Abstract: A maritime safety system comprising at least one transmitter unit (12, 14, 16, 18), each transmitter unit being arranged to transmit successive signals by wireless communication at pseudo random intervals and each transmitter unit (12, 14, 16, 18) having an associated transmitter range, a base station (10) arranged to receive said transmitted signals and an alarm device (20). The base station (10) is arranged to cause the alarm device (20) to generate an audible and/or visible alarm when a plurality of successive signals from at least one of the transmitter units (12, 14, 16, 18) are not detected, and the arrangement is such that when a transmitter unit (12, 14, 16, 18) is disposed a distance from the base station (10) which is greater than the transmission range associated with the transmitter unit and a plurality of successive signals are not detected, an audible and/or visible alarm is generated.