'Watchdog' is an on board satellite based wireless communications, location tracking and monitoring system incorporating Orbcomm, an extensive network of Low Earth Orbit (LEO) satellites and SONY Ericcson/Cingular for GSM service. It has been developed to allow owner/operators to check engine performance, survey on board network systems, and track vessel position from the comfort of a distant office, ensuring their investment is being used to maximum effect. Among the functions which can be monitored are heading, speed, trip log, sea and air temperature, barometer, water depth, fuel consumption, fuel remaining, engine hours run, system voltage, automated bilge alarm and Geofencing, which warns of unauthorised vessel movement.