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Ocean
Clocks Tides of Puget Sound - West Coast Tide Clock Details
Windward
Instruments has received questions regarding the accuracy and viability
of our Ocean Clocks Tides of Puget Sound tide clock. Some customers
have been told by other dealers that this clock does not work, because
there is no such thing as a West coast U. S. tide clock.
This
is a false statement.
While most of
the West coast of the U. S. does not provide a predictable tidal flow,
the Puget Sound, WA. does, as people who live there will attest. To
solve the confusion, we will explain in factual detail below, how and
why the Tides of Puget Sound does work.
The Puget
Sound is a huge mass of water, mainly land locked, creating a virtual
basin of it's own. It does have some reasonably consistant tidal
movements, but not as easy to predict as the East Coast. Therefore the
accuracy stated has a much wider tolerance range than for the East
coast models.
To determine
dial placement for prediction by port (for the Puget Sound and every
Ocean Clocks model) the tide times for an entire year for the major
ports are entered onto a spreadsheet. These times are then subtracted
from each other and averaged over the whole year. This arrives at a
figure that can be used as an approximate time difference between the
major ports, with the minor ports time differences being subtracted or
added to these times.
Over the
whole year this provides fair accuracy, however, there is a tolerance
drift from the actual tide time which can be as much as +/- 90 minutes
for the Puget Sound area. Setting the clock the day after a new or full
moon places the clock in the middle of the tolerance range, providing
equal oscillations of +/-90 mins. The tolerance band ranges so that
every 14 days it is in the Positive and the next 14 days it is in the
negative (28 day lunar cycle). If the oscillation is not equal you can
get a difference of 3 hours which is not that good.
For
West coast regions outside of Puget Sound, the tide times can not be
predicted by a regular clock, as there are too many anomilies which
counteract any clock timings. Land masses, under sea basins, and the
sun's gravity, collectively added to the moon's gravity, all influence
the tides. This is why tidal prediction by way of analog device in
other West coast areas isn't possible.
All
analog tide clocks regardless of make or model should be considered to
indicate the approximate condition of the tide - not to accurately
guage the tide. Many digital tidal prediction instruments and software
only provide +/- 15-30 minute accuracy.
Windward
Instruments recommends the use of NOAA or SGPS provided charts or
information, if you require accuracy for pilotage of a vessel, or
similar activity.
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