small stell boat

Discussion in 'Boat Design' started by ddraeg, Jul 23, 2010.

  1. ddraeg
    Joined: Jul 2010
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    Location: London, UK

    ddraeg New Member

    Hi, I have a number of pieces of steel salvaged from a houseboat remodelling job I did.

    I've not built a boat before though have renovated a few.

    My plan is to build a 13 foot flat bottom boat, 5 foot beam with a plumb bow. I have nearly all the steel, 6mm (1/4) for the bottom and 3mm (1/8) for the sides,

    The boat is to be used (and left) in the river (Thames) where I live. It's non-tidal and very flat. I calculate that with an inboard diesel the boat will draw 200mm (8") leaving a freeboard of 550mm (22").

    It'll weigh best part of a tonne, but that doesn't matter if she stays in the water.

    Can anyone throw any light on my plan, your welcome to scupper them!
     
  2. L.DOSSO
    Joined: May 2003
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    Location: FRANCE

    L.DOSSO Junior Member

    i think you can do a box with your metal sheets but not a "boat". 3m96 LOA is too small. It will sink. Adding an inboard diesel into it is just a larger dream..sorry.
    lucas.
     
  3. ddraeg
    Joined: Jul 2010
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    ddraeg New Member

    Errr? I have pontoons smaller than that made of steel and they ....er ........float!

    If it displaces the water relative to weight it leaves a reasonable freeboard, why would it sink? Are you aware of any deficiency in my welding perchance?
     
  4. wotsnext
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    Location: Staffordshire UK

    wotsnext New Member

    Good luck with that, I dont see a problem...but I'm no expert, more of a canal man myself, I'd love to build a 23' narrowboat...maybe one day. :)
     
  5. SKot
    Joined: Jul 2010
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    Location: Poland

    SKot S Kot

    Something like this?
     

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  6. wotsnext
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    wotsnext New Member

    She looks nice, our narrowboats tend to be a bit more boxy, many infact are built in Poland .
     
  7. L.DOSSO
    Joined: May 2003
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    Location: FRANCE

    L.DOSSO Junior Member

    following thoughts about ur boat

    hello again.
    I did a small drawing and i computed then..I think such boat will at least displace 500kg (perhaps 450 kg) of water. Then only the plating of sides and bottom will reach 320 kg. it means taht you have 180kg left for you (the weight of the captain) , a little bit of strucure, ,deck ,gunwales, and your engine and your d.o tank. So it is a little bit short. 6mm is too heavy... i think.
     
  8. ddraeg
    Joined: Jul 2010
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    ddraeg New Member

    6mm is the base, the flat bottom. The 3mm sides, bow and stern are plumb, straight up - and the boat is for flat water and never lifted out.

    The boat will have a plan area of 4m2 - at 250mm thats a tonne of displacement, given that overall I have 750mm sides I'd need 3 tonne to break the freeboard - OR am I missing something?
     

  9. L.DOSSO
    Joined: May 2003
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    Location: FRANCE

    L.DOSSO Junior Member

    i did not understand that you intended to do a box. Yes your calculation are good (exept with a box 1500 mm or 5 feet for breadth) i find 1500 kg of water displaced ( 4000 *250 *1500) or (lwl*draft*breadth).
    What i tried to do before was something that looks like more a usual hull shape.
    i did a preliminary sketch of what could have been line and i arrived at the calculations mentionned in the preceeding message. But with this idea of doing less simple form , true you would have had a more complex sheet shaping and forming process and maybe very hard to do). I hope you understand what i say ( my english).
    So good luck for your "boat" . bye
     
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