Mercury - VesselView 70x Power Harness SmartCraft Power & Data Harness 84-8M0111668. Overview. The Mercury VesselView 70x Power Harness (84-8M0111668) supplies power and SmartCraft data from your boat's junction box to one or more VesselView 70x displays. It's the connection that keeps your system alive - delivering clean power and reliable engine information to your screens. This harness is included in complete VesselView 70x kits, but it's also available separately for replacement or expansion