Regardless of make or model, a side imaging transducer has to have line of sight to anything it is to report.
If midship, it should be below the lowest point of the hull to work effectively both ways. It can be off the side, or below the centerline.
If it is in front of or back of the hull then it just needs to be submerged so that it does not catch air in the waves.
If it is partially obscured in a scupper type mount, it will not be functional as a side imager. Down imaging should work fine.
Good luck, Phill