helm visibility

Discussion in 'Boat Design' started by Armada01, Mar 6, 2018.

  1. Armada01
    Joined: Jan 2010
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    Location: Euroe

    Armada01 Junior Member


    According to ISO 11591 (Small craft, engine-driven - Field of vision from helm position. (2011)), visibility is - among other factors- based on standing and seated eye heights (high and low) relative to "a surface on which the helmsman stands" / or sits).

    There' a figure that comes with these definitions, where the high and low eye position are drawn with a measurement to a single horizontal line (eg the floor), giving the impression that both high and low eye positions are referenced to that same line.

    My question is whether this horizontal line needs to be fixed (one single reference line), with the high en low eye positions being two different heights relative to this line, or (what I'm looking for), the opposite: a single fixed high / low eye position with a varying floor height. This means that a person, tall or small, would set his stature height and his eyes would end up in the high eye position due to an automatically raising floor panel. Also, while the yacht would transition from zero speed to plane (with a resulting hump in between) the floor panel could adjust its height to maintain the high eye position (which would always be higher than the lowest unobstructed line of vision).

    I believe that one would end up with a more ergonomic set-up for the helm.

    Whether this set-up is allowed, brings us back to the definition itself of the eye positions, and more specifically, on what rationale the high and low positions were created: Were they created (high and low) to represent tall and small people, or were they created for a
    (average stature) person, with a varying vertical head position (like, maybe going through rough waves?)

    In the first case, a varying floor level would
    in theory
    have no conflict with the ISO guidelines , while in the second case, it would.

    Anyone have any deeper knowledge on this?
  2. Barry
    Joined: Mar 2002
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    Barry Senior Member

    proper helm seat placement

    copy this and paste it into the search box in the upper right hand corner

    these are the measurements for ABCY in North America

    You will see that a target has to be in place as well so the height above the floor and visibility to a target defines what you can see. Also horizontal field of view

    The idea is obviously short or tall, from these heights at max trim angle you can see something particular
  3. Armada01
    Joined: Jan 2010
    Posts: 32
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    Location: Euroe

    Armada01 Junior Member

    Thanks Barry for your input. Although I had read the post about proper helm seat placement before posting my topic. The requirements of the ABYC are pretty similar to those of ISO (I believe they collaborated to establish the ISO standards).
    However, I'm not looking for the rules, but rather how to interpret them.

    Anyway, I've adjusted the design to follow the guidelines as they were drawn in the figure (as referred to in the initial post), as it covers alo the written definitions whereas that's not necessary the case the other way around. Better safe than sorry....
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