Fishing/Hunting pontoon boat

Discussion in 'Multihulls' started by bmack, Jul 3, 2007.

  1. bmack
    Joined: Jul 2007
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    Location: Southern Ontario

    bmack Junior Member

    I want to build a pontoon boat that can be broken down without much hassle and transported in my van... I am planning to fish and use it as a blind for hunting... I want it to be somewhere in the range of 8' long and 5' wide... does anyone have any ideas... what I have so far is I will get some ventilation tubes and seal and fill them with foam for the floats and make a wooden plat form to bolt to them... I will also be using a small electic motor on this... if anyone has any ways I can improve upon this or do something differently please let me know...

    Thanks

    Brandon
     
  2. bmack
    Joined: Jul 2007
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    Location: Southern Ontario

    bmack Junior Member

    Now I am thinking for the pontoons to just buy foam from HD and layer it to make it a foot thick then cut out the shape and fiberglass it... what do you guys think about this and how would i go about fiberglassing it...

    Thanks


    Brandon
     
  3. bmack
    Joined: Jul 2007
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    Location: Southern Ontario

    bmack Junior Member

    Now I am thinking for the pontoons to just buy foam from HD and layer it to make it a foot thick then cut out the shape and fiberglass it... what do you guys think about this and how would i go about fiberglassing it...

    Thanks


    Brandon
     
  4. messabout
    Joined: Jan 2006
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    messabout Senior Member

    If you buy foam from HD it will likely be styrene variety. If so then polyester resin will melt the foam into a gooey glob almost immediately. That kind of foam is also bad about soaking up water. According to Murphys' law, water will get to it somehow. If that is all you can get your hands on, then you will need to use epoxy for the laminate covering. Epoxy costs more but is more reliable in most cases.

    The most sensible way to make the folding boat is to use plywood. Just two boxes with ends pointed and joined (bolted )together at the square ends. You'll need to make four of them. That will make a useable float boat that has pontoons. Best if you make it a little longer than you suggested. Say ten feet. A box 12" wide by about 16" high will do. If each box is 5 feet long it will support about 120 pounds at 6 inches draft. That includes loss of displacement at the pointy ends. Four of those and you'll have a potential displacement of 480 pounds. That'll support you, the boat itself, your dog (unless he is a giant Newfoundland), a battery and an electric troller. It will be hard to turn unless you put a little bottom rocker in the pointy ends. Say about 4 or 5 inches of rise at the four ends only.

    Plywood boxes are nearer to a sure thing than trick foam and FRP. Not as messy and smelly either. Plywood is a quick and dirty build that wont cost much. If you tire of it, just take the top off and use it for A flower planter, a hog trough, or fuel for a campfire.
     
  5. inventing_man
    Joined: Jun 2007
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    Location: mo

    inventing_man Junior Member

    Another option to epoxy is to Rhino line ..truck bed liner spray (spray polyurethane ) the foam pontoons . Use a good piece of 2X4 ceder for a back bone stiffener in the foam and for an attachment place for the deck. Foam will absorb water but only a very slight amount nothing to worry with ..it'll float.
     
  6. jimith
    Joined: Jul 2007
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    Location: pittsburgh

    jimith Junior Member

    Brandon, you may want to look at my posting in Boat Design. I posted it July 14th. under Building My Own Pontoons.
     
  7. jimith
    Joined: Jul 2007
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    jimith Junior Member

    I'm glad you like the pontoon. The whole idea is that the pontoons are detachable. I can change decks depending what I want to do.

    A simple plywood deck 5'x4' will be the first. I want to make a 6" drop design, like a u, between the pontoons to give me a lower center of gravity. Just for kicks, I want to cover the drop u design with a body like an air foil and steer with a steering wheel.

    If you have a trailer the pontoons can be fitted with a 5' or 6' wide deck for more stability. The aluminum I used comes in a 4'x10' sheet. You could make the pontoons 10' for more capacity.

    I have read of so many people wanting to know how to make pontoons. I think this is an easy build, and very sturdy. Plus the two pontoons at full draft will hold 960 lbs.

    The total cost including the deck should top out at $350.00. Plus, I just wanted to see if I could build the thing. Good luck on your boat. Hope I gave you some ideas.

    jim
     
  8. bmack
    Joined: Jul 2007
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    Location: Southern Ontario

    bmack Junior Member

    Thanks Jim, yeah thanks for the ideas... if I can find a place around here that I can get aluminum for a good price then I will make my own because of the flexibility on deck design... as I mentioned above I want to use this for a blind and the flexibility is great... BTW how much do the finished pontoons weigh and what thickness of aluminum did you use...

    thanks

    Brandon
     
  9. Guest625101138

    Guest625101138 Previous Member

    The attached shows a boat that is 12ft long made from a single sheet of 1mm thick aluminium. I have made a few boats like this from aluminium sheet. The advice I can offer is.

    1. Try to get a pointy bow or a gentle upward curve of the hull at the front as this will make it much easier to push through the water with an electric outboard. There is a compromise because you loose volume but a bluff bow will be very hard to push.

    2. You can get quite nice shapes if you know how to develop plate. Experiment with cardboard before you start. Don't forget to allow for seams.

    3. For watertight seems it is better to sandwich the edge of the sheet between strips of thicker aluminium.

    4. You can get sealed aluminium rivets but I mostly use plated screws and avoid saltwater.

    5. You can get polyurethane glue that expands as it dries and is very tough. It is the best way to get waterproof joints. This glue is compatible with polystyrene foam if you want to use this for internal bulkheads. It is much easy to work then wood and will provide some solid buoyancy if the thing leaks badly.

    6. You can also get close to waterproof joints using soft rubber strip. This is available in rolls with tape 3mm thick and with glue on one side so it stays in place during assembly.

