Question about my pontoon boat design

Discussion in 'Boat Design' started by noi noi, Apr 6, 2009.

  1. noi noi
    Joined: Apr 2009
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    Location: Australia

    noi noi New Member

    Hi everyone.

    I am just starting the process of building a housboat/pontoon boat. I have bought some floatation pods that I assume are normally made for jetties and docking stations.

    The pods are made from a heavy duty plastic and filled with a high density foam. The basic shape could be described as a 1.2x0.6m top with a 1.0x0.4m bottom prism. They have a flange around the top for bolting wood/steel/aluminium beams onto so as to make an easy platform.

    I have 8 of these pods and 2 larger pods. With the ability to make 2 pontoons 6m long each.

    The 2 larger pods are wider and deeper. The guy I bought them off convinced me that because I would have more weight at the back I should get the 2 bigger pods and put them on the back so the whole boat turns out level.

    He also said that having them on the back would give me better steering.

    Is this sound knowledge? Will I have better steering?

    Or will I have much worse drag?

    Is it worthwhile having more drag to increase steering ability and get the boat flat with more weight on the back?

    I realise these pods aren't really design to move. Due to the shape there is a gap between each pod. And the front pod is a flat surface. Not exactly great for cutting through the water. However, i don't need to go fast. But I am concerned about needing to increase motor size and all that due to it being a brick...

    I may have the option to swap the bigger pods for 2 more of the same size. Should I do this?

    Thanks. Alot of questions...
     
  2. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    A boat is generally balanced with most bouyancy in the middle, and weight added in the form of structure and cargo should be balanced as well, and concentrated amidship.
    Of greater concern is a blunt bow and uneveness along the bottom and sides. Gaps between floats will cause havoc with hydrodynamics at any speed.
    Polyethelene floats can be filled with foam or air. I am now rebuilding a dock with the air filled type. After 10 years underwater half the time, and always out of the sun, they have distorted quite a bit, though they are still servicable. I've seen kayaks do this too, so it's not that rare a problem. In your case, be aware they do not have infinite lifetimes. Thery must be replaced eventually, maybe in ten years.
    Your description of dimensions and shape confused me. Could you draw a picture?
    Since you've already bought your floats, you are obviously commited. I hope they will work for you.
     
  3. noi noi
    Joined: Apr 2009
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    noi noi New Member

    I'm not feeling super confident about them now which is why i'm posting I suppose.

    [​IMG]

    Thats a rough version. Since i'm going to spend a decent amount of cash from here on in I don't want to start with a crap foundation. This guy who sold them to me showed me his houseboat and sure enough it floated and was steady and stable.

    Guess i'm just a bit worried this thing is going to be too much of a brick to push around. Especially since I have lofty ideas to go all electric. Motor and all.

    I guess I was just stoked his boat looked nice and that it floated. Also that these pods won't sink even if they spring a leak in one and they looked easy to bolt together.
     
    Last edited: Apr 8, 2009
  4. noi noi
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    noi noi New Member

  5. alan white
    Joined: Mar 2007
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    alan white Senior Member

    Looks like a rather clumsy beginning for a hull that moves efficiently. You end up with gaps along the sides and bottom. even small irregularities tend to slow you down. You should build a nice dock for your future houseboat.
     
  6. noi noi
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    noi noi New Member

    Hehehe. Damn hey. Thats how i'm begginning to think to....

    I did have the idea to skin them where the gaps are and fill the gaps with polystyrene or something?

    And also build a pointed front?
     

  7. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    Yeah, I wonder what might cover the gaps. Did you know the stuff can be welded? It can, it's done all the time.
    Then every other one could be cut and you'd have a smooth hull. The bow(s) could be figured out I'm sure. More welding, sort of like the aluminum pontoon bows are done.
     
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