I get the best images with my humminbird 899 if I set my depth at 4 times the actual depth of the water is showing. So if its 10' then I set my SI range to 40-50 feet. If 20' then I do 80-100 feet. This way most things in the water are to "scale" and can be seen with greatest detail. You can go way further out than that, but wont be able to see near as much.