My X-75 (on the bow) is very sporadic in shallow water (under 8 feet). It works fine when I am in deeper water, but works some and flashes a lot (with the digital number of the last reading) when I get into shallower water. The transducer is mounted on the transom, and the problem is occuring when I am not running the big motor. Could it be the sensitivity (I have tried messing with that, to no avail)? Any ideas?