Early hydrographic surveys consisted of depths measured by sounding pole and hand guide line, with positions based on 3-stage sextant fixes to mapped reference points. Guide traces ended up ropes, or lines, with depth markings and lead weights hooked up. Hydrography is collected under regulations which vary dependant upon the https://hydrographicsurvey13086.like-blogs.com/32288603/hydrographic-survey-in-dhaka-no-further-a-mystery