You cant plot a distance using the hydrophone. In a good day youd be able to say if the contact is close, medium or far but thats it, and its general direction of travel. Do do this, slowlly scan untill you first hear something, then scan further to see where to contact fades. This small arc encompassing a numer of degrees is your contact. If its close, it might describe lets say 10 degrees or more. If its far, it might describe 1-4 degrees. For the general direction of travel simplly follow the sound contact with the hydrophone. I say general direction for good reason because the contacts course depends on the angle on bow.
Good hunting!
__________________
|