Mercury - Gen I Throttle and Shift Cable 30 Foot Mechanical Engine Control. The Mercury Gen I Throttle and Shift Cable is designed for boats using Mercury mechanical control systems that rely on a direct, physical connection between the helm and the engine. Built for legacy Gen I control interfaces, it delivers consistent throttle input and clean gear engagement without the delays or complexity of electronic controls. The 30-foot length is well suited for wider boats, deeper hulls, and layouts w