  The work analyses the error in current retrievals from images of marine
radars. The study is based on simulations of waves interacting with a shear
current. The measured dispersion is related to the underlying
wavenumber-dependent effective current. The highest tested radar antenna (H=45
m) with vertical polarization performed the best. For that case the root mean
square error was at most 0.05 m/s above the one for the simulated wave field
without imaging mechanism. The observation time of 20 minutes was compared to
shorter windows. Depending on the needed accuracy, the time may be reduced to
five minutes, associated with an loss of accuracy below 12%. The study shows
the error of the current reconstruction depends on the shape of the profile and
varies considerably from realization to realization
