route manager

[rslotpole]

Does route manager take into account currents when calculating ETA and is speed speed through water or speed over ground?

[boat_alexandra]

Where would it get current data? I'm 99% certain it's speed over ground, so no currents.

[wdkester]

rslotpole, take a look at the weather router plugin

[PjotrC]

I also believe currently the ETAs just result from plan speed and leg distance, but indeed it is only natural to expect an extension here, taking into account sea current and wind predictions.

I have a custom version doing that, taking the data from gribs as handled by grib plugin.

As the example shows, a column is added to route waypoint properties, showing three values:

- the sea current prediction, as interpolated directly from grib
- the current vector projected on the route leg, i.e. net effect on speed along the planned route
- the effective drift angle, again computed for planned speed and course

The net effect of speed can be included in calculation of the next ETA or not, depending on a tickbox selection.

The idea is to show the general effect of current. It is not a perfect model for many reasons, starting with the doubt expressed by some scientists about whether point values of sea currents should be interpolated at all...

I have not used this (the sea currents part) a lot in practice, because it is not easy to find a source for combined wind/current grib. The only source I know publishes Norwegian forecasts for the North Sea and the Channel, but these files are very large... Nowadays there are convenient sources of sea current gribs, but to combine them with wind to produce a single file is too much work (for me)...

On the other hand, the wind part is always useful and nice, but I mentioned this already...

[rslotpole]

Thanks for your reply I'm still learning the ins and outs of opncpn and the plugins are a little beyond me for now.