Analysis of the electromagnetic environment on topside of a ship is needed for optimal arrangement of all kinds of antennas to be installed on the shipboard in order to minimize the probability of EMI of equipment and subsystems in real ship after construction phase. In this paper we analyze the characteristics of electric-fields such as radiation patterns and near E-fields of V/UHF antennas installed on a shipboard. We compare simulated results with measurements on the real ship for near E-fields to verify the reliability of the computed electromagnetic environment. Although there are various factors causing errors such as cable loss and impedance mismatching etc. when measuring near E-field, both data show similar trends in the range of the acceptable tolerance.