One Piece Aluminum Hull with Chines?

Discussion in 'Software' started by trw2018, Jul 24, 2018.

  1. trw2018
    Joined: Jul 2018
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    trw2018 New Member

    I have a scenario that I think is fairly uncommon, I've done a lot of google searching and can't find a way to do what I want to do, because apparently the way I'm building the boat is not super common.

    Essentially, I'm building an aluminum boat. It starts off as a 20 foot long * 8 feet wide sheet of aluminum, and is bent into a "U" shape on a press brake. At the bow of the boat, it's just a flat, straight bottom, with the 2 sides of the boat (flat). 2 bends. However, on the rear, there are chines that taper to nothing by the time they get to the rake of the boat (6-8 bends).

    To form the rake, I cut a "V" up the front center of the hull, then cut 2 straight lines up the side a few feet, which separates the bottom of the boat from the center. Then, I pull the 2 halves of the bottom together until there is no longer any empty space between them and then weld together. This forms the v rake of the hull. Then, I pull the sides in until they meet the bottom.

    My issue comes from getting this into CAD. I assume I will need to surface model this, but I'm running into issues caused by having chines broken into the sides of the boat. I can find 10000 resources on how to make a simple hull out of flat pieces that are then curved, but nothing concerning forming pieces that are already bent.

    My current CAD program is Inventor, but I have experience in Solidworks and I wouldn't mind switching to another program to make the hull and then export it back to Inventor.

    Anyone have any suggestions for a program that can do what I'm looking at? Rhino?
     
  2. DCockey
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    DCockey Senior Member

    Can you provide an illustration of the shape of the aluminum sheet before it is bent into the boat shape, and also an illustration of the shape of the finished boat?
     
  3. trw2018
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    trw2018 New Member

    [​IMG]


    This boat in particular might not be a 1 piece hull, and it's a v bottom, not a flat bottom... but the way the rake is formed looks to be the same, and there are chines in the side of the boat.
     
  4. DCockey
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    DCockey Senior Member

    Quick example of folded boat shape and the "unrolled" surface done in Rhino as a response for this thread.

    Folded Boat DC01.JPG
     
  5. trw2018
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    trw2018 New Member

    Yep, that's pretty much exactly what I'm referring to. But what I'm not sure about is can Rhino curve a surface that's bent?
     
  6. DCockey
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    DCockey Senior Member

    Rhino can unroll a curved or folded surface provided it's close enough to developable. Proceedure in Rhino (or software with equivalent capabilities) is to design the shape in 3D, the unroll to 2D.

    When you talk about "chines" do you mean the intersection of the sides and bottom, or do you mean flat strips between the sides and bottom which are sometimes called "chine flats"?
     
  7. trw2018
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    trw2018 New Member

    I'm referring to the flat strips between the sides and bottom.

    That's also part of my issue, I don't know how I could make a 3d model that's accurate to the process I'm currently using. Since I'm basically trying to reverse engineer my current process.
     
  8. Barry
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    Barry Senior Member

    The pieces that you are referring to between the sides and the bottom, are normally called lift strakes.
    For a slight V hull, they aid in directional stability if properly formed, they also stiffen the flat bottom plate and provide additional lift.

    While you would be able to form the strakes into the bottom plate, parallel to the keel, you will not get a sharp transition, (to limit the Coanda effect) and when they are formed they
    will give a stiffness to the plate that will make it difficult to bend up toward the bow, ie put a curve into it.

    Normally, on thin sheet aluminum boats, they are riveted in, (and often provide stiffness to the bottom and directional stability but little in the way of lift due to their shape)
    On heavier aluminum boats, say 1/8 inch and up, they are welded to the bottom plate usually after all the interior stringers are welded in place.

    Normally, lift strakes are installed in the flat portion of a boat when building in aluminum and run about 2/3rds of the way up from the transom to the bow
     
  9. ludesign
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    ludesign Senior Member

    Building out of one sheet is actually fairly common in one way or another. Done it myself since the seventies. Many programs can unroll plates, though the abilities vary quite a lot, so it may pay off to check it out how they fair in detail. I personally use TouchCAD, as optimizing the unwrapping is an integrated part of the hull fairing.
     

  10. DCockey
    Joined: Oct 2009
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    DCockey Senior Member

    Can you provide some photos of pieces which have been formed after being bent. Photos before forming would also be helpful.
     
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