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    Re: Dip uncertainty
    From: Trevor Kenchington
    Date: 2004 Dec 7, 00:48 -0400

    You wrote:
    > On Dec 6, 2004, at 9:16 AM, Trevor J. Kenchington wrote:
    >> With anything of a sea running, of course, the uncertainties in the
    >> horizon and in the true height of eye that are produced by wave action
    >> are likely to overwhelm anomalies in dip for an observer close to the
    >> sea surface (except perhaps under the most extreme conditions).
    > Bruce Bauer had exactly the opposite take on this.
    Can you provide a page reference? I have re-read his section on
    rough-weather techniques and I can't find that he mentioned height of
    eye. Or do you mean his comment that a navigator on a ship's bridge
    should allow for wave height when applying the dip correction whereas a
    yachtsman should not?
    The latter is true, so far as I can tell, but I'm confidant that the
    allowance can be more precise than the yachtsman's attempt to guess how
    high his eye was, at the instant of contact between Sun's lower limb and
      the wave crest on the horizon, particularly since the rate of change
    in the dip correction falls off very markedly as height of eye increases
    (such that it is less necessary for the big-ship navigator to know his
    exact height of eye).
    Trevor Kenchington
    Trevor J. Kenchington PhD                         Gadus@iStar.ca
    Gadus Associates,                                 Office(902) 889-9250
    R.R.#1, Musquodoboit Harbour,                     Fax   (902) 889-9251
    Nova Scotia  B0J 2L0, CANADA                      Home  (902) 889-3555
                         Science Serving the Fisheries

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