US Patent 7355518 Cordless lanyard system using e-field

A monitoring system detects the presence or absence of a marine vessel operator within a defined zone near the helm of a marine vessel. The detection is accomplished through the use of a provision of an e-field and the detection of e-field strength by a receiving antenna system. When the operator is in the proper helm position, the e-field strength is diminished by the presence of a portion of the operator's body within the e-field zone.