Mercury - SC100 Data Harness 30-Foot SmartCraft Link Extension 84-880756T30. Overview. Some boats have big helms, long consoles, or layout obstacles that make the standard SC100 data link fall well short. The Mercury 84-880756T30 SC100 Data Harness adds a full thirty feet of reach, giving you the slack you need to run the SmartCraft connection cleanly from one gauge to another-even on wide dashes or larger offshore rigs. It keeps the wiring relaxed and makes long runs feel a lot less cramped.. K