any clear picture of sheer?

Discussion in 'Boat Design' started by isslam akkilah, Nov 29, 2020.

  1. isslam akkilah
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    isslam akkilah CrazyWarrier

    Hello folks
    I am trying to get what sheer is, so please can you post me a clear picture to a sheer and if you point at it, it would be great please.
     
  2. jehardiman
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    jehardiman Senior Member

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  3. BlueBell
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    BlueBell "Whatever..."

    I trust you didn't mean "shear".
     
  4. isslam akkilah
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    isslam akkilah CrazyWarrier

    sorry for disturbing, but the more sheer is high the better it is for skateboard? (is that right statement)
    also what type of lines shapes is this, and what are the different types look like (S-shape, reverce, ...etc)?
    at the end, what are the differences between strakes and planking?
     
    Last edited: Nov 29, 2020
  5. jehardiman
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    jehardiman Senior Member

    Ok....way too many different topics here. For what it is worth, the rise at the ends of a skateboard I believe is called "kick". I would need to make some enquires to my 40 year old friends to ensure this, as I haven't made or ridden a board since the early 1970's when we rode the classic flat short board styles.
    Sheer, and camber, are put into the weather deck to clear the deck of water. If the deck was dead flat, water would collect and reduce stability. The "sheer" is the longitudinal line the deck edge makes along the hull side. Camber is the "crown" the deck has between the edges and the centerline. Both help the deck shed water.
    The actual side profile is made by the bulwark. This is the structure above the deck edge designed to keep people on the vessel. In some cases there is no bulwark, or just a toerail.
    Originally (circa 1500), strakes (or whales) were thicker than average planks that ran the full length of the hull to reinforce the frames. Historically, ships were measured and developed from the frame face outwards, so a thicker strake/whale sat proud of the planking. Today, planks only exist in wooden hulls and there are still "whales" which generally carry loads, such a chainplates or "gun whales", into the structure. In "modern" (i.e late 19th century onward) steel and iron construction, a longitudinal row of plates in the shell was called a "strake" to simplify construction planning. The upper most strake of the hull (not bulwarks) that took the deck edge was called the "sheer strake". The sheer strake is thicker and contains a crack arrester because it is a major structural piece due to it's location.
    As far a sheer "shapes", there is infinite variety each designed to provide a pleasing shape to the eye and work with the bulwarks, toerails, and lifelines to keep people on the deck and water off.
     
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  6. Mr Efficiency
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    Mr Efficiency Senior Member

    Strange question, but most people would interpret the sheer line as being the profile formed by the upper extremity of the side of a boat. But, it may be technically incorrect.
     
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  7. jehardiman
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    jehardiman Senior Member

    For boats with no bulwarks, this is correct. But not exact, as in ships, the sheerstrake governs.
     
  8. isslam akkilah
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    isslam akkilah CrazyWarrier

     
  9. gonzo
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    gonzo Senior Member

    What do you mean by "skateboard"?
     
  10. isslam akkilah
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    isslam akkilah CrazyWarrier

    no just forget it, it was wrong I meant by that the shape of the skateboard
    example how skateboard looks like, but it is not.
    it is a piece of wood placed on the edges outside or inner
     
  11. gonzo
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    gonzo Senior Member


  12. Will Gilmore
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    Will Gilmore Senior Member

    Jahardiman's post is excellent. I'm learning lots from all of this. I would like to add to this last bit. For modern high speed powerboats, especially, a reverse sheer is often desirable to provide increased visibility when transitioning from displacement to planing speeds. Dropping the bow can keep the waterway in view when the boat's trim pitches up over the bow wave. Looks and dryness are not the only reason to play with sheer. Working boats will exaggerate sheer to make nets easier to haul aboard, or they will drop the transom. Use is an important consideration to shape for a boat.

    -Will (Dragonfly)
     
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