Depth sounder strange readings fault (Navico Corus display)

[FairweatherDave]

I've searched up some old threads but no-one has described this particular fault my depth sounder has developed. Basically it spontaneously changes units from metres (and being accurate) to weird readings/units and then flicks back to normal. I have read about strange readings being caused by air in the water, and particularly silty mud bottoms, but I haven't changed my sailing habits (location) mainly inside Chichester harbour and this seems more like a fault. And it is not like the display goes blank.
I have also noticed a little condensation in the display unit which I guess might be part of the problem, but I have read that that should not necessarily be a problem. (I also read that switching the backlight on on the display might help it dry out). I have read about how to listen to the transponder and will do that next time, though clearly it is working (I think it is an Airmar judging by all the blurb in front of me and it looks like it might be reasonably recently installed (compared to the display units).

So any comments possible solutions very welcome. The technical stuff that I have read so far is not second nature to me but the depth is the one instrument I use alongside hand held GPS, so installing a stand alone depth sounder or replacing the display unit are possible challenges, but only if I have to. I'm a real electrics amateur! Thanks for any help.

PS Next time I dry out I can clean the underneath of the transducer but I really don't get how that would make the units switch, (and it is only accurate when reading metres). (Boat out over winter and antifouled and in end of March)

 

[Champagne Murphy]

https://plus.google.com/109231021896870461088/about?gl=uk&hl=en

These are the guys to ask. They took on the remaining spares when Simrad bought Navico and effectively shut it.Very knowledgable and helpful, Terry was the real techy I recall. Ber in mind the gear is getting on a bit now and replacement may have to be an option.

 

[FairweatherDave]

https://plus.google.com/109231021896870461088/about?gl=uk&hl=en

These are the guys to ask. They took on the remaining spares when Simrad bought Navico and effectively shut it.Very knowledgable and helpful, Terry was the real techy I recall. Ber in mind the gear is getting on a bit now and replacement may have to be an option.

Thanks for that. I have actually contacted them before when dealing with the Corus chartplotter, again hitting the obsolescence wall, which makes sense when all the kit is interlinked, but I had forgotten them. I live happily without a chartplotter but depth I rather like to know....

 

[FairweatherDave]

Just spoken to Terry at Odin Marine for the second time and again really helpful. I now have a plan of action before declaring the kit obsolete. It starts with cleaning the transducer and removing the soft antifoul that may or may not be on it (can't remember what I did). Terry's view was hard antifouling is okay on transducers but not soft. Hopefully it is simple as that. Otherwise I will be checking all the connections and remaking them. However I have a confession..... in my initial post I said the display was changing units between metres and feet, because I thought that is what I had seen. However this weekend the depth was either reading correct or going nuts but it was all in metres.

 

[ChattingLil]

I had this on my previous boat. I'm also a technobimbo so struggle to find the right words, but maybe you will see what I mean. I had 4 instrument heads each set for a different function and the depth was the one of the end of a daisy chain. It turned out it was knackered connections. The one on the end finally conked out completely, but I was able to make the next one along read the depth and this worked well (and still is as far as I know).

 

[Billjratt]

Have a quick inspection along the length of the transducer lead (and power lead while you're at it) I had intermittent loss of echo especially in deep water, turned out to be chafe from the steering gear. Once fixed - no problems.

 

[FairweatherDave]

Cheers ChattingLil, as a technohimbo (had to look that up I'm feeling encouraged that I'll sort it..... just got to get the boat to myself and get into those lockers, and Billjratt thanks too. Good name for the job in hand