Newbie,steel grades and standard thickness ?

Discussion in 'Metal Boat Building' started by philgib, Nov 12, 2008.

  1. philgib
    Joined: Nov 2008
    Posts: 20
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    Location: MEXICO

    philgib Junior Member

    I am such a newbie in this forum that when I ask a question, another one arises immediately.

    Like, I am asking for the price of a 6mm steel and of course someone asks me for the grade I need... So I am starting a new thread for the next newbies. I hope you don't mind otherwise whip me and I won't do it again ;)

    1- Is 316 the only grade I should care for, for an 18 feet steel barge, simply because it has more resistance to corrosion ?

    2- Then what thickness should I use for
    - Deck plate ?
    - Bottom plate: ?
    - Side shell plate: ?
    - Keel plate: ?

    Bottom plate and keel plate will be the same I guess, and will receive a 13 cm layer of cement to make it a 5 tons keel. Should I need extra stiffness and thickness for that reason ?

    From most previous posts I am reading it looks like 6mm is common, but for which part of the barge ?

    I don't mind paying a bit extra and having it heavier if it makes it really solid.

    If you know of any good internet site so that I can educate myself, that would be just great. Wikipedia is a bit short on it.
  2. MikeJohns
    Joined: Aug 2004
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    Location: Australia

    MikeJohns Senior Member

    I'm afraid you really need to start with some basics and some homework, your questions are so general as to require some long and involved tuition.

    From the internet download some of the free scantling rules and read them for a start. Then get hold of some books on steel construction and read them.

    We never use stainless steel(eg 316) except as a liner, hulls are just plain mild steel usually with around 300MPa yield.

    Thicknss and framing are either specifically calculated or dictated by the scantling rule and the numbers you feed into the rules such as length depth loaded displacment.

    Global strength is important for longer barges where you analyze the total hull girder strength.

    But if you ask such basic questions it begs the question what are you doing?

  3. marshmat
    Joined: Apr 2005
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    Location: Ontario

    marshmat Senior Member

    Hi philgb,

    Probably the next thing you should do at this point is to go to your local bookstore (or ) and get a copy of Dave Gerr's "Elements of Boat Strength". It's $25 well spent. Chapters 1 and 13 through 17 contain the answers to all of the questions in your first post, and most of the questions that you'll have once you answer them, except for the current price of steel.

    That price changes wildly by the month, and the only reliable way to get a price for estimating purposes is to work through the scantling calculations, figure out just how much of what steel you need, and ask a few local suppliers to quote the lot.
  4. Landlubber
    Joined: Jun 2007
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    Landlubber Senior Member


    from your other posts you are making a barge, but it is only 18 feet long. there are design rules for masrine vessels in survey, meaning the boats will be used for commercial purposes.

    are your boats going to be used commercially or do you just wish to make a small barge

  5. Brent Swain
    Joined: Mar 2002
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    Location: British Columbia

    Brent Swain Member

    Regular mild steel is all you need.A36
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