Loftsman wanted.

Discussion in 'Boat Design' started by Alexanov, Mar 15, 2015.

  1. Alexanov
    Joined: Feb 2003
    Posts: 211
    Likes: 25, Points: 38, Legacy Rep: 10
    Location: Norway Sola

    Alexanov Senior Member

    About twenty years ago shipbuilding technology start migration into computers world. Now we are in 3D reality. No more paper drawings. 2D AutoCAD drawings are standard for us. Most of the design companies use 3D modelling systems. We use CNC programs for bending and cutting plates, bending profiles and pipes. Shipyards use welding robots and lot of other modern equipment. Bright future. It’s look like that from designer point of view.

    There is a lot of different software for initial design. Designers use special ship design packages and “universal” 3D modelling software. Mostly it’s depending from company size, software price level, and peoples in the company with 3D software experience.

    When project comes to production, the situation is little bit different. The are few heavy and expensive systems for workshop production documentation. They cover all modelling process from structure modelling to CNC cutting and bending files. Modern hull modelling systems can do almost everything. CNC cutting machines can cut any parts with the highest precision. But, I know, very often people for Yard complain about some construction documentation. Thees nerds from Yard can’t bend plate again, can’t weld stiffeners to shell, have big gap between shell plates and delay with delivery, because of waiting for decision from design office. How is it possible in our perfect computers world?

    When it’s happen my first question is - May I have a look at hull surface?

    Most of the CAD systems for production workshop documentation don’t have production lines fairing module. They just have a possibility to import surface and, may be, “fix” some problems. At same time there is a lot of fancy software for ship surface generation. We are mostly use it for initial design. Make your surface in few hours, good enough for initial drawings, may be for CFD and for nice presentation pictures what can be better? Shaded surface always look’s nice. But can we use it for production?

    Unfortunately, while we run into the bright future, we lost some important persons from our team. We lost persons who knew about ship surface everything. From time to time, on presentation of the new, modern, fancy software, I can heard from somewhere: “Is this surface good enough for production?” Than I know some of this people steel alive - it’s loftsmans.

    For long time loftsman was a one of the most important person in ship building. Now it’s so easy to make ship surface, so everybody can do it. Yes, a lot of processes in lofting, computers can do much better and faster, but lines quality, hull shape, is a task for human brain. Lines fairing even more complicated with computer, than manual - ask loftsman. Another bad news is lofted plate parts will follow all fairing problems exactly, but shell plates and profiles not. In case of bending we can’t cheat mother Nature. This is another dark side of the computers modelling.

    I work with hull lines more than 20 years and it will be interesting to know how this process organised in different companies. What software is used for production line fairing? How important it for Yard?

    Dictionary on my iMac don’t have LOFTSMAN word anymore. May be this is past?
     
  2. TANSL
    Joined: Sep 2011
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    Location: Spain

    TANSL Senior Member

    I'm not a loftman but I also really love the work of loftmen. I think that indeed was one of the most important jobs of a shipyard.
     
  3. micspoko
    Joined: Jul 2010
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    Location: Poland

    micspoko Senior Member

    When I start working in my shipyard (repair shipyard) I see a loftsman in work now of course we are using 3d software. In my career a lots of time I was a hull technologies during repairs or conversion of ship. But most interesting work was a repairs bows after collision of ships without original documentation (bulbous bow and upper parts of bow) and I know there will be always problem with bend the plate (with hard bending). And when I have a problem to see if will be possibilities to bend this plate I always use something like that - printing o paper in scale frames and others stringers to made a 3d model and printing a developed plate to see if will be possibilities to bend this place. Because if you smooth bend a sheet of paper you will able to bend a plate.
     
  4. Alexanov
    Joined: Feb 2003
    Posts: 211
    Likes: 25, Points: 38, Legacy Rep: 10
    Location: Norway Sola

    Alexanov Senior Member

    Everything looks so simple in 3D CAD world, shaded surface always perfect, lines nice, and presentation wonderful. There is kind of illusion of real life. Illusion of the competences. I am just afraid from year to year we lose some part of knowledge, how to work with ship’s surface, bend plates and etc. Not long time ago I have got IGES file with hull surface. Yard just ask to help with thruster surface modeling. When I look at the lines I found that lines is not faired at all! It was just nice surface for presentation. When I tell it to the yard, they answer - aftship already build and there is no reason to do any changes in foreship. It surprise me a lot. They promise send me a pictures after finishing with the hull
     
  5. TANSL
    Joined: Sep 2011
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    Location: Spain

    TANSL Senior Member

    A good loftman not need to make a template of the plate to see if it was or was not developable. There are enough approximate methods, there had methods, to develop not developable plates. But today, in fact, no good loftmen active.
    Rendering programs are prepared for the hull surface looks very smooth. They use algorithms for that and play with lights and materials. They can not even ensure that the surface pass exactly by molded lines. But as people do not know the trade, do not pay attention to those things.
    Since shipyards build very often with mold, the designer leaves it to the carpenter that smooth the mold. (I'm talking about small ships).
    People complain that this is a ruinous business but despise knowledge that could greatly increase productivity while reducing costs
     

  6. Alexanov
    Joined: Feb 2003
    Posts: 211
    Likes: 25, Points: 38, Legacy Rep: 10
    Location: Norway Sola

    Alexanov Senior Member

    Thanks TANSL. It's good to know that I am not only one with my opinion.
     
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