    7. You can get nice straight edges along an open seam using square tube to support the edge.

    8. I have used as thin as 0.6mm sheet but it can be punctured and dented quite easily. The 1mm sheet is quite robust and will take a bump. I think for your aplication 1.6mm (1/16") would be good enough. In Australia we cannot get marine sheet less than 1mm thick.

    9. You can cut the thinner stuff with shears but it stretches the edge. Jig saw or circular saw with a fine tungsten blade is good. I have even used a thin metal cutting disc with a straight edge. Much faster than jigsaw. For your 8ft hulls you should be able to avoid a lot of cutting.

    10. When bending it is better to clamp along an edge or fold the edge to stiffen it before bending the sheet. It is easy to buckle the sheet if the bend is not done evenly along the bend line.

    11. Allow relief on the corners of bulkheads as you can never get a really tight crease and it is realy not required unless you are making a seam. With a seam you can square up using a wooden mallet. The dents will be hidden.


    Rick W.
     

    Attached Files:

  10. bmack
    Joined: Jul 2007
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    Location: Southern Ontario

    bmack Junior Member

    Thanks for the info Rick... BTW does anyone know how I would bend 8 feet of 1.6mm aluminum... anyone know of some home made breaks or anyway to bend it without one... maybe using some 2X4's and some hinges...

    Thanks

    Brandon
     
  11. jimith
    Joined: Jul 2007
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    Location: pittsburgh

    jimith Junior Member

    Brandon, the pontoon weighs 35 1/2 lbs with the 12" sheeting. I would think the foam sheets that I will fill the pontoon will add a few more pounds.

    A 3/4" 4x8 sheet of plywood should weigh about 60 lbs. A lot more than I would have guessed.

    The aluminum is .04 inches thick. I have attached a close up picture so you can get an idea.

    Rick is right about making the pointy ends, but I need to get to the point that I can test a few things first.

    With a bulk head at each end you can always drill out the rivets and add any desing cap to the ends at any time.

    For bending your aluminum look first at a self owned car body shop. They may have one. I am about a half hour between two race car builders. They both had brakes. Heating and cooling businesses that make their own duct work may help.

    To bend it yourself you will need an 8' table. Place the aluminum on the table with 1' hanging over the edge. Clamp angle iron ontop of the bend mark and clamp it. How? That is the trick. No 2x4. You have to have vertical support on the top clamp.

    If you get it clamped, start with a 2' 2x4 bending the aluminum MOVING ALONG the bend edge. If you don't you will crease the aluminum. Don't make too mutch of a bend at one time. When your near 90 degree bend start using a hammer on the 2x4. You can use the hammer in the beginning, but not too much bend at a time. Practice on a smaller piece first.

    Also, I just tested my pontoon in my pool. The first thing I noticed when adding weight is that the pontoon wants to roll over VERY EASY. I will have to secure the pontoon so no rolling. At 185 lbs the draft was 5". So much for my drop deck design. I was hoping for a better draft, but just crunch the numers, the add up!
     

    Attached Files:

  12. Guest625101138

    Guest625101138 Previous Member

    Jim - How wide have you set the two hulls? I would expect that you could make it stable enough to stand on.

    BTW 0.04" is 1mm. This will show bumps but should be hard to hole. Each pontoon will be easy to manage weight wise.

    Brandon - From a boat perspective the best performance for an all-up weight of 450lbs comes from hulls 16" wide with a pointy bow about 14" long. A 1HP outboard would get 5kts. Performance is best with the hulls set wide apart. These would sit 4" deep.

    The width of the transport vehicle does not have to constrain the width of the boat. If you can load 8ft long pieces then you can make the overall width 8ft. There is nothing wrong with having the deck wider than it is long. Alternatively you could use two or three deck pieces.

    It would be possible to make two 6" square by 8ft long cross beams from a single sheet of aluminium. Large X-section equates to good torsional rigidity. These could be used to support some lighter ply.

    Keeping the hulls low wil help stability. If the potoon is for smooth water then you could make a complete pontoon hull 15.5" wide and 8" high from a single sheet with a single seam. Will only sit 4" above the water though with two people on board.

    The thickness of the sheet will obviously affect the cost and weight. 1mm sheet 4 x 8 weighs 17lbs. I think 1mm sheet will be robust enough. It will just dent more readily than 1/16". 1mm is quite easy to bend by hand providing you can clamp the sheet. I use 2" square steel tube with 1/4" wall for clamping if it is only clamped at the ends. 2" x 4" timber is OK for clamping if it is clamped along the length. Probably need 4" x 4" timber if it is only clamped at the ends. Not sure if you can bend 1/16" by hand.

    Rick W.
     
  13. jimith
    Joined: Jul 2007
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    Location: pittsburgh

    jimith Junior Member

    Rick, I need to carry the boat inside my Ford explorer. I have 4' wide, but need to give myself a few inches. I was thinking between the inside of the pontoons to be 20". That would give me 44" total width. I am just worried when turning in water, the pontoon doesn't want to roll out from under the deck.

    jim
     

  14. Guest625101138

    Guest625101138 Previous Member

    I am not certain I understand your problem with the pontoon rolling out from under the deck. It should be a simple matter of fixing them in place.

    The point about the width is that you could make a three piece boat with a deck and two pontoons. All able to fit in a 4 x 8 area when carried individually. When assembled the deck would sit 8ft across rather than 8ft along. I expect that you could stand anywhere on this deck without the whole thing tipping. If you make the deck 8ft long and 4ft wide you are likely to tip if you stand on either side or even on either end. So a wide deck will have all usable area. A long deck will be limited to around the centre section.

    Assembly of pieces can be made very quickly without tools just a little creativity and some bits from the hardware.

    Rick
     
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