I still think the paint is the problem.  I know of nothing else that would
keep it from working in shallow water and work in deeper water.  If the unit
or transducer were not putting out enough power - it would be the opposite.
--
Tony
my boats at 
http://t.thomas.home.mchsi.com
"Fred Reyes"  wrote in message
  om...
 When is doesn't work, It will flash the digital depth reading, it will
 either flash the last known reading or flash "zero" if I haven't moved
 in to deep enough water to get any reading yet.
 "
 
  Check the settings.  There is a surface clutter suppression, or
  something like that, that might be causing the problem.  What does it do
  when it "doesn't work"?