Plate deduction for Steel hulls

Discussion in 'Metal Boat Building' started by robmill54, Oct 10, 2008.

  1. robmill54
    Joined: May 2006
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    Location: ft myers, fl

    robmill54 Junior Member

    The set of plans I have from the designer Mal Low, does not specify if the offsets are to the outside of the hull plating or not.
    Mal very unfortunately, has terminal cancer, and no longer accepts questions on his designs. (I want to respect his wishes not to be asked.)
    There usually are notations on the plans but not in this case.
    It makes a difference in displacement on wooden hulls to be sure to deduct plank thickness, but what about 10 gauge plate, do you guys bother to deduct plate thickness from the lofting?
    I'm about to start frame construction so I'm not sure about this.
  2. Crag Cay
    Joined: May 2006
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    Location: UK

    Crag Cay Senior Member

    I think you can assume with steel boats that the plans or offsets are to the inside of the plating.
  3. Arvy
    Joined: Jun 2005
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    Location: Netherlands

    Arvy Senior Member

    Plate deduction

    Hi Robmill54

    I don't know the Mal Low designs, but almost all the designs I have worked with (mostly vd Stadt, Jongert, Dijkstra and a lot more) all use the offset to be on the innerside of the plating. So plating goes outwards (all plating, including decks and superstructure). This is mostly done for easy construction because one hardly has to make corrections for thickness.

    You should be able to do this too with the Mal Low design when all hull plating is of the same thickness. When you don't have the same thickness all over the hull, you can see this as a little jump in the frames.

    In metric the thickness is only 3.4 mm (I am dutch, so had to translate the thickness to metric) so I don't think it will matter much wether you deduct the thickness or not (but to be sure, check the length of the frames to the width of the expanded plates).

    Hope this helps.

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