built in "shape"

Discussion in 'English Only' started by cetigne, Mar 25, 2012.

  1. cetigne Member

    Hello everybody,

    I don't understand the meaning of this sentence: In order to create optimum efficiency, sails are fabricated with their "shape" built in".
    from the book Sol Power, by S. and St. Behling.

    Here is the entire paragraph actually:

    Form generation, not design, is the name of the game. Computer programs have been developed to simulate the stress of the wind on every cm2 of a sail. In order to create optimum efficiency, sails are fabricated with their "shape" built in. Scientists and engineers are constantly experimenting with new materials, construction methods, and shapes. The race to build the highest-performance boat and sails is as hard as the actual regatta itself.

    Does it mean that their shape is innate to them? That they couldn't look like something else, but just like that?

    Thank you!
  2. morzh

    morzh Banned

    I suspect that this is like so:

    Regular sails were made from pieces of material cut to shape and sewn together. The stress (tension) created by wind is irregular and depends on how the grain of material goes (fibers directions, seams, etc etc).
    This results in some stresses exceeding the material stretching ability, which leads to rips / tears.

    If one can build the shape into the fabric itself, it would result in more uniform tension across the area of the sail, and less tears during the sail's lifetime.

    The sailmakers of old tried to approximate that technique bu cutting material into smaller pieces and sewing them together. If one keeps making pieces smaller and smaller, it eventually results in exactly that - the structure itself becoming the minute copy of the sail's shape.
  3. Egmont Senior Member

    Massachusetts, U.S.
    English - U.S.
    It may not be obvious when we look at the average sailboat out for a pleasure cruise on a summer afternoon, but the exact shape of a racing sail is quite important. In fact, it is as important as the shape of an airplane wing - which it resembles in terms of how it works. The shapes of the pieces of fabric that are stitched together, the way the stitching is done, and the way battens (thin strips of wood inserted into pockets in the sails) are used combine to give the sail a certain shape.

    Since sails are made of fabric, they don't always have this shape. You can lower a sail, take it off the boat and stuff it into a bag, or roll it up into a tight cylinder - so the concept of a sail having a fixed shape isn't as natural as is the concept of an airplane wing having a fixed shape. Still, when the sail is hoisted and the wind blows on it, if it is properly made, it will take the same shape every time. For example, one sail might be flat and another one might be more curved.
  4. cetigne Member

    I guess I understood well, the shape is predestined... All those parts of a sail that have their specific purpose which generates their shape(s), hoisted or lowered, beautiful.

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