Sonar navigation system and method

Abstract

A method for pre-determining an underwater objects GPS position using a rotatable scan sonar unit linked to a boat, magnetic compass and GPS receiver. This system determines the underwater objects GPS position using the objects distance, compass heading and a GPS receiver/sonar on a boat. This system will provide real time longitude and latitude positions of underwater objects seen with sonar at a distance from a boat, and will allow for precise autopilot navigation or fixed position fishing. The system can also be used to correct for GPS errors when using previously stored waypoints positions of an object. The computer determines an objects underwater GPS position using a sonar transducer and mounted on a 360 degree movable mechanism such as a trolling motor unit, or phased array of transducers and a compass to provide heading information and formulates the objects position based on the distance and heading of the object in relation to the boats current GPS position.

What is claimed is: 
     
         1 . A system for controlling the position of a boat, the system comprising:
 a sonar transducer;   a display configured to display sonar information corresponding to an underwater object;   a trolling motor configured to mount to the boat; and   a processor in communication with the sonar transducer, display, and trolling motor, wherein the processor is configured to receive an input corresponding the displayed underwater object, determine a relative position of the displayed underwater object, and control the trolling motor to hold the position of the boat at a set distance from the displayed underwater object.   
     
     
         2 . The system of  claim 1 , further including a GPS navigation system configured to determine the current geographic location of the boat, wherein the processor is configured to use the relative position of the displayed underwater object and the current geographic location of the boat to control the trolling motor to hold the position of the boat at the set distance from the displayed underwater object. 
     
     
         3 . The system of  claim 1 , wherein the display is further configured to receive an input from a user to define the set distance from which the position of the boat is held. 
     
     
         4 . The system of  claim 1 , wherein the set distance is user defined. 
     
     
         5 . The system of  claim 1 , further including a compass operable to determine a heading of the boat, wherein the processor is configured to use the determined heading of the boat to determine the relative heading to the underwater object. 
     
     
         6 . The system of  claim 1 , wherein the sonar transducer is configured for attachment to the trolling motor. 
     
     
         7 . The system of  claim 1 , further including a wind detection device in communication with the processor to determine wind direction, wherein the processor is configured to use the determined wind direction and the relative position of the underwater object to control the trolling motor to hold the position of the boat at the set distance from the displayed underwater object. 
     
     
         8 . A system for controlling the position of a boat, the system comprising:
 a sonar transducer;   a display configured to display sonar information corresponding to an underwater object;   a trolling motor configured to mount to the boat;   a GPS navigation system configured to determine the current geographic location of the boat; and   a processor in communication with the sonar transducer, display, trolling motor, and GPS navigation system, wherein the processor is configured to receive an input corresponding the displayed underwater object, determine a relative position of the displayed underwater object using at least the current geographic location of the boat determined by the GPS navigation system, and control the trolling motor to hold the position of the boat at a set distance from the displayed underwater object   
     
     
         9 . The system of  claim 8 , wherein the display is further configured to receive an input from a user to define the set distance from which the position of the boat is held. 
     
     
         10 . The system of  claim 8 , wherein the set distance is user defined. 
     
     
         11 . The system of  claim 8 , further including a compass operable to determine a heading of the boat, wherein the processor is configured to use the determined heading of the boat to determine the relative heading to the underwater object. 
     
     
         12 . The system of  claim 8 , wherein the sonar transducer is configured for attachment to the trolling motor. 
     
     
         13 . The system of  claim 8 , further including a wind detection device in communication with the processor to determine wind direction, wherein the processor is configured to use the determined wind direction and the relative position of the underwater object to control the trolling motor to hold the position of the boat at the set distance from the displayed underwater object.