pontoon boat

Discussion in 'Boatbuilding' started by cat chaser, May 5, 2002.

  1. Guest

    Guest Guest

    mini pontoon boat

    Say cat I already have one. and your right it is the poor mans TRITON. Drink a couple of beers and think it out, if you don't get it let me know. I'm 250# and my buddy is 320# we have taken it out on very windy days - with white caps - way to much gear and had no problem. It is nice because when you gotta take a leak there is no problem. STABILITY!! but not much on looks. To bad your not in Texas!
  2. midnightkayaker
    Joined: Feb 2003
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    midnightkayaker Junior Member

    I believe you still have an overturn problem. One ten foot length of 10" (I believe thats outside dia.) will provide 340#s of bouyancy. Plenty, until you stand on the side and begin to hoist a net load of squirming fish. Keep in mind that on a pontoon boat your weight will be shifting around above the center of bouyancy, and out near the side you can generate a pretty strong moment arm. As your weight moves soley onto one pontoon, the other may lift out of the water, putting the entire load on one pontoon, which may sink, and over you go. Pontoon boats only work well if there is gads of reserve bouyancy, or you don't plan on shifting your weight around. If you are a heavy set person, catch a load of fish or catch an unfavorable wave at the wrong moment, you could easily roll a boat as narrow as you've described.

    You might consider a hybrid, build a punt and mount the tubes high on the outside. When you move to the side of the craft to haul your net you will have that 340#s of reserve bouyancy stabilizing the craft. With your weight acting below it, it will still be a righting moment instead of an overturning one. With such a configuration it might just be impossible to roll with just your body weight no matter where you stand or what you're doing. The punts really are easy to put together and if you design the sides high enough and mount the tubes outside the gunnels then they could fit above the wheel wells of your pickup when the craft is loaded in the bed. The pontoons will be out of the water under most conditions so the only detriment will be windage, and eek...style. Be sure to leave a few inches of freeboard above the pontoons. Keep in mind I'm just a civil engineer and not a naval architect.
    good luck with it, sounds like fun.
  3. audredge
    Joined: Apr 2003
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    Location: Nome, Alaska

    audredge New Member

    I've obtained some 55 gal plastic drums and am also trying to build a pontoon boat.Wondering if the use of PVC pipe for the frame is possible?Also wondering how to calc the weight capacity of each drum. This is going to be an offshore gold dredge so it has to be stout! Would appreciate any help!
  4. Mike D
    Joined: Sep 2002
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    Mike D Senior Member


    This should help. I imagine that you aren’t into math so you’d like the minimum of calculations, I doubt if you’ll find anything simpler.

    As you are in Alaska I also assume you prefer Imperial units not metric. So I would suggest you do your calculations in feet. One cubic foot of fresh water weighs 62.4 lb and salt water is 64 lb.

    Let’s say a barrel is 2 ft diameter and 3 ft long and so the total cross-sectional area is Pi.r^2 i.e. 3.142 x 1^2 = 3.142 and say it floats with a draft of 8 inches. The ratio of draft/diameter is 8/24 = 0.33, read along the base of the chart to 0.33 and read up to the line and read of the value of the area proportion on the left. The answer is about 0.29 and the actual value by calculation is 0.2918

    This is the proportion of the total area i.e. 3.142 x 0.29 = 0.91 sq. ft. is the actual immersed area. The buoyancy per foot of length in fresh water is 0.91 x 62.4 = 56.8 lb/ft and the barrel would be times 3 or 170.4 lb

    If you want to do the detailed calculation there are dozens of sites, go here for a good one http://www.efunda.com/math/areas/CircularSegmentGen.cfm

    Hope this helps you.


    Attached Files:

  5. audredge
    Joined: Apr 2003
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    Location: Nome, Alaska

    audredge New Member

    Thanks Mike!Useful Info
  6. redman
    Joined: Mar 2004
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    Location: Texas

    redman New Member

    Barrels for a Pontoon Boat

    I too am about to build a pontoon boat out of plastic barrels. I need your comments and suggestions as there aren't many plans out on the web.
    I have 6 50 gallon plastic barrels. My thought is to use electrical conduit bent into a half circle to surround the barrels as they sit in the water. (I'm thinking 2 per barrel ought to do it). Across the top, I want to use 2" conduit for cross braces. To that, I'll attach 3/4" exterior plywood.

    Here's another thought - your comments welcome - I'm wanting to use thin guage metal roofing along the sides of the barrels to streamline water flow and to improve the looks. I'm concerned about the blunt front end of the boat so I'm thinking I could "bend" the metal roofing cover in a shape like this:
    " _____/ ". If I do this, I'm not concerned about waterproofing the cover. The barrels will provide the flotation. My thought is that the smooth straight edge of the metal roofing cover will improve my flow through the water.

    Any thoughts? Any drawings out there?

  7. duluthboats
    Joined: Mar 2002
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    Location: Minneapolis,MN, USA

    duluthboats Senior Dreamer

    Is this for a raft or are you planning on putting a motor on it. Around here it is common to use plastic barrels for floating docks. Usually you build a frame from treated lumber; the frame is gapped so it straddles the barrels. The barrels are held in place by plastic banding. Then some type of decking (usually cedar) is applied to the frame. This works great for docks; I could not advise using it for a pontoon with a motor on it.

