I lost a one of a kind racing propellor in a river 7 feet deep. I have an underwater camera and I know within two hundred yards of where it is. Instead of wandering the area I want a gps that shows where I have been with a line so I can drive a straight line then follow closely next to it on the next path. I had a fishing gps 15-20 years ago that had this feature but it got a quick saltwater bath and died. Thanks in advance!