GRIB data and presentation
A GRIB file (GRIdded Binary) contains a wind or current forecast for regular points over an area, at a number of future time instances. The information is stored according to the most common grib 1 format or to the newer grib 2 format. A lot of different techniques are used to compress the files to reduce size without loosing resolution or accuracy.
Seapilot automatically detects whether a file contains wind or current data. When the file has been opened in Seapilot you can visually follow the changes of the wind arrows using a time scale corresponding to the period of the forecast. It is also ready to be be used for finding optimal routes.
A general GRIB file type for global use is GFS (Global Forecast System), offered by American National Weather Service, NWS. In Seapilot you access the GRIB menu via Settings ->GRIB. You may, without needing to give the url, choose files from GFS with different forecast intervals (12, 48 or 168 hours). The file will cover the area which is currently shown on the Seapilot screen.
Specific GRIB files may also be downloaded for free or ordered from several weather services. If you have downloaded (or emailed from a computer) a GRIB file to your Seapilot unit, you tap to open it and choose Seapilot as the goal for the import. This way to import a GRIB file is suitable for a single use, however ”Update” does not work since Seapilot don’t know where to fetch updated information. Such a GRIB file must be downloaded and imported each time you need it.
The best way to always have access to updated GRIB files is to state the specifik URL (see below). You only need to do this once.
Examples of GRIB files in high resolution for Gotland region and Swedish Westcoast, produced by Swedish SMHI (uppdated at 03, 09, 15 and 21 UTC):
- Go to Settings ->GRIB, and then tap “+” to add a GRIB.
- Choose “URL” and state the address (copy and paste it into Seapilot):
- http://static2.weatherpal.se/files/maps/grib/Gotland.grb (case sensitive)
- http://static2.weatherpal.se/files/maps/grib/Westcoast.grb (case sensitive)
To update the GRIB file you tap the “i” after the name in the GRIB menu and then tap Update.
GRIB files for (among others) Northern Europe (and current forecasts for Skagerrak) are available from Norwegian yr.no.
GMN Marine Weather Service offers world wide ”FREE GRIB Files”.
All above url-s are subject to changes.