I know for an almost certian,and probably true fact, you can purchase a gps unit a small, hard to see unit, put it in a boat, hide it- someone elses boat that is, and go back later, hook it up to the ole computer and down load there tracks, just like the black box in some new cars to keep track of children. yep seen that done at bucksaw last year, or that's what I thought I saw. so knowing that and now knowing this (your post) I know now to fish all some one elses spots when the double D is arround. I still snicker when I see your handle. double Ds 20 dollars is my bid