The strengths and weaknesses of centimetre, (I Band), millimetric (Ka band) and EO systems (daylight TV, Thermal Imager Sensors) are discussed, as applied to both the problems of acquiring and tracking naval threats, in order to achieve optimum engagements with Command to Line of Sight (CLOS) weapons. The limitations of the centimetre, millimetre and EO bands with varying target heights, seastates and visibility conditions are identified, including multipath geometry, filtering to counter multipath and utilisation of EO sensors in the Naval environment worldwide. Mechanisms of combining both Radar and EO Sensors to produce an accurate differential tracking output (target to missile), in order to control a CLOS missile are described, together with filter configurations allowing a true differential output to be produced, de-coupled from sensor sightline motion. This includes the application of sensor merging, Kalman filtering and Command Off the Line of Sight (COLOS) techniques. Finally there is a description of both an in-service and projected fire control system controlling a Point Defence Missile System (PDMS), including the results from a practical demonstration of multi-sensor tracking of an air target in a sea going environment.