Yacht General Arrangement

Discussion in 'Boat Design' started by monrosm@shrewsb, Mar 28, 2014.

  1. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    Probably a bit like First Angle and Third Angle projections. Both valid (at least a few years back) but fortunately 3rd Angle has preference, well I find it easier!. Ironically I think one of the last 1st Angle drawings I dealt with was US in origin.
    Normal engineering drawings (in UK) are to ISO/BS 8888 (previously BS308) where 3rd Angle is given preference. The key thing is clarity in the drawings so that they can be read and interpreted correctly.

    Trying to get universal CAD standards is a whole different ball game. Regrettably a somewhat political one as different vendors/developers vie for position. Harder still when some won't release the format, for translators. Fortunately there are at least 3 accepted electronic transfer formats. So trying to get a universal Zero point with Cartesian coordinates in 3D is some way off!.
    Like paper, as long as the 'drawing' (model) is clear, that is the main object.

    Of course the marine industry tends to draw the bow to the right (post Chapman) but the aircraft industry tends to be the other way, nose to the left. Each discipline which requires drawings seems to have developed its own conventions to describe the necessary information for interpretation by those involved in their fabrication.
  2. DCockey
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    DCockey Senior Member

    Standard in the auto industry, at least the part I worked in, is for the front of the vehicle to be on the left.

    For vehicle packaging, engineering design, etc we always used X increasing rearward, Y increasing to the left facing forward (port in nautical terminology), and Z increasing upward, which results in a "left hand" system.

    The SAE standard for dynamics had Z positive down so that the resulting coordinate system was "right handed".
    Last edited: Mar 29, 2014
  3. DCockey
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    DCockey Senior Member

    When starting the engineering design of a car or truck one of the first decisions is where to locate the coordinate system origin. If the design is based on an existing design then usually the coordinate system of the predecessor design is retained to simplify re-use of the design. For a "clean sheet of paper" design a choice has to be made. On the vehicles I worked on we decided to put the origin far enough ahead of and below the vehicle that X and Z would always be positive, including for potential follow-on vehicles. This eliminates the need to keep track of the sign of X and Z coordinates. Given the mostly symmetric nature of road vehicles the logical origin for Y is on the vehicle centerline.
  4. Squidly-Diddly
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    Squidly-Diddly Senior Member

    When laying out studs, joists and rafters on a house you are SUPPOSED to start from one of the four corners(I can't remember which, but I'm guessing it is SE so you will be in 'positive/positive' quadrant of 360'), so if the house is properly laid out, you SHOULD be able to determine the exact location of framing members inside the walls (before they had those 'sonar stud finders', and before 'the trades' generally went to crap) w/out knocking holes in the walls or relying on magnetic sig of nails.

    When I starting drawing ships as a kid I think it was easier to start the bow facing right as a right hand drawer.

    Now when I draw boats I start with 'the hold' or what I'd like the boat to carry, then add bow and stern and it is more awkward.

  5. Jure29
    Joined: Sep 2017
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    Jure29 Junior Member

    It's cause somebody made a rule that the boat is drawn from stern to bow, and in all drawings you can se that the view is from centre line to PS for longitudinals, frames from stern, and decks from above for structure. Other departments draw decks and structure above like in GA, only the hull structure is drawn with deck and bulkheads below. It's technical drawing standards.
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