Building Pontoons

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

  1. muddin redneck
    Joined: Jun 2009
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    muddin redneck DO IT IN THE MUD!!!

    i am wanting to build a small pontoon boat that has an open deck and a small cabin on in just big enough to sleep 2 and a dog. i was thinking 20' long and 8' wide for the deck. the cabin part would be 10' long and 5' wide. as long as the weather was nice and we could keep the skeeters away we would just sleep outside on the deck. a small grill or stove would be on the deck for cooking. we would bring enough food and water for 2 nights and 3 days. would this be a comfortable size for 2 people and a dog for a weekend camp out on there river or do i need more room? any suggestions on a bathroom area. as for the pontoon this is where i need some help. my first tought was large pvc pipe(18"+). then i thought maybe plywood and fiberglass. now im thinking about just fiberglass in a mold and then just pull out the formed pontoon. which idea would be the easiest for a beginner to build? i have never used fiberglass so i dont know how hard it is to work with. or would it be just as easy to try to find a set of old aluminum pontoons and just start there? what is the formula for figuring out how much flotation is needed and how much i would get out of each of these materials? any info would be greatly appreciated. thanks.
     
  2. Darce
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    Darce Junior Member

    There's quite a few old plans here
     
  3. muddin redneck
    Joined: Jun 2009
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    muddin redneck DO IT IN THE MUD!!!

    thanks for the site but none of the boats are quite what i was looking for. my main question is how do i build the pontoons pvc pipe, wood and fiber glass, fiber glass in a mold, or just try to find a set of aluminum pontoons already built. the fiber glassing part is what im worried about b/c i have never done it before and dont know the difficulty level or skill needed to make it work well.
     
  4. hoytedow
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    hoytedow Wood Butcher

    Why not build the pontoon deck scaled and cleated to fit a 3 man tent? It would save weight and wind resistance. Does the dog get to stay inside?
     
  5. muddin redneck
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    muddin redneck DO IT IN THE MUD!!!

    oh yea the dog stays inside!!! i did think about a tent a one point but it just wasnt quite what i wanted. i am wanting to drive the boat from the roof of the cabin, and i have never seen a tent that would hold me up lol. are there any mold that i could you to put fiberglass in and then remove to make the pontoons out of? i am kinda leaning towards buy an old pontoon boat fith deck damage or some other problems and going that route. as long as the pontoons were not totally messed up i could make them work. i would just pressure test they to make sure they didnt leak and if they did i would just weld the holes or cracks.
     
  6. hoytedow
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    hoytedow Wood Butcher

    Dear fellow Redneck, you can build the cabin structure out of wood with a plywood roof, and snap on canvas sides. You can even put big plastic picture windows in the canvas for better visibility, or only snap the canvas half-way up. You have a lot of options available. You may want to put a slight arch in the roof to help drainage.
     
  7. muddin redneck
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    muddin redneck DO IT IN THE MUD!!!

    thanks for the tarp idea. what about the pontoons? does anyone have a good idea or simple plans for building them? is fiberglassing difficult to master? i am know thinking about square flat bottom plywood pontoons and then fiberglassing them. if the 2 pontoons looked like 2 very narrow flat bottom jon boats could you get it up on plane? or are there any molds out there that you could mold fiberglass too and then remove? would a pontoon built out of fiberglass only be strong enough to support the weight of the deck and cabin?
     
  8. hoytedow
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    hoytedow Wood Butcher

    Yes, I built a 2 pontoon plywood flat bottom boat that planed very easily. Built it light, but strong. Of course I built mine way back in the early 1970's just big enough for 2 people. The whole thing could be disassembled and carried on the big Ford I drove back then. Alone, I could do 10 mph with a 5 horse motor. It was 8 feet long and had 2 2 feet wide hulls seperated by 2 feet of space. It was all bolted together with wing nuts and was very easily assembled/disassembled on the river bank.
     
  9. hoytedow
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    hoytedow Wood Butcher

    When I said canvas sides, I didn't exactly mean tarps, but, whatever...:)
     
  10. muddin redneck
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    muddin redneck DO IT IN THE MUD!!!

    yea you ment the 10-12 oz duck canvas right. do you have any pics or sketches of the boat you built? how hard is it to work with fiberglass? and did you stich and glue the wood(everybody on here talks about it but not sure what it intales)?
     
