You'll find a lot of fall off of the signal past 120' to 150' where your image is dark off to the sides in shallower water. For general searching I set mine to that and then when I want more detail I mark the spot so I can cruise back in close with the sides set shorter. I'll even adjust it a second time from there. Earnst is right, some times you'll see more interesting detail if you can get the object in the water column but you have to find it first.
This is going to seem contour intuitive but in deeper water, 50 or 75 plus, I think you might get good side readings even further out cause of the geometry but I'm not going to go into it here.

WarrenMN