
Originally Posted by
away
Even with contour tracking, the fisher is operating within the margin of error of the plotter. Bear in mind that most of the time, the plotter is pretty accurate. It is mainly when almost at a standstill that the problem you describe is most pronounced. Here is something that you can try. When leaving to go fishing, turn the unit on. When you get to the lake, save the trail that the plotter has recorded. Do this each time you go fishing. After a few trips, display all of the saved trails. You will see that even though you are driving the same route, within a metre or so of being on the same course, the trails will not line up with each other exactly.
When zoomed in you will see that the trails may be separated by as much as the three to five metre error of the plotter. Even when contour tracking, the fisher is not going to hit the desired mark every time and that is why the plotter should be used in conjunction with the sonar in these situations. The plotter will get you close and the sonar will let you home in. Let's face it, if you could get bang on the spot every time, then they wouldn't call it fishing, they'd call it catching!
Re: handle on the trolling motor. This is most unlikely to be affecting the operation of the plotter (though you could check this by checking the GPS status when the handle is over the unit.) The pattern of GPS satellites in orbit is random, but generally spread so that there will be satellites overhead, partially overhead and on the horizon. Only three satellites are required to obtain a "fix", though the more satellites that are in view, the better the fix.
Cheers