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    Re: Tides by bearing of the moon
    From: George Huxtable
    Date: 2009 Apr 7, 18:11 +0100

    Hewitt wrote-
    | Living here in the US Virgin Islands I've dabbled at it, but the tides
    | here are not diurnal as they are on the US East Coast but more like
    | what I've heard of the tides around England.
    Those words puzzle me. I have a book here by a American named Marmer, from
    1926, "The Tide". Which shows some predictions for Sandy Hook and New York
    harbour. And those tides appear to be very semidiurnal (repeating after 12
    hours or so), without much daily inequality, between am and pm tide. Those
    are just like the tide pattern we have here in UK waters.
    Is the pattern very different elsewhere on the US East Coast?
    Hewitt added, about tables of luni-tidal intervals-
    "In comparing this lunar method with the published tables, I noted that
    there were often noticeable differences between what the table would
    say and what I actually observed on the water. I figured this was
    because the tables are generated by a computer which could not know
    what the wind or barometer were going to be on the predicted day and
    time. Both wind and barometric pressure affect the tide."
    That's certainly true, that weather can affect tide, but it most cases it
    calls for rather extreme conditions to have an important effect. Predictions
    of luni-tidal intervals are averaged over a wide range of conditions (most
    important, phases), and for that reason do not predict tides well on a
    particular day.
    contact George Huxtable, at  george@hux.me.uk
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
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