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Abstract
GPS Surveyed Time-Invariant Ellipsoidal Depths for Safer Marine Navigation
Dr Muneendra Kumar
Consultant
Montgomery Village, MD, USA
Email: munismk@yahoo.com
Dr. George A. Maul
Professor of Oceanography, Florida Institute of Technology, Melbourne
Email: gmaul@fit.edu
Abstract
For safe sailing, two of the most important requirements are to be able to determine the clearance between 1) the sea floor and the keel of the ship and 2) the mainmast and bridges or overhead cables. If these clearances can be measured with respect to a time-invariant zero reference, mariners would have them whenever required. In shallow waters and in harbors, it would enable the captain of a ship to find the clearances accurately and with confidence to avoid grounding or striking overhead obstructions. Combining the GPS surveys and acoustic soundings, highly accurate time-invariant ellipsoid depths of the sea floor can be surveyed in any new area or to fill in gaps independent of the stage of the tide. These depths can be stored in a bathymetric database for future use. Similarly, ellipsoidal heights of overhead bridges and cables from ground surveys using GPS can also be stored.
While underway with GPS positioning, this approach will enable the mariner to recover already surveyed sea floor depths and overhead heights from database(s) in shallow waters and/or entering any harbor, and compute the ship's clearance for safe navigation without regard to the time-variant tides and the ship's draft. Bon voyage to every mariner for every sailing and for all the times!
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