The paper analyzes the electromagnetic (EM) radiofrequency (RF) radiation hazards onboard a ship arising from shipboard radiocommunication and navigation equipment. EM field effect on personnel and equipment can be harmful if field levels exceed the threshold values. These fields need to be controlled for proper protection. Ships are equipped with lots of EM RF radiation sources with different frequencies and output power levels. Typical shipboard EM RF radiation sources include: terrestrial radiocommunication transmitters, navigational radars and satellite ship earth stations (SES). Examples of these sources are analyzed in the paper. EM field estimation using simple worst-case calculation is given for a typical HF transmitter, X-band navi...