Originally Posted by wizard-merlin
Thanks Pavel, no, I realise I can't get this data outside US. I note though that the Harmonics file is ASCII, and it should be possible (theoretically) to populate it with the data from my paper charts, if I could work out the structure. An alternative, which would give a nice visual display would be to create a GRIB file of tidal data, as you could jump through the time. This seems impossible, as GRIB creation seems solely UNIX based. So I'm back to understanding the Harmonics file to update it manually...
This has been done (i.e. currents) for France
by a friend of mine (Merak56 on french forum Hisse et oh !
You can download the file here (tides + currents) (replace the harmonic and harmonic.idx files in tcdata folder for testing)
Easy to back engineer
to suit (I've done it)
Brown spots on chart + an example
However the display may be rather oversized due to current
(no pun intended) limitations on OpenCpn
(up to now, at least)
Also on French charts and documents (at least) the data (velocity and direction) is given separately for neap and spring tides. I understand that a single
set of values is required in OpenCpn