You might try turning the Noise Filter Off unless there is RFI you're trying to filter out ...(unfortunately...the Noise Filter "can" filter out good echoes also)...

Turn the Sensitivity up in Clear Mode ...until you see an acceptable amount of clutter on the screen...("acceptable" is different for everyone)...

Set the "Beam Select" to 200kHz/83kHz ... The wider 83kHz 60° cone will be more likely to show arch type echoes in that shallow of water ...because it allows the fish to be in the cone longer...

Set Chart Speed to 10 using 2d...(remember this is a global setting so it will be way too fast for SI/DI)...

I agree we shouldn't have to use the "Dual Beam" Transducer Select choice when viewing 2d...but it is ...what it is...(HB will eventually get this straightened out)...

Rickie