An apparatus comprising: a transducer assembly configured to emit a sonar beam, receive return echoes of the sonar beam, and convert the return echoes into raw sonar data, wherein the transducer assembly is configured to be affixed to a watercraft; position sensing circuitry configured to determine positioning data, the positioning data being indicative of a position of the watercraft; processing circuitry configured to: receive the raw sonar data and the positioning data, convert the raw sonar data into range cell data based at least on amplitudes of the return echoes; make a location-based association between the range cell data and the positioning data, plot the range cell data based on respective positions derived from the positioning data and rotate the range cell data based on a direction of movement of the watercraft to generate adjusted range cell data, and convert the adjusted range cell data into sonar image data; and a display device configured to render at least a portion of the sonar image data as an overlay over presentation of a geographic map at a position and oriented in the direction of movement of the watercraft, wherein the position of the sonar image data on the geographic map corresponds to the position of the watercraft associated with the sonar image data; wherein, in an instance in which overlapping range cell data are associated with a same location, the display device is configured to render the portion of the sonar image data at the same location corresponding to the range cell data with the peak value for the location. a transducer assembly configured to emit a sonar beam, receive return echoes of the sonar beam, and convert the return echoes into raw sonar data, wherein the transducer assembly is configured to be affixed to a watercraft; position sensing circuitry configured to determine positioning data, the positioning data being indicative of a position of the watercraft; processing circuitry configured to: receive the raw sonar data and the positioning data, convert the raw sonar data into range cell data based at least on amplitudes of the return echoes; make a location-based association between the range cell data and the positioning data, plot the range cell data based on respective positions derived from the positioning data and rotate the range cell data based on a direction of movement of the watercraft to generate adjusted range cell data, and convert the adjusted range cell data into sonar image data; and receive the raw sonar data and the positioning data, convert the raw sonar data into range cell data based at least on amplitudes of the return echoes; make a location-based association between the range cell data and the positioning data, plot the range cell data based on respective positions derived from the positioning data and rotate the range cell data based on a direction of movement of the watercraft to generate adjusted range cell data, and convert the adjusted range cell data into sonar image data; and a display device configured to render at least a portion of the sonar image data as an overlay over presentation of a geographic map at a position and oriented in the direction of movement of the watercraft, wherein the position of the sonar image data on the geographic map corresponds to the position of the watercraft associated with the sonar image data; wherein, in an instance in which overlapping range cell data are associated with a same location, the display device is configured to render the portion of the sonar image data at the same location corresponding to the range cell data with the peak value for the location.