I recently purchased the hummingbird 650 depth finder. I installed it in the hull behind the old factory puck using the recommended slow setting epoxy. The gauge does not read at all stopped or moving slow then at crusing speed it reads silly high like 100-200 ft and it jumps all around when I'm in actual 6 ft deep river? Any ideas?

I had one of those, couldn`t get it to work unless fully submerged in water (transom mount) Messed with it for weeks inside the boat . I see it is now discontinued, I think I know why, (piece of $hit)

Bought a used Livorsi , before using the epoxy I tested a spot using silicone , its been working like that for 2 years now.

Ditto of ICDEDPPL. I have had to replace two of the Humminbird Transducers in two different boats to external transducer. The one in my current boat is working, fingers crossed! I like hearing about the LIvorsi replacement....

dam that sucks, wonder if they will replace it...
Wonder how the heck I'll get it out now?