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Old 21-06-2012, 08:45   #1
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Tidal Current Plugin For European Waters

Not quite ready for publishing this one yet but ....

C++ help is needed!

I am using the great work done by SethDart to display KMZ files on OpenCPN. Using the plugin it will be possible to select a georeferenced OpenCPN display of tidal currents for, say, the English Channel, for a particular time.

High Water Dover times are needed bu I have not found a plugin interface to this data. Will I need to program this as part of the plugin or is there another way forward, using OpenCPN?

Ideas are welcomed.

Mike
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Old 21-06-2012, 23:35   #2
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re: Tidal Current Plugin For European Waters

Hey Mike,

This is certainly an interesting idea - there's actually a really cool website called tidetech.org that provide tidal stream data in grib format - so if you were able to write some kind of plugin that converted the data to grib, we could use the existing grib plugin to actually display the data.

Food for thought...

Keith
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Old 22-06-2012, 02:24   #3
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re: Tidal Current Plugin For European Waters

It's already available.
Click image for larger version

Name:	grib-tide.png
Views:	333
Size:	375.0 KB
ID:	42619

It's not on the screen-dump, but the current velocity is displayed for the position of the cursor.

3 days predictions, for every whole hour, available from ftp://ftp.bsh.de.

Areas from the Wester Approaches to the Baltic.

Thomas
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Old 22-06-2012, 03:17   #4
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re: Tidal Current Plugin For European Waters

Keith/Thomas

Thanks for the input.

Both of these solutions don't really address the needs of someone who usually uses a Tidal Stream (Current) Atlas for a passage from say Salcombe, Devon, UK to Guernsey. What is the tidal current in the Little Russel, between Guernsey and Herm, for instance. I can't zoom the Grib in close enough.

For this level of detail we need tidal diamond information from the paper chart (access to the harmonics would be nice!) or the Tidal Atlas, both of which can use HW Dover as the reference port. Or, you can purchase another program, but there will often be an expiry date on the information.

A sample of the output from the primitive tidal current plugin is attached. There are issues about UKHO copyright (the Tidal Stream Atlas I use was purchased!) and I think any tidal current data files would have to be encrypted and sold under license.

Mike
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Old 22-06-2012, 03:42   #5
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re: Tidal Current Plugin For European Waters

currents & tidal files for the most part of Europe may be downloaded here

https://docs.google.com/file/d/0BzWFudy66pnENmE2YWE3YmUtOThlNy00MWIyLWJkYmItNjZlY jhlMmM1MDdm/edit?pli=1

paste the files in TCData folder, delete the older ones (save them for a further use)
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Old 22-06-2012, 04:16   #6
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re: Tidal Current Plugin For European Waters

this one is newer (Harmonic V8 for European waters)
https://docs.google.com/open?id=0BzW...GUzaG9JakxRbEU
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Old 22-06-2012, 14:40   #7
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re: Tidal Current Plugin For European Waters

Quote:
Originally Posted by yantho View Post
this one is newer (Harmonic V8 for European waters)
https://docs.google.com/open?id=0BzW...GUzaG9JakxRbEU
Interesting that the Tidal Current harmonics (and the USA ones as well) give rectilinear results. The tide flows one way or the other, about 180 degrees difference in direction.

Certainly the Tidal Currents around the Channel Islands (Europe) have rotary vectors, which are shown on the Tidal Atlases.

Mike
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Old 22-06-2012, 16:23   #8
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re: Tidal Current Plugin For European Waters

Quote:
Originally Posted by Rasbats View Post
Interesting that the Tidal Current harmonics (and the USA ones as well) give rectilinear results. The tide flows one way or the other, about 180 degrees difference in direction.

Certainly the Tidal Currents around the Channel Islands (Europe) have rotary vectors, which are shown on the Tidal Atlases.

Mike
I agree. OpenCPN needs a current dialog that can display the general case with rotary currents. The present dialog is only a good approximation in very restricted waters.

Thomas
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Old 23-08-2012, 03:32   #9
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re: Tidal Current Plugin For European Waters

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Originally Posted by cagney View Post
I agree. OpenCPN needs a current dialog that can display the general case with rotary currents. The present dialog is only a good approximation in very restricted waters.

Thomas
This would indeed be very handy. Whilst moving the time scale, see the effect on the tide and current direction.

George
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