If your wire (set at a certain depth by a process of weights and buoys) encountered an obstruction, it might grow to be taut and kind a "V," revealing the depth and place of submerged rocks and other obstructions. These charts involve historic functions, for instance LORAN-C traces. Hydrographic survey https://holdenxpcox.blogdal.com/32886404/the-definitive-guide-to-hydrographic-survey-in-dhaka