Smallest practical size for a steel boat?

Discussion in 'Materials' started by alanrockwood, Apr 2, 2010.

  1. alanrockwood
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    alanrockwood Senior Member

    What is the smallest practical size for a steel boat?
     
  2. Angélique
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    Angélique aka Angel (only by name)

    You might find some answers to that in the replies in this and this thread.

    Cheers!
    Angel
     
    Last edited: Apr 2, 2010
  3. MikeJohns
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    MikeJohns Senior Member

    I've seen Dutch boats around 10 feet in length in steel that were very nice but heavy, you would need a trailer and ramp to get them in and out of the water.
     
  4. Tanton
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    Tanton Senior Member

    Small Steel Cruising Boat.

    24'? Bigger the better.
     

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  5. Angélique
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    Angélique aka Angel (only by name)

    Yes, for example, a little bigger, steel 'Gieterse punter' which is traditionally build in oak.


    Gieterse Punter 580 build from 4mm steel sheet (2-4 hp auxiliary). More info and models here.

    Giethoorn Holland (Gieterse Punters)




    Good luck!

    Angel
     
    Last edited: Apr 2, 2010
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  6. Wynand N
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    Wynand N Retired Steelboatbuilder

    I assume you are referring to a cruising sailboat and I would say 24 ft LOA.

    Open boat / dinghy about 6ft.
     
  7. alanrockwood
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    alanrockwood Senior Member

    I was thinking of something along the lines of what Angel was showing a couple of posts previous to this one.

    My dream would be to build a replica Dutch barge and use it to cruise the canals of France.

    This dream of building a Dutch barge is not a realistic dream. However, it would be realistic to consider building a small boat, and then if that went well to consider building a second somewhat bigger boat, i.e. some kind of motor cruiser.
     
  8. froudedude
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    froudedude Junior Member

    I would think that size would not as much as a consideration as working the metal. shipyards have sizable equipement to bend or curve the steel and/or jiggs to torture it into shape. Really as long as you displace more than it weighs and can push it ...
     
  9. Landlubber
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    Landlubber Senior Member

    Yep, the 24 feet seems to be about it too here in Australia, certainly they can be built any size, but the 24 feet length seems to be about it. Plate thickness, weldability and weight are the factors that determine this.
     
  10. alanrockwood
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    alanrockwood Senior Member

    Yes, old thread I realize. Following up on the weldability issue, what is the thinnest plate that is practical to weld using a stick welder?
     
  11. MikeJohns
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    MikeJohns Senior Member

    4mm is the practical limit.
     
  12. M&M Ovenden
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    M&M Ovenden Senior Member

    Why not ? A small boat is almost the same work as something bigger. I realize smaller boats have been built, but sticking to the ~4mm plate is a good idea. Displacement will be a driving factor.

    Cheers,
    mark
     
  13. Barry
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    Barry Senior Member

    When you get down to thinner sheet gauges, the biggest issue that you will have is distortion caused by the heat applied during welding
    The type of weld joint can easily dictate what you can "practically" well steel, if you factor out distortion.

    So on a butt weld, without backing, 14 gauge, which is 5/64 inch, 1.98 mm would be difficult to do but with patience, ie short weld beads, 1/16 rod with a fast freeze puddle, it can be done.
    Backing on 14 gauge could take the form of say a 1/8th inch to 3/16 inch solid round bar held into the back of the joint, butt weld or fillet in the area of the chine where the fillet is not 90 degrees of angle, ie not 90 and not a butt weld.
    Remember that you will be welding both sides so the first weld on say the outside will provide a backing for the inside weld.

    The same 14 gauge, in a 90 degree fillet, is a bit better but the meeting of the joints has to be considered. In thicker material, say above 1/8th of an inch, you can join the say inside point to inside point and there is enough of a heat sink to allow the bead to solidify without blowing through. At the 14 gauge level, you would want to lap one side of the plate over so to speak so that
    you have a little backing to prevent blow through.

    Your best bet is of course to rent a mig welder and welding 14 guage is pretty easy. Tig might be better but more heat into the metal will increase distortion of the sheet.
     
  14. alanrockwood
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    alanrockwood Senior Member

    Thanks for the excellent replies.
     

  15. alanrockwood
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    alanrockwood Senior Member

    Regarding the 1/8th inch to 3/16 inch solid round bar bar, would it be acting as a non-fusable backing, i.e. not welded to the back side of the weld?
     
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