The shortest distance between two points on the surface of a sphere, formed by the intersection of the sphere with a plane passing through its center. Great circle routes save distance on long ocean voyages but require frequent course changes.
Category: Navigation & Seamanship
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DraftThe vertical distance between the waterline and the lowest point of a vessel's hull, indicating how deep the ship sits in the water.DraughtThe British English spelling of draft, referring to the depth of water a vessel draws.ECDISElectronic Chart Display and Information System, a computer-based navigation system that complies with IMO regulations and can be used as an alternative to paper nautical charts.HeadingThe direction in which a vessel's bow is pointed at any given moment, measured in degrees from north.KnotA unit of speed equal to one nautical mile per hour, approximately 1.852 kilometres per hour or 1.151 miles per hour.LatitudeThe angular distance of a point north or south of the equator, measured in degrees, minutes, and seconds from 0 degrees at the equator to 90 degrees at the poles.
Back to DictionaryEntry updated May 2026