Copernicus tidal currents data is based on the variation of sea surface altimetry measured by satellites (From CMEMS Copernicus Marine Environment Monitoring Service).
https://resources.marine.copernicus.eu/?option=com_csw&view=details&product_id=SEALEVEL_GLO_PHY_L4_REP_OBSERVATIONS_008_047&pk_vid=6a7ee01823b6880d16118287836873d6
From this data which gives the sea surface level, tidal currents are computed.
The satellite data resolution is 0.25° x 0.25° or 15NM x 15NM (27km x 27km). That is enough to estimate correctly the sea surface level excepted in closed, long or narrow bays. In fact the tidal currents speed depends also on coast line and seabed mapping. So in some areas these currents are probably underestimated.

@afurley
All waves models don’t take into account the effect of current.

For WAM model from ECMWF(July 2018):
« Considerations when using output from ECWAM
Not yet modelled are the interaction of waves with sea-surface currents. In particular areas, (e.g. Gulf Stream or Agulhas current), the current effect may give rise to localised changes of up to a metre in the wave height »
From
https://confluence.ecmwf.int/plugins/servlet/mobile?contentId=131397261#content/view/131397261

For WWW3 model it seems to be different (March 2019):
https://github.com/NOAA-EMC/WW3/wiki/Manual
Page 1
« The model [....] computes other transformation processes such as the effects of surface currents to wind and wave fields, and sub-grid blocking due to unresolved islands »
Page 163
« 3.9 Winds and currents
Model input mainly consists of wind and current fields. Within the model, winds and currents are updated at every time step ∆tg and represent values at the end of the time step considered. »

In any case it would be much better for you to sail downwind and down swell. But this is quite tricky in the Agulhas current area, the swell being mostly from SW. Don’t you plan a stop in Durban?

Concerning receiving data via satellite phone:
https://community.windy.com/topic/6601/offline-use-of-windy

@idefix37
Thank you!
0_1530858211298_70a66faf-e505-426c-b84e-5ee6ce3190ce-εικόνα.png
@administrators must fix it

@tubbssurf ECMWF-WAM and WW3. We use both and you can choose