F&F,
If you're asking about a contour on the navigation display, all I'd add to the above replies is to mark waypoint at the areas your tend to over shoot for future reference. If you're referring to physical contours and trying to follow them using the SI sonar display, it helps to have the transducer at the front of the boat. If it's mounted on a trolling motor (or a similar mount that can be rotated), you can turn it slightly to "peak ahead". Again, marking turns with waypoints will help for future use. In general I get a better reading of a contour on the SI display by "shooting" (running it) from the shallow side when I am "mapping it out" using the towfish.
Dog Leg ...
(http://limbatus.net/linked/DogLeg-01-y-tmf.jpg) (http://limbatus.net/linked/DogLeg-01-yf-lg.jpg)
< click to enlarge > (http://limbatus.net/linked/DogLeg-01-yf-lg.jpg)
Darrell