On 2019-02-19 11:11, Tony Shield wrote:
> Depth of water in tidal areas can vary enormously. People using depth for
> navigation and general use would expect to use depth at MLWS (Mean Low Water
> Springs) and add increments based on tide tables, I suggest that OSM does the
> same. Use the tidal tag and perhaps a tidal-range tag, in metres, tidal_range
> is the difference between MHWS (Mean High Water Springs) and MLWS.
>
> note - Spring tides are the highest and lowest forecast tides and are based
> on the relative position of the earth, moon and sun.
Indeed, they are astronomical predictions, but not forecasts. They are
not in themselves good enough for planning a (route to a) berth in a
harbour for example. There are many other factors influencing the actual
water level, like global/local weather conditions and seiche waves.
Depth is of course also affected by dredging operations...
Should OSM aim to replicate the Admiralty Charts and tide tables?
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