Mercury - Pitot/Speed Sensor Kit 100 PSI SmartCraft Speed Input 881879A15. Overview. For boats running under 80 mph, a pitot-style sensor is a simple and reliable way to feed speed data into SmartCraft. The Mercury 881879A15 Pitot/Speed Sensor Kit delivers a 100 PSI pressure signal and includes the key harness needed for systems using the round 3-pin to flat 4-pin connection. It mounts easily on a MerCruiser sterndrive transom bracket or directly on the hull near the engine, giving SmartCraft in