A production method for a headline sonar cable (20, 120) that exhibits a high breaking-strength and lighter weight than a conventional steel headline sonar cable. Producing the headline sonar cable (20, 120) is characterized by the steps of : a. providing an elongatable internally-located conductive structure (34, 134) that is adapted for data signal transmission; and b. braiding a strength-member jacket layer (52) of polymeric material around the structure (34, 134) while ensuring that the structure (34,134) is slack when surrounded by the jacket layer (52) The structure (34, 134) of the cable (20, 120) retains conductivity upon stretching of the jacket layer (52) surrounding the structure (34,134) that lengthens the cable (20,120). For one embodiment of the method a conductor (20) wrapped around a rod (24) and enclosed within a sheath layer (32) forms the structure (34, 134). For another embodiment of the method a braided conductor (122) enclosed within a braided sheath (124) and a polymeric layer (132) forms the structure (34,134).