Getting the sea current from harmonics file

[BerndCirotzki]

Hi, I was working with your wonderful plugin. But I have a little problem.

when building a weather route, one of the most importent thing is the sea current. But when sailing, for example, in the english channel, the "climatoric plugin" is not working. But Opencpn knows the current by the "harmonics files" or useing plugin "otcurrent_pi". Would it be possible to integrate this into the plugin ?

or a second way also to open two grib files at same time. One with the wind data and the other with the current data. (this is usfull for saildocs gibdata, because ther is no Model that includes both at same time.)

... then, for the calculation it is able to set the max/min TRUE Windangle. would it be able to make it also possible to make the calculation with the "APP" Windangle ? ... for Examle the are 5kn current from "somewhere", the true Wind calculation would not be so good.

thanks for thinking about it. Bernd

[rgleason]

Bernd You can already load two grib one wind and one current. Please read the manual.

[BerndCirotzki]

@rgleason Hi Rick, you are right ... this I don't know. thanks for that ... so I tested it. and .... the current, when it comes from two files is shown correct in the grib plugin, but it is not fully or correct working in this plugin. see here : the black current arrows are missing since the middle of the track, but the current values are available. (could be an error in grib Plugin or in this plugin ... I don't know. )

..... And how it comes ... by testing it, I found an error in grib Plugin by painting the area in Multicanvas mode :-(

But hower ... the current is avalible in the "harmonics file" ... a grib file would than not be needed when taking the current from there in weather routing.

(OK, in this case the track is over the land. I have not included the drawing plugin in this test)

[seandepagnier]

I dont know about your experience with harmonic files, but they generally cover tidal streams correct?

In my experience these files are more of a general guide but the actual current could be a lot different. Maybe because this is often in rivers or other areas with tidal effects where wind and rain also plays a role, but also because a slight difference in location and the current is completely different.

I am also not sure how you would interpolate since the data is not a grid. So some sort of clever algorithm would be needed, but what is the point when the result would not be accurate anyway?

[BerndCirotzki]

I dont know about your experience with harmonic files, but they generally cover tidal streams correct?

Yes, they cover the tidal streams.

In my experience these files are more of a general guide but the actual current could be a lot different. Maybe because this is often in rivers or other areas with tidal effects where wind and rain also plays a role, but also because a slight difference in location and the current is completely different.

I think they work very correct. And it is realy much better to use them, in some sea areas, as not. I the english channel there is a current up to 10 kn. (google : alderney race)

I am also not sure how you would interpolate since the data is not a grid. So some sort of clever algorithm would be needed, but what is the point when the result would not be accurate anyway?

Yes, I also think it could be compliate, and I also don't know have it works. But there is the "otcurrent plugin" that uses the files or OpenCPN himself. So it would be able to see in this code and copy something from there.

I understand that you had an other concept with your Plugin. It was only an idea that I had. First I have had the Idea to develope it myself into your code, but it would take me a long time to understand your code.

But much thanks for your answer. We will see, it could be a project for next winter for me.