IHO S-111

IHO S-111 is the Surface Currents product specification in the S-100 family, carrying the speed and direction of surface current as a gridded, time-varying field that an S-100-capable ECDIS can display and use. It lets the ECDIS show set and drift at the ship’s position for the time of passage rather than the officer reading them from tidal-stream atlases or chart diamonds. Overlaid with S-104 water levels and S-102 bathymetry, S-111 supports accurate course-to-steer and leeway allowance through tidal gates and across estuaries. Like the rest of the S-100 family it coexists with the S-101 ENC, which remains the base chart.