Location: Eastern Ontario | I use the Navionics + card ( but not the sonar view ) for areas with government charting like the Great Lakes & ST Lawrence, Ottawa R. and Trent Severn System. For small inland lakes that I fish frequently and there is no good mapping I do my own using Insight Genesis. For my home lake Navionics uses a 1968 map that was made for calculating water volumes with 10 foot contours . When you switch to the sonar view you get contour lines out of someones dreams. Major rocks are off by 100 yards and many humps not shown. |