We had an issue with the Garmin 750S sonar crashing and not finding the floor if we went over about 10 knts. Was a total pain! After some research, we found it was a cavitation issue, ie: Air under the boat was getting under the transducer and causing it to fail.
As you can see in the pics, it was mounted too high. We dropped it about 30mm and now it’s always under water and never loses the bottom, even up to 70kph!
(I’ll get a photo of the new position)
