Selectable display modes for live sonar

A marine system for a watercraft, the marine system comprising:

• a sonar transducer assembly comprising a plurality of sonar transducer arrays,
• wherein each sonar transducer array comprises a plurality of transducer elements configured to operate at a fixed phase shift and vary in frequency so as to beamform multiple sonar return beams for receiving sonar return data from an underwater environment relative to the watercraft;
• a marine electronic device comprising:
• a display;
• a processor;
• a memory;
• and
• a communication interface configured to receive sonar return data from the sonar transducer assembly;
• wherein the processor is configured to:
• receive first sonar return data from the sonar transducer assembly, wherein the first sonar return data corresponds to a first volume of the underwater environment;
• generate and present a live sonar image based on the first sonar return data, wherein the live sonar image provides a representation of the first volume of the underwater environment, wherein an entire portion of the live sonar image corresponding to the first volume is continually updated in real-time;
• receive an indication of user input defining a portion of the live sonar image, wherein the portion of the live sonar image corresponds to a second volume of the underwater environment that is within the first volume and less than the first volume;
• and
• generate and present, based on the portion of the live sonar image, a second live sonar image based on second sonar return data corresponding to the second volume of the underwater environment, wherein the second sonar return data is a subset of data within the first sonar return data and is less than the first sonar return data.

A method for presenting sonar imagery on a display of a marine system of a watercraft, the method comprising:

• receiving first sonar return data from a sonar transducer assembly comprising a plurality of sonar transducer arrays, wherein each sonar transducer array comprises a plurality of transducer elements configured to operate at a fixed phase shift and vary in frequency to beamform multiple sonar return beams;
• generating and presenting a live sonar image based on the first sonar return data, wherein the live sonar image provides a representation of a first volume of an underwater environment, and wherein an entire portion of the live sonar image corresponding to the first volume is continually updated in real-time;
• receiving an indication of user input defining a portion of the live sonar image, wherein the portion corresponds to a second volume of the underwater environment that is within the first volume and less than the first volume;
• and
• generating and presenting a second live sonar image based on second sonar return data corresponding to the second volume of the underwater environment, wherein the second sonar return data is a subset of the first sonar return data and is less than the first sonar return data.