Alert zones for a marine environment

A sonar system comprising:

• a transducer array configured to receive one or more sonar return signals and to convert the one or more sonar return signals into sonar data;
• a marine electronics device comprising:
• a sonar signal processor;
• a memory comprising a plurality of program instructions which, when executed by the sonar signal processor, cause the processor to:
• determine one or more alert zones for a marine environment proximate to a vessel, wherein each of the one or more alert zones is a substantially rectangular area comprising:
• an imaginary straight line extending from the vessel to a point representing a determined forward range;
• an imaginary straight line extending from the vessel to a point representing a determined depth;
• and
• an imaginary straight line extending from the point representing the determined forward range and an imaginary straight line extending from the point representing the determined depth that meet at a determined range point, wherein the determined range point is a point in the marine environment that has a horizontal offset from the vessel that is equal to the determined forward range and a vertical offset from the vessel that is equal to the determined depth;
• receive sonar data from the transducer array, wherein the sonar data corresponds to the marine environment;
• analyze the received sonar data to determine a depth line, wherein the depth line is a representation of one or more depths of an underwater floor of the marine environment;
• and
• provide one or more alerts if at least a portion of the depth line is positioned within the one or more alert zones.

A non-transitory computer-readable medium having stored thereon computer-executable instructions which, when executed by a computer, cause the computer to:

• determine one or more alert zones for a marine environment proximate to a vessel wherein each of the one or more alert zones is a substantially rectangular area comprising:
• an imaginary straight line extending from the vessel to a point representing a determined forward range;
• an imaginary straight line extending from the vessel to a point representing a determined depth;
• and
• an imaginary straight line extending from the point representing the determined forward range and an imaginary straight line extending from the point representing the determined depth that meet at a determined range point, wherein the determined range point is a point in the marine environment that has a horizontal offset from the vessel that is equal to the determined forward range and a vertical offset from the vessel that is equal to the determined depth;
• receive sonar data from a transducer array disposed on the vessel, wherein the sonar data corresponds to the marine environment;
• analyze the received sonar data to determine a depth line, wherein the depth line is a representation of one or more depths of an underwater floor of the marine environment;
• and
• provide one or more alerts if at least a portion of the depth line is positioned within the one or more alert zones.