Foam pontoons?

Discussion in 'Boat Design' started by Ron Skelly, Feb 27, 2014.

  1. Ron Skelly
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    Ron Skelly RonS

    I am planning on using foam pontoons covered with the appropriate epoxy & glass for this small boat project I am working on. Are there any negatives to this approach?
    RonS
     
  2. messabout
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    messabout Senior Member

    Tell us more about the intended boat, Ron. There are reasons for and against that kind of build. Depends a lot on what the intended purpose of the boat will be.

    For a sizeable boat, glass over foam is an expensive way to do it because it will need lots of glass and epoxy and some good quality foam that you will not be able to get at the big box stores.

    For a small pond boat the method will work fine and may be reasonably cost effective.

    You mention pontoons so it would seem that you intend a catamaran type. You will need some pretty stout bulkheads to which you will fasten the crossbeams. That implies that there will be framework of one sort or another. Plan carefully for this. The integrity of the connection is important because there are some pretty severe strains placed on them when in a bit of a chop or crossing wakes.
     
  3. Ron Skelly
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    Ron Skelly RonS

    Thanks...yes it is a very small boat..13 feet long...it will be a tri-hill - 3 pontoons so there is lots of stability.
     
  4. Ron Skelly
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    Ron Skelly RonS

    I have worked out the load capacity using the water displacement formulae and it should be able to easilly carry an adequate amount of weight.
     
  5. Fanie
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    Fanie Fanie

    Geeeez Ron, we have a bloke here by the name of Manie, he also build these barely floating things if-you-cough-it-goes-under if you know what I mean :D

    What exactly is it you have in mind ? Stating 3 hulls is really vague... ?
     
  6. Ron Skelly
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    Ron Skelly RonS

    Fanie...can I see some of Manie's work with foam?
     
  7. Petros
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    Petros Senior Member

    usually building plywood stitch and glue, and than glassing over it is cheaper and faster than carving solid foam pontoons. and it gives you some internal storage space inside the hulls. the lowest cost way to build is skin-on-frame, just enough of a wood frame to hold the fabric skin in place. and you can use fiberglass skin, or now more commonly (and far less costly) is to use nylon or polyester fabric, and than oil based paint or polyeurethane finish to seal the weave.

    Or are you thinking solid foam, or sheet foam? why would you go solid foam? very costly, adds weight and you loose the internal volume.

    what kind of boat is this? fishing, sailing, row boat?
     
  8. Ron Skelly
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    Ron Skelly RonS

    More like a 13 foot long raft with some unique characteristics. Just for cruising on small lakes and rivers.
     
  9. Fanie
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    Fanie Fanie

    Manie doesn't work with foam, he sleeps on it ;) I was referring to his (and your) version of big.

    If I was you I'd look for something like an old hobie cat and use that for a starting boat instead of building something. The efficiency of a hull is very significant especially when you use an electric motor, and something like the hobie is not too bad. You can even space the two hulls differently for different types of venues.

    On any water you will appreciate a tiny bit of size when it gets windy and choppy.

    Petros is right, solid foam is like a drum, it just floats, is heavy and doesn't want to go anywhere. It is also a lot more work than most appreciate, shaping the foam, glassing it etc - all kinds of unforeseen little problems - most okes never complete their project.

    Unless you are trying something new to experiment with, I'd say get something existing. That is what I would do.

    There is no such thing as too much flotation, you need to calculate what you want to carry with LOTS and LOTS to spare, if you weigh 80kg and the hull can float 100kg and you go down with a swell then the momentum is going to sink the hull completely under water, probably capsizing too.

    Since I suggested something like a hobie, ask someone with one to take you for a spin, you'll get the idea. There should be some around. Sailing is a lot of fun too.
     
  10. Manfred.pech
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    Manfred.pech Senior Member

  11. joebehr
    Joined: Apr 2014
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    joebehr Junior Member

    just wanted to add my $.02...I have a 13' aluminum pontoon boat that needed more weight capacity in the very front since we use this boat for lake fishing more than cruising. I used 1.5 lb EPS foam and added a 3rd pontoon which increased floatation & improved steering greatly. I will give photos and detail if desired.
     
  12. joebehr
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    joebehr Junior Member

    Sorry...wrong photo files...give me a minute...
     

    Attached Files:

  13. joebehr
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    joebehr Junior Member

    another pix
     

    Attached Files:

  14. joebehr
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    joebehr Junior Member

    This project was very simple and cost about $250 for the foam block, epoxy resin and mounting hardware...works well and does just what the boat needed.
     

  15. boatbuilder41
    Joined: Feb 2013
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    boatbuilder41 Senior Member

    I can see where that would make a big difference 'I'm gonna start a similar project soon
    I think I'm gonna go with hollow fiberglass pontoons........ not sure yet. It really depends on customer preference. You can only do what you are paid to do... but I will recommend this thread to further his education on this type of modification.......
     
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