Abstract: A true predicted area of danger providing a preselected miss distance between an intruding vehicle and own ship is provided. A miss distance circle, having a radius equal to the desired miss distance, is generated about the initial position of the intruding vehicle and the relative coordinates and distances from own vehicle of selected points on this miss distance circle are determined. Points of own vehicle intercept of these selected points are established and a smooth curve is drawn through these points to provide the boundary of the predicted area of danger.

Abstract: A ship steering system has a multiplicity of selectable steering stations. A continuously rotating helm at each steering station generates digital rudder control signals which cause a predetermined rudder movement for each 360.degree. of helm rotation. Steering stations are selected through a multiplexer controlled at a command steering station. The steering system is operable from the command steering station in a plurality of modes, which includes auto-pilot, helm (full-follow-up), and tiller (non-follow-up). Helm and/or tiller modes of operation are available at steering stations remote from the command steering station. The system provides for an emergency takeover from the helm or autopilot modes by automatically establishing the tiller mode when the tiller stick is moved. When in the autopilot mode an alarm system provides an alert should the course deviate from a selected course tolerance.