Weird depth readouts

[Robin]

Yesterday beep alarms were going crazy on board, eventually traced to depth alarms being passed going up or down past the preset values. We are in our home berth. A newly arrived visitor next door, Nauticat 33 had probably use a thruster cresting bubbles to confuse our depth transducer I thought. Depth readings were going to 600 ft and all stations between. This morning when the visitors left thry ran the engine some 10 minutes before leaving and same happened, no thruster, but once they left and cleared our area, the alarms ceased and depth readings again returned to normal. Any ideas what was going on?

 

[NormanS]

Probably caused by their sounder operating on a different frequency from yours.

 

[Robin]

Probably caused by their sounder operating on a different frequency from yours.

hadn't thought of that one, ta!

 

[prv]

Probably caused by their sounder operating on a different frequency from yours.

I would have thought the same frequency would interfere, rather than different, but concur that interfering sounders is a likely reason. I know survey boats have to turn off the “navigational” sounder when the survey gear is in use, to avoid confusing the sonar.

Pete