@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