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rhumb line

a curve on the surface of a sphere that cuts all meridians at the same angle. It is the path taken by a vessel or aircraft that maintains a constant compass direction.
Also called loxodrome, rhumb.
1660-70 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for rhumb line
  • Under sail there is no such thing as a rhumb line or a great circle track from departure to destination.
  • If they are sailing on the great circle track, they use a rhumb line or composite track for comparison.
British Dictionary definitions for rhumb line

rhumb line

an imaginary line on the surface of a sphere, such as the earth, that intersects all meridians at the same angle
the course navigated by a vessel or aircraft that maintains a uniform compass heading
Often shortened to rhumb
Word Origin
C16: from Old Spanish rumbo, apparently from Middle Dutch ruum space, ship's hold, but also influenced by Latin rhombus
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Encyclopedia Article for rhumb line


curve cutting the meridians of a sphere at a constant nonright angle. Thus, it may be seen as the path of a ship sailing always oblique to the meridian and directed always to the same point of the compass. Pedro Nunes, who first conceived the curve (1550), mistakenly believed it to be the shortest path joining two points on a sphere (see great circle route). Any ship following such a course would, because of convergence of meridians on the poles, travel around the Earth on a spiral that approaches one of the poles as a limit. On a Mercator projection such a line (rhumb line) would be straight. Rhumb lines are used to simplify small-scale charting

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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