Abstract: This disclosure provides an image processing device, which includes a relative trail image memory for storing a relative trail data group indicating relative changes in position of a target object detected by echo signals obtained corresponding to detection signals transmitted while changing a transmitting azimuth direction, with respect to a transmitting position from which the detection signals are transmitted, and an approaching target object determination processing module for determining whether the target object detected with the detection signals is an approaching target object that approaches the transmitting position based on relative trail data existing on the same sweep line among the relative trail data group stored in the relative trail image memory.

Abstract: A fishfinder data display device is provided. The display device includes a memory for storing fishfinder data obtained by a fishfinder detecting underwater and a location where the fishfinder data is acquired so as to associate the fishfinder data with the location, a display unit for displaying an image created based on the fishfinder data, and a controller, when an operator performs a specifying operation to a predetermined part of the image displayed by the display unit, for reading the location corresponding to the fishfinder data based on the specified predetermined part of the image from the memory, and causing an autopilot device to execute an autopilot operation with the location as a destination.