Intermittent Depth Sounder

[Roadapple6]

Hi...we have a Beneteau 323 with a ST40 Bidata unit. Everything works fine (speed, temperature, etc.) with the exception of the depth sounder. The display shows horizontal lines only for depth. However, recently it mysteriously started to work as we motored out of port. The depth sounder worked well for about 10-15 minutes until we anchored and shut off the engine, then the display showed the horizontal lines as described above and hasn't worked since.

Thanks for your help.

[CapTim]

well, I can't speak to your specific situation.. but there are two fairly common problems with depth finder installs:

problem a: the sending unit is installed over a void in the hull. Examples include centerboard trunk, cored hull, wire/pipe conduits, and zinc anodes

Problem b: The sending unit was installed using epoxy which had one or more air pockets/bubbles in the puddle, and said air pockets did not release.

There are dozens of other things that could be wrong. Heck, it might even just be as simple as the sending unit wasn't properly mounted. I've even seem them held in by brackets or screw-tabs. Have you set eyes on the unit to see how the install looks and where it is?

[Roadapple6]

Thanks for your reply. I should have mentioned that we have a thru hull transducer. We have attempted to clean the face of the transducer. It just seems strange that it would work perfectly for a brief period of time.

[SeaFever2000]

The fact that your depth transducer is the thru' hull type, eliminates many of the suggestions we would have made for the case when the transducer is installed differently.

Given that transducer install here are some of the things that come to mind:

-- Wiring issue. Trace the cable from the transducer to the display. If there are extension connectors please check that those are snug. Check the cable wherever it is making a sharp turn for kinks. Have someone looking at the display while you wriggle the cable and see if the display starts up when you are wriggling the cable at a specific location. IF you do find a location of the cable that is damaged then you can cut a portion and repair it.

-- Connection issue - Check the connector at the display unit and make sure the connections are not corroded.

-- transducer issue - This is a difficult one to troubleshoot. One way to look at it is that if everything else fails it is the transducer.

Hope this helps.

[kwaltersmi]

Check the transducer surface on the outside of the hull very carefully. Also follow the cable from the transducer to the display unit and look for anything that could cause electrical intereference. IIRC, the "----" display on most depth finders indicates that the display isn't receiving a signal from the transducer, as opposed to other error codes that can be displayed.

You might also look on the display unit for a sensitivity adjustment. Sometimes too much sensitivity can make the unit see two bottoms (one being false) and too little sensitivity can make the echo get lost. If there's a an adjustment, make very small changes until you get the display working.