A78 - Depth Reading Updating VERY VERY SLOWLY (See Attached)

[SouthFLPA]

My A78 has only been out on the water a few times now, but I have had this issue since day one. I thought a software update might take care of it, but I have the latest version installed and it it still doing it.

The Issue: I can mark vivid bottom, structure, fish and even see my vertical jig down to 150'. What I can't get is a reliable depth reading. It changes randomly (sometimes takes 10 minutes or more) instead of continuously (like a fishfinder is supposed to). I went ahead and ordered a new transducer, just to rule it out, but I would like some feedback on what might cause this phenomenon.

I took a couple of screen shots to illustrate the issue. You can see that the depth reading is stuck at 237', but the actual bottom is more like 255'. Less obvious, but the other screen shot shows 202', when the bottom is actually displayed as a feet deeper.

[SouthFLPA]

Hi Chuck,

I installed the latest version of Lighthouse II that was released March 2016. I only used the unit once right after I installed in late 2015. It was a brief trip, but I don't recall there being an issue with the depth updating then. So, I don't know if the March 2016 update caused the issue or if the issue was already present.

I have the unit mounted under a Hobie Pro Angler 14' kayak. Hobie actually has a cut out under the hull designed for transom mounted transducers. I have the CPT-100 mounted the same way as a friend who has the same kayak with a dragonfly 7 and the same or similar transducer set-up. He doesn't have this particular issue.

This isn't my area of expertise, but I am a control system engineer and this seems like a software issue with the A78, rather than a hardware issue with the transducer.

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum SouthFLPA,

The transducer should be inspected to ensure that it is not fouled. Should this not be the case, then it would be recommended the a78 MFD be tested with another transducer suspended over the side of the hull or that that the MFD be sent to Raymarine’s Product Repair Center to be bench tested/serviced.