Time-Invariant Sea-Floor Depths Using the Ellipsoid As Zero-Reference Surface Sep 1, 2005 By: Muneendra Kumar, George A. Maul

A GPS survey combined with acoustic soundings can determine highly accurate sea-floor depths. Using the ellipsoid as the zero-reference surface then allows navigators, while underway, to determine both keel and overhead obstruction clearance independent of the stage of the tide and the draft of the ship and freeboard.

To All the Ships at Sea Jul 1, 2004 By: Jean Marechal

EGNOS serves as part of a system to track ocean-going vessels automatically over a large region.