Building Pontoons

Discussion in 'Boatbuilding' started by muddin redneck, Sep 12, 2009.

  1. Guest625101138

    Guest625101138 Previous Member

    The idea of stitching is more often replaced with external jigs these days. Rather than wire stitching the cut pieces together, they a formed up in the jig and glued/glass taped internally. This is a photographic explanation using home made sandwich flat panels (boat forming about halfway through):
    http://picasaweb.google.com/adventuresofgreg/ExpeditionBoatBuilding#
    This one uses factory formed sandwich panels but same method of joining the sheets:
    http://www.boatdesign.net/forums/boat-building/my-little-piece-peace-25962-10.html

    The same method can be used for joining pieces of ply to form a hull. In your case it is likely to be easier to use stringers in the internal corners rather than glass tape.

    What speed are you hoping to get from the boat and what power do you have in mind?

    Rick W
     
  2. muddin redneck
    Joined: Jun 2009
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    Location: Muscatine, Iowa

    muddin redneck DO IT IN THE MUD!!!

    for the first time in my life the speed doesnt really matter to me. the boat is going to be used in the mississippi river for a weekend camping out boat for me and my lady and our dog. once i get where im going to spend the weekend it will be anchored and left there, while i run around in a small flat bottom boat. as for the motor i was thinking something small with about a 5:1 gear reduction with about a 13'' prop(because i have one). now the stringers your talking about do you mean use like 2x2 lumber for a frame (internal skeleton of the pontoon so to speak)and nail or screw the to plywood to that and then fiberglass it, or am i waaaay off.
     
  3. muddin redneck
    Joined: Jun 2009
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    Location: Muscatine, Iowa

    muddin redneck DO IT IN THE MUD!!!

    hoy
    this boat is going to be in a marina and only trailered in the winter months. i am wanting to camp out on it in the mississippi river.
     
  4. Guest625101138

    Guest625101138 Previous Member

    You are close with the stringer size. I would use even smaller - say 1.5" square. Screwing with stainless screws is better than nailing it. They need to be countersunk for glassing over.

    For slow speed up to about 10kts on a 24ft hull the canoe sterns will work well.

    You should be able to build the whole thing with a loaded displacement of 1 tonne if you keep the cabin simple. The hulls 24ft long and 16" square section. In plan the hulls would have a gentle curve from maximum beam in the middle coming to a point at stern and bow. If you wanted to get fancy you could taper the sides outwards from bottom to deck but it adds complexity. It is desirable to have a bit of rocker forward so the boat will glide up a beach easier if that is something you are likely to do.

    I would be looking around for a good 7 to 10HP outboard rather than trying to put something together just because I have the prop. You could expect 10kts from 7HP. A 10HP will have some reserve at 10kts.

    12mm (1/2") ply is quite heavy for this. You could get away with 3/8" but it will not take as much punishment. I would not go down to 1/4" as it will need careful use. With 1/4" it will not be a robust hull unless heavier glass is used.

    Rick W
     
  5. hoytedow
    Joined: Sep 2009
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    Location: North of Cuba

    hoytedow Wood Butcher

    simple pontoon boat from long ago.

    Just a quick sketch.
     

    Attached Files:

  6. hoytedow
    Joined: Sep 2009
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    Location: North of Cuba

    hoytedow Wood Butcher

     
  7. rozerdemit1
    Joined: Jan 2010
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    Location: london

    rozerdemit1 New Member

    Really good answer thanks for sharing this with us,,,,

    party tents and marquees
     
  8. Boilermaker
    Joined: Jan 2010
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    Location: Ford, Wa, USA

    Boilermaker New Member

    total water displacement

    I believe your calculations are for a equal amount of water displacement. If you do not want the pontoons completely submerged you have to calculate the volume of water displacement (gallons)(weight) of how much of the pontoon you would want submerged. Usually half on most pontoon set ups. Just my 2 cents worth. Steve
     
  9. joefaber
    Joined: Sep 2005
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    Location: san francisco

    joefaber Junior Member

    Mud - look over the attached PDFs.

    just add an eight foot section to the middle of the PM Platfrom boat
    and build a cabin based on the PARTI-O boat design.
    you'll have the boat you described.
    add another 12" to the pontoon height,
    keeping the bulkheads proportionate,
    will give you LOTS of floatation.

     

    Attached Files:


  10. hoytedow
    Joined: Sep 2009
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    Location: North of Cuba

    hoytedow Wood Butcher

    Correction: metric conversions were twice the accurate number. 12mm should be read 6mm and 36mm should be read 18mm.

    Sorry about that.
     
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