Marine Glossary

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sailings

The method of solving the various problems involving course, distance, difference of latitude, difference of longitude, and departure. The various methods are collectively spoken of as the sailings.

Plane sailing considers the earth as a plane.

Traverse sailing applies the principles of plane sailing to determine the equivalent course and distance made good by a craft following a track consisting of a series of rhumb lines. Any of the sailings which considers the spherical or spheroidal shape of the earth is called spherical sailing.

Middle-latitude sailing is a method of converting departure into difference of longitude, or vice versa, by assuming that such a course is steered at the middle or mean latitude.

Parallel sailing is mid-lat sailing when the course is 090° or 270° true.

Mercator sailing applies when the various elements are considered in their relation on a Mercator chart. Meridian sailing is used when the course is 000° or 180° true.

Rhumb-line sailing is used when a rhumb line is involved.

Great-circle sailing when a great circle track is involved.

Composite sailing is a modification of great circle sailing used when