    Gary :D
  8. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Electrical conduit is very weak stuff, even "rigid" is not very strong. EMT is much better strength wise, but a rather poor choice in building material as the marine environment will eat it up in no time.

    Why must you vary the ways laid down by well experienced and educated folks whom do this sort of thing for a living?

    Pontoon boats are cheap. Finding one that needs a deck or engine can be very cheap. The engineering is done for you and you only have to fix it, which is quite the difference than designing it . . .

    If this is a floating platform, then pick up a copy of the currently available Woodenboat magazine (April) and look at pages 28 - 31. The thinking is done, just build and you can use your drums.

    DAVID COX Guest


  10. GEORGE L.

    GEORGE L. Guest

    IF WORKS LET ME KNOW GeorgeLee@chi-caritas.org

    how do you plan to attach deck to PVC
  11. duluthboats
    Joined: Mar 2002
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    duluthboats Senior Dreamer

    This is for BHudson.

    Attached Files:

  12. Marten

    Marten Guest


    Hallo Everyone.

    Sorry for my bad english, but I have to write.

    I'm also into building a pontoon. I want a small one to have when I'll go fishing. Thinking on building one like:


    I found that one on walmart.

    I'm planning to make the pontoons with stich and glue (Epoxy), with thin playwood.

    I'm thinking on attaching oars just like the imagelink.

    Now to my question:
    Anyone have any idea on how big they have to be? I'll not be standing up in the pontoon but it has to be a little stable so I don't have to swim.

    Anyone have any pictures with homemade pontoons like this. If so I would apriciate to have a look.

    Feel free to email me if anyone have any pics or drawings or plans or anyting helpfull:


    Thanks everyone in advance.

    / Mårten, Sweden.
  13. BOB1972
    Joined: Jun 2004
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    BOB1972 New Member

    I have just recently received a large quantity of aluminum from a sheet metal fabrication company that went out of business. I would like to build a 4x8 pontoon to fish from, and it seems from my calcs the sheet aluminum that I have is quite a bit heavier than what is used in other pontoons boats that are built. Along with this it will not carry as much weight as I would need.

    The sheets of alum that I have are 48x48x 0.16. I have found a good fabricator that can make them round. a 48x48 will make approx. a 15.25" diameter pontoon. with that being said the tubes would have to be much longer (than 8') in order to carry the loads that I need plus a safety margin. the chart that you have shows a drag ratio, is this the standard for the tube to be submerged 1/3 of the diameter while loaded? my other question would be if I did make the 15" dia pontoons, say 11' long and welded a secondary 8" tube along side each of them would that hender the manuverabilty? make it more stable?
    Thanks for any responses
  14. dsfi
    Joined: Jun 2004
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    Location: Indianapolis

    dsfi New Member

    Hi all,

    Does anyone have any links to buy actual pontoon aluminum floats? Like the original pontoon parts at good prices?

  15. ScourtU
    Joined: Aug 2004
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    Location: mn

    ScourtU New Member

    I built a 4 x 8 pontoon

    I have built this "contraption" as some would call it. I used 1 sheet of good non treated plywood 3/4 inch thick. For flotation i used something as light and as bouyant as possible. 2 inch foam! I cut 4 full sheets of foam 16 inches wide and got 12 pieces. i used spray adhesive to bond them together and applied them to the bad side of the plywood. I then used a piece of nex-wood 3 1/2 inches wide and long enough to go from the rear of the foam and attach to the front of the plywood to use as skidders so the foam wouldnt get chewed up beaching. I then used carriage bolts to squeeze the nex-wood, foam, and plywood together. I used an electric chainsaw to slightly round the edges and to form the front of the pontoon. I smoothed it all out with a belt sander.It is kind of in that order but whatever. Next step was paint... exterior paint works painted the whole thing dark green. i attached 2 spindel seats on top, 1 mushroom anchor, and a simple eye bolt railing system with rope through it to stop anything from getting kicked overboard. I use a foot controlled trolling motor and a big deep-cycle battery.I cut a "sporty" tunnel hull looking front end on it and attached 2 oars to the edge of the plywood. I have had it out twice now on the mississippi river and it does fine. looks cool and floats in 6 inches with all equiptment and my skinny behind on there which is 140. The boat without the battery and motor and seats is literally no more heavier than just the original plywood. I would say less than 100 lbs and can get most likely over 500-600 lbs before the deck hits water. But unless you are a drunken fool it wouldnt have to carry that much weight. I use my mini van to transport the "contraption" to the river and i just slide it in and slide it out of the back of the van. Way lighter without the battery than with it while loading and unloading. Even my co workers think i did a really good job and even wonder what posessed me to build it. Simply put, i wanted a good fishing boat that didnt need a trailer and light enough for 1 man (mainly me) to load and unload. There you have it...MY VERSION of a perfect fishing boat. Im thinking of calling it Foam-ula 1. Ha-Ha... Thanks and hope this helps every home boatbuilder out. i wonder if there is a place where i can post a pic... Thanks ....Mike
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