I know SV is side veiw and CV is more detail narrow cone.
Not sure where you got that idea. The SV has narrower beam angles and is by far the better transducer for "detail" of the two.
The SV uses the GT22HW-TM CHIRP transducer. It has 3 transducers... Two (2) for side scan and one (1) center: 16 and 24 degree cone angles
The CV uses the GT20-TM "traditional" transducer which has a single transducer on center: 15 and 45 degree cone angles
Main question is does the SV work better for mapping in shallow water. I want to chart a river between 3-15ft deep and a lake goes down to 100ft.
From what I'm seeing it really doesn't matter.
Taking single point snapshots of depth and position, then "connecting the dots" for lack of a better word, to create a contour.
This methodology is heavily dependent on water levels, positioning accuracy, speed and the "distance between passes" to generate an accurate contour of the bottom.
