If the ScanFish undulates or flies unstably in Follow Seabed mode, this is not normal even in strong currents. Work through the following:
- Cable length vs depth: confirm you are using an appropriate tow-cable length for the operating depth. An unsuitable cable-length / depth combination is a common cause of unstable flight. Check cable configuration manual for theoretical cable length values: ScanFish cable configuration : EIVA Support
- Altimeter: make sure the altimeter type is correct.
- Conditions: note when the instability happens (for example at line turns or crossings).
To investigate further, collect the Flight log files (by default in C:\temp\ScanFish\Log) and send them to EIVA support, with the cable lengths, operating depths and an indication of when the problem occurred.