First time out with my 73sv on a real hot day. I have heard that sometimes you can see the thermocline on a graph. Anytime i was in water deeper than 20ft I would have a line around that mark all the way to the bottom. Whenever I was in water shallower nothing. At first I thought it might be interference from my Lowrance flasher that I use for high speed runs so I cut it off and still saw it. Has anybody else seen this?