On Monday, September 18, 2017 at 11:29:14 PM UTC-4, vk3anz wrote:
>
> Just a word of caution - there is more to the tide than just the location
> of the sun and moon. The local coastline and bathymetry play a bit part and
> can change times by some hours.
> When I worked for the local meteorological organisation, I found that it
> was not at all straight forward to provide general tide information. For a
> specific location it is possible to work out the various biases involved
> and this is how the published tide tables are done.
> Susan
>
right you are, susan! the forecast extension uses the 'xtide' program by
david flater:
http://www.flaterco.com/xtide/
xtide uses harmonic tables from known, measured sites to forecast the
tides. unfortunately these harmonic tables are not available for every
location.
if xtide does not have your location, it is possible to create a harmonics
table, but this requires about one year of tide measurements.
http://www.flaterco.com/xtide/harmonics.html
just to see how difficult this might be, i've been running a tide monitor
built from a maxbotix ultrasonic sensor connected to a raspberry pi,
running weewx. more about that in a month or two when the first year of
data are complete and sanitized...
m
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