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Author Topic: Tidal modelling  (Read 14515 times)

November 12, 2017, 10:40:49 AM
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Having read the documentation, I understand how the tides ini file can model the height of tide at any given time.   Is there some way, however of modelling the tidal stream , the set and rate of a tide (direction it flows in and the speed that it flows) ?  I was thinking about something like this ...........

if a rising tide sets (flows in at a "heading") of 100 degrees and flows out at 280 degrees
tidal_axis = 100 {the heading of a rising tide}
max_rate = 4  {the maximum speed of a tide}

so speed of a tide at any given time  max_rate * sin (offset + tidal period)
the -ve speed then pertaining to a tidal stream in the opposite direction when ebbing (i.e. 280)

is there an existing way of modelling this ?

November 14, 2017, 07:41:24 AM
Reply #1
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I'm actually just in the process of implementing this for version 5.1.

The approach is to define the tidal stream speed and direction for each hour, from 6 hours before to 6 hours after high tide. This is done for springs and neaps (with the mean range of springs and mean range of neaps being defined as well).

Bridge Command will interpolate depending on the current tidal range, and the time relative to the nearest high tide. This should match the 'Tidal diamond' approach used on UK charts. You will be able to define the tidal stream in as many locations as required, with and Bridge Command will interpolate between them.

I've implemented this already, but need to complete thorough testing.