Early hydrographic surveys consisted of depths calculated by sounding pole and hand lead line, with positions determined by a few-point sextant fixes to mapped reference points. Lead traces had been ropes, or lines, with depth markings and direct weights hooked up. This issue was solved applying multi-beam sounders that captured https://hydrographicsurveyinbangl70134.dreamyblogs.com/32676620/new-step-by-step-map-for-hydrographic-survey