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forrestguice / SuntimesWidget

Android app (and widget collection) that displays sunlight and moonlight times.
GNU General Public License v3.0
338 stars 61 forks source link

Support for tide tables #379

Open Philippe-Arnaud opened 4 years ago

Philippe-Arnaud commented 4 years ago

Hello,

I'm very fond of your app and, since tide is closely related to the moon and sun position, I wondered whether you considered supporting tide reports in you app?

Cheers, PAH

forrestguice commented 4 years ago

I've thought about this. Using the app to better understand the tide is a usecase I want to support, but I think actually making tidal predictions is out-of-scope.

I was curious about how to go about making predictions though and stumbled on https://www.tidesandcurrents.noaa.gov/faq4.html#60 (and also https://stackoverflow.com/questions/14698104/how-to-predict-tides-using-harmonic-constants).

It seems that geography plays a huge part in this. To use these algorithms you need "harmonic constants" that are periodically (re)calculated and published for individual stations. Its very location specific (and not something I think Suntimes can easily support).

I think a separate tide tables app (maybe an addon similar to SuntimesCalendars) makes more sense. It might focus on a single location, or a list of pre-defined stations, or ui for providing constants. The sun and moon position (and other info) can be obtained from Suntimes through its content provider.

nognkantoor commented 4 years ago

xtide https://flaterco.com/xtide/ GNU GPL 3 or higher. would probably make a good starting point for a tide table supplement for SunTimes.

xandro0777 commented 3 years ago

Libxtide has been in fact compiled on Android. Harmonics data availability is a problem however.. not much outside US

xandro0777 commented 8 months ago

BTW there were .. long before smartphones not to mention smartwatches.. wristwatches with "tide prediction". Iirc Casio. Did anyone test any of those? Whatever they did for $30 in the 1990ies should be easilly doable.

The question would it be worth the effort?