Garmin 400C Fishfinder

[Bonker43]

I'm having a problem with my Garmin 400C Fishfinder. As soon as I hit around 8mph and more the display shows the bottom looking like a mountain range even though it should show it's flat. Garmins suggestion to conduct a hard reboot of the unit did nothing. The strange thing is this only occurs in fresh water. Out in the chuck it works fine. Anybody have any suggestions.

Thanks.

 

[ericl]

I'd check to see if any firmware updates are available & install them.

 

[Marsman]

Thats weird... On one of my sounders I replaced the transducer to fix some issues. Feel the bottom of the transducer and see if it is all smooth. One of mine I used 800 wet sand paper and brought it back to new.

Cheers, Rob