Abstract: A security system for use on a boat with propulsion means, such as an engine, has a base unit mounted on the boat and a personal unit attached to the driver and each passenger. The base unit has a first radio unit and an RFID-reader with an antenna, and is in wireless communication with the personal unit. The personal unit has an RFID-transponder and a second radio unit, both with a unique identity, and a biometric unit that at correct attachment to the person send a biometric signal to the base unit. The communication utilizes RFID technology within a near range, but the system automatically handovers to radio technology when a larger area is to be covered. A field from the RFID reader activates the RFID-transponder, and if the identity is correct the person is registered as the driver and may start the boat. When the base unit loses communication with a personal unit different measures are initiated, such as activating an alarm.