Originally Posted by
CrappiePappy
As I understand it, SI works "best" at speeds around 3-5mph .... but, slower speeds just elongate the white "spots" (fish) into white "streaks". If the unit has the capability of changing chart/ping speed, then matching that speed with the boat speed can somewhat counteract that stretching effect. Check your user manual to see if/how you can change your chart/ping speed.
I don't have a SI unit, this is just some things I've heard/read about them. My current unit is a regular Hook 7 (2d/DI/GPS/map) ... which I mainly use as a DI unit. (I have little to no use for 2d imaging) Unit was purchased to replace a Lowrance Elite 5 DSI (when one of the pins in the connection port broke off).