Depth Sensor or FI50 displays



Hi. I am at present sailing around Indonesia. I have Navnet 3d system on board. MFD8 FI50 Displays and Time Zero. I was devastated to find that when the depth is greater than approx. 130 mtrs the display just shows dashes. But intermittently shows shallow depths that can't be possible. This is very disconcerting when depths here go from 100 + mtrs to 10 mtrs in just a boat length. Is it the sensor or the system?. The sensor was supplied with the sailing package (DST200)
Depth sensors can bounce off items in the water below the boat. This is normally bottom, but not always. You would need a sounder to better view on what is going on below the vessel. Using charts and other sources of navigation is very important. Overall if this happens very often, you may have in installation problem involving water turbulence.
We contacted you around this time, you gave us the phone number of a technician at Furuno whom we called. He stated he did not know about this issue and suggested the fault would be with the transducer, and to be honest, he didn't seem to be too interested.

We are passage making north, currently at Ketchikan. All the way, the display is correct (checking against our other sounder and charts) until we get into water deeper around 200 metres when it will display the horizontal lines briefly before giving false shallow readings again. We sent you a photo, showing the track we were making on the chart, with depths of 150 metres or so, with the depth sounder display and it's reading next to it...13.4 metres.

Please, we would like to investigate why this is so. It is nerve wracking We were in an anchorage the other day negotiating a narrow channel which should have had a depth of 4 metres...the depth sounder had a reading of 1.2 metres...our thoughts first up are ones of alarm, then secondly, 'is this thing 'crying wolf''! We were in 1.2 metres as it happened, but you can understand, we don't trust it now.

Also, we have noticed recently...when we first turn the instruments on...the display shows it doing it's start up checks..the depth then comes up, and right where the decimal point is in the depth reading appears the number 4 briefly, it then disappears......
First off, if the FI50 is connected to a "smart sensor" as opposed to a repeater to the other sounders then the instrument is working to spec. The smart sensors are high frequency, low power transducers designed to work excellent in skinny shallow water. They were not designed or capable over 600 feet. In fact I would not rely on their reading over 300' , but as observed they were very accurate in skinny water.
This forum is designed to support end recreational customers. If you are a dealer, you should work directly with the tech support of your local distributor for any assistance. Dealer are welcome to answer and assist customers here.