The weather router solver requires a wind GRIB file. The solver can not operate without wind forecast data. Wave height and current data is optional.
If you want the solver to use wave height or ocean current data, you must enable the appropriate setting.
All of the ocean current forecast models have shorter forecast durations than the longest of the wind forecasts. Enable this setting if you would like to use the ocean current data, even beyond the time the GRIB data indicates it is valid.
If you use the OSCAR current model, you must enable this option. OSCAR data is a rolling average over the previous five days. OSCAR data is always historic. However, some sailors have found this model to be more reliable than others, for some areas of the world (perhaps the more remote areas?)
The NCOM current models contain three or four days of forecasts data, so enabling this option will almost always be necessary when using these models.
If you are on passage and are downloading data through a slow connection, you may choose to download a large area of ocean data before leaving, and then use that data during your passage. In this case, you will need to enable this option.