Garmin 540s Transducer not responding

[oceanpearl]

Hello all,
I have a problem with the Garmin 540s transducer/sounder responding the depth at speeds over 7 knots. I have checked all the wiring to make sure nothing is lose, I have tried adjusting the angle of the transducer to see if maybe it was hitting the bottom of the boat on plane. The only conclusion I could come up with is the plastic transom mounted transducer is only good for trolling speeds hence why it does not operate correctly at anything above 7 knots. What happens is the sonar screen will be reporting the depth 15 ft deep then once you hit that magic speed it will just continue to flash 15 ft and not respond back with a new number until you slow back down. Sometimes I will be anchored in 12 ft of water and all the sudden the shallow water alarm will go off saying we are in 4 ft of water.

I have thought about a Garmin thru-hull sounder but I don't know if this is any better or not.

Any thoughts/suggestions on this would be very helpful.

Thanks

 

[seasick]

Hello all,
I have a problem with the Garmin 540s transducer/sounder responding the depth at speeds over 7 knots. I have checked all the wiring to make sure nothing is lose, I have tried adjusting the angle of the transducer to see if maybe it was hitting the bottom of the boat on plane. The only conclusion I could come up with is the plastic transom mounted transducer is only good for trolling speeds hence why it does not operate correctly at anything above 7 knots. What happens is the sonar screen will be reporting the depth 15 ft deep then once you hit that magic speed it will just continue to flash 15 ft and not respond back with a new number until you slow back down. Sometimes I will be anchored in 12 ft of water and all the sudden the shallow water alarm will go off saying we are in 4 ft of water.

I have thought about a Garmin thru-hull sounder but I don't know if this is any better or not.

Any thoughts/suggestions on this would be very helpful.

Thanks

Two things can make this happen, assuming the ducer and wiring are OK,: The ducer is loosing contact with the water or it is being swamped with turbulence(air bubbles). If this has always happened, the ducer may be mounted in a bad location or is not adjusted correctly.
I am not sure about the low water alarm at rest though. That shouldn't happen unless the ducer is coming out of the water. That might happen as you move around the deck and from side to side.
If you operated the motor in reverse, that can cause turbulence and bubbles that will confuse the ducer. So if you are not moving and haven't run the motor and have not been following another boat and the depth cuts in and out, I would suspect an electronics issue;bad ducer, wire, connector or the head unit itself. Its tough to isolate without either another head or another ducer.

 

[oceanpearl]

Thank you seasick,
I will adjust the angle the transducer sits at and perhaps even move it. You could be right about turbulence messing it up, that never occurred to me until you said something.

 

[seasick]

Thank you seasick,
I will adjust the angle the transducer sits at and perhaps even move it. You could be right about turbulence messing it up, that never occurred to me until you said something.

Each transducer has a specific starting point for adjustment. In general the rule of thumb is that the center line of the transducer should be 1/4 inch below the bottom of the hull and the ducer's bottom should be parallel to the seabed ( starting with it parallel to the hull is OK.)

In addition, the ducer should be at least 8 inches or so away from the center line of the motor (single outboard) and not in line with things like strainers, hull steps etc.
The first thing I would check is that the ducer is actually set at the right depth as mentioned above).

 

[qmarine]

If this is a single engine, which side of the transom did you mount the transducer on?
Starboard side is recommended to minimize effect of prop wash. If mounted to port this could be your cause.
Otherwise inspect for other causes of bubbles and turbulence ahead of the transducer.