoon of similar size and you'd be in the boat, rather then on it, which makes most feel much better.

    You'd have trouble pushing it at any real speed with a 25 HP outboard, likely restricted about 7 MPH (displacement speed) in either plywood box or pontoon configuration.

    Draft is more a function of how deep the lower leg of the engine, then the hull type used. You're going to have at least 15" of lower leg hanging below the hull, regardless of hull type used. The only option around this is a tunnel hull, Sea Sled hull, jet or surface drive. These give minimum draft, but like everything at a cost.

    It would be easier to build a plywood barge then welding up a set of pontoons.

    What is your budget, your skills and time frame for such a craft?
     
  6. CTMD
    Joined: Dec 2007
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    Location: Melbourne, Aus

    CTMD Naval Architect

    Talk to your local roto-moulding (water tank) company, many have standard catamaran pontoon mouldings. These are typically bow section, stern section (sometimes interchangable) and 2 foot long parallel mid body sections. You simply order the number of parallel sections required to get up to your desired length. It then becomes a case of building a strong platform and bolting the hulls on.
     
  7. snoman774
    Joined: May 2008
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    Location: arkansas

    snoman774 Junior Member

    budget = not enough to be building a boat maybe 1500 to 2000 plus a rebuilt motor
    time frame= hopefully by next summer
    skills= i feel confident i could build a recttangular box with a slope on the front and make it sturdy but i have never used fiberglass and resin and assume that would be the way to seal it up. hadnt thought about the lower leg on the engine being my limit on draft but its obvious so thats where my head is lol could i maybe build a simple flat barge and maybe a raised transom or would it matter? what about maybe making into tunnel hull??
    in arkansas u have to have liability ins for anything over 50 hp do you think a 50 would push say 8 by24 i think i could find a use one to buy and rebuild. really 7 or 8 mph would not be to awful bad. maybe change props for more tourqe going up river???

    more questions sure to come, lol
    chris
     
  8. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    A prop change on your 24'x8' whatever, will not matter much. It's the wetted surface and weight it has to shove. A 50 HP will get you up on plane and ruffle your hair a bit.

    You don't have to use epoxy and 'glass, you could just use paint and nails. They built shallow draft boats without it for many centuries, before it's invention, honest.

    This said, durability can be greatly increased with the use of epoxy and 'glass, particularly on the outer hull skin, but it's not completely necessary.

    A tunnel or Sea Sled hull would be a good way to go. A Sea Sled hull will use the limited available power the best (get the most speed).

    You'll be hard pressed on such a limited budget to produce a boat. Your best bet would be to find a worn out boat, suitable for your needs with a 500 dollar bill (or so) and toss a paint job and other items at it with the remaining budget.
     
  9. ted655
    Joined: May 2003
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    Location: Butte La Rose, LA.

    ted655 Senior Member

    The mention of kids & current makes the pontoon less desirable. Build the barge. 30" sides will keep em in.
    I show these pictures as an example of how easy it is to build a ply barge on a "2 rail" jig. Obviously mine is way bigger than your needs.
    Email me for more info IF this interests you at all, for help & answers to any questions.
    .
    Another, slightly more involved idea is a dory style, (Glen-Ls "Lucky Pierre"), or this is another place, OR a Snake River drift boat.
    http://www.boatdesigns.com/products.asp?dept=539
     

    Attached Files:

  10. snoman774
    Joined: May 2008
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    Location: arkansas

    snoman774 Junior Member

    would the joints have to be super tight or use something like a caulk?
    or does the paint take care of this


    if you havent noticed i have no clue about boatbuilding.
    thanks
    chris
     
  11. ted655
    Joined: May 2003
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    Location: Butte La Rose, LA.

    ted655 Senior Member

    I would take advantage of a "little" modern materials. I would apply glass tape along all the seams, bedded in epoxy, then coat the whole hull, (below the water line), with Coal Tar Epoxy I'd also use screws instead of nails & Titebond 2, (or better yet), 3 as adhesive.
     
  12. snoman774
    Joined: May 2008
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    Location: arkansas

    snoman774 Junior Member

    ok
    glass and epoxy for all the seams check
    screws check (any particular type)
    titebond check (home depot or lowes maybe)
    coal tar epoxy dont know anything about this at all

    looking at your pics thats what i had in mind i think (but that looks like full sheets of plywood on the sides WOW)
    what about braces for the sides is there a deck or are you standing on the top side of the hull???

    what kind of angle am i looking for on the bow??
    and what about the transom or motor mount what does it need to support the engine?
     
  13. snoman774
    Joined: May 2008
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    Location: arkansas

    snoman774 Junior Member

    ok so thats a bit much them lol
    ruffle my hair lolol
     
  14. ted655
    Joined: May 2003
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    Location: Butte La Rose, LA.

    ted655 Senior Member

    This is a big hull for a house on top. You are looking at the bottom of the hull. The deck will be added after we turn her over.
    Stainless screws are good, BUT, they are soft, hard to work with and unforgiving. 1 glitch & you are twisting the remainder out with vice grips. I HAVE to use them because my ply is pressure treated, (long story). I get along OK with them now, but there IS a learning/ cost curve. Plated steel is OK if using regular ply.
    Beauty, (bow angle) is a matter of what looks good. The longer the rake, the smoother the ride. Keep it proportional, don't go Italian. :D
    .
    Google CTE. here is a link, there are others. I live here on the Gulf, I figure all those oil rigs out there that are coated with it, must know something.
    http://www.epoxysystems.com/216.htm
    .
    What shaft length is the OB? The cav plate has to be just under the water. A motor well added at that height won't be hard to add to the stern, then clamp the motor on.
     

  15. dragonjbynight
    Joined: Apr 2008
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    Location: Indiana

    dragonjbynight Senior Member

    As i mentioned before, not a pro, but people always makes great suggestions, and adds to my lack therof knowledge. This has to be one of the best sites i have come across as far as range of knowledge.

    If you do decide to build it, would love to see pics of the progression.
     
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