Sound contacts on the surface?

[Ducimus]

So then is it possible to adjust this geometric search area when the sub is surfaced? If so, make it a smaller area thus clipping the sonar into a tighter circle of detection area?

Shame im at work, or id make with my MS paint skills again. Trying to think of a metaphore here.....

Pretend your washing dish's for a moment (cause the wifes too lazy, or whatever), you have a plate or some other round object in the water, and little bits and pieces of food float on the surface, and underneath in the water itself.

The plate is submerged, do these floaty bits get on the plate?
No.

While the plate is totally submerged do the bits in the water get on the plate?
Yup.


If you lift the plate, closer to the surface so its just incontact with the surface of the water, do the floaty bits get on the plate then?
Yup.

Are the submerged bits still getting on the plate?
Yup.


You could use a smaller in diameter plate, and hence have less surface area for bits to come in contact with, but the action of getting surfaced bits or not, still depends on raising the plate, and the plate is smaller both submerged and surfaced.

If that makes any sense.