JPH0417838B

PURPOSE:To make a device have both functions of course maintenance and position maintenance and perform automatic navigation in an accurate manner, by performing sea route maintenance along a scheduled sea route with selection from point control to linear control and vice versa, while checking a shift from the scheduled sea route to the minimum. CONSTITUTION:A linear control part 1 outputs a linear control course thetal toward a scheduled sea route in calculation on the basis of a course difference between a control lineation and one's own ship position determined out of scheduled sea route data. Likewise, a point control part 2 outputs a point control course thetap. Both these output values thetal, thetap and a scheduled sea route thetao are all inputted into a declination detecting part 4. This declination detecting part 4 detects each of declinations DELTAl and DELTAp of thetal and thetap to thetao and outputs them. These declinations are discriminated for their size by a comparator 5, and select switches 3a and 3b at the larger side of output thetal, thetap are turned on. That is to say, when DELTAthetal is larger, the linear control course thetal is set down to a command steering angle, outputting it to an automatic navigating device, but when DELTAthetap is large, the point control course thetap is set down to a command steering angle and outputs it to the device.