  11. Guest625101138

    Guest625101138 Previous Member

    For fully enclosed pontoons you will get good strength and adequate life from externally sheathed ply with fibreglass cloth. 200gsm cloth is all that is required because it essentially is there to protect the wood from sunlight and mild abrasion. It will hold paint a lot longer than unsheathed ply.

    The thickness of the ply will depend on the power and target speed. For displacement speeds up to about 10kts 12mm ply will be more than enough. The best shape will be a canoe style for these speeds. It will not require much power.

    This thread gives an idea of how simple it is to construct the hulls:
    http://www.boatdesign.net/forums/boat-design/camping-kid-build-raft-race-28311.html#post295409
    In your case the hulls will be heavier, bigger and fully enclosed. Screwing and gluing them is probably easier than stitch and glue for joining. The timber is providing adequate strength. Using simple chine and gunwale stringers with regular bulkheads will be adequate.

    Fully enclosed hulls like this will be quite strong.

    The deck can simply be made from 12mm ply sheets separated by 100mm bearers. You need to determine how you will connect the deck to the hulls and provide appropriate reinforcing in the hulls and deck to suit. Stainless brackets and bolts work well.

    With sheathing you need to round all the corners of the timber to soft curves of say 10mm radius. It is desirable to do as much with a single piece of cloth as you can but you are limited in how far the cloth can be curved before it creases. It is better to overlap with another layer of cloth than allow creasing. There is no need to vacuum bag any sheathing if you do not try to wet out cloth that will hang down. You do not want to try sheathing the complete hull in one go. May be possible to do bottom and sides in one step and then the deck.

    This gives some description:
    http://www.azom.com/details.asp?ArticleID=1105#_Procedure_for_Glass

    The peel ply is recommended if you want the minimum effort to get a good finish. If you want a nicely faired finish then you will also need to bog up the surface with a fairing filler and sand it smooth. A little time and effort here can result in a high standard of finish.

    There are heaps of references on sheathing and stitch and glue. With these hulls you should be able to do full length sheathing. I would probably do each hull in four goes - port side, starboard side, bottom and deck. This will provide double layer on the chine and gunwale. Extra wear layers on the bow are useful for beaching.

    If you want to push the hulls into planing regime then you have to look more closely at the hull loads and strength.

    With the hulls and deck all fully sealed you will have sufficient buoyancy in any of the three elements to float the weight. Hence very low risk of it actually sinking.

    Will take a few hours with cardboard and glue gun to make a model that will give insight into what it will look like and how to build it.

    To get the hull sizes you need to determine how much it is going to carry and make an initial stab at the hull weight. This will give the hull volume needed. Each hull should have enough buoyancy to float the entire weight. Stability can be a concern if this is not achieved.

    Rick W
     
  12. hoytedow
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    hoytedow Wood Butcher

    Rick Willoughby,
    Good answer, saves me from having to cover it. I used screws and glue since this was my first boat and I had not heard of stitch and glue yet. The hulls were open except for the bows which held air under short foredecks. The motor mount was mounted to the stern crossbeam with heavy angle braces. There was no tent or superstructure since it was used for day trips on the river. It was however very stabile and comfortable within its designed function. I am planning to build another one but right now am short on cash. When I draw up the plans the old fashioned way I may post them but right now it is low on my priority list. P.S. I used 1/4" plywood(approx. 12 mm) and the stringers were 1 by 2s(approx. 36mm by 72mm) softwood.
     
  13. muddin redneck
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    muddin redneck DO IT IN THE MUD!!!

    what are some good books or websites on how to stitch and glue a boat together b/c i have not idea what that really means? and i was wondering if i had my floation calculation correct. if my pontoons were 24' long, 18'' wide, and 12'' deep they would hold up 2246 lbs. each(I think).
     
  14. hoytedow
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    hoytedow Wood Butcher

    Mud-24 feetlong? How big is your pickup truck anyway?
     

  15. hoytedow
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    hoytedow Wood Butcher

    One cubic foot displaces about 62 pounds of water.
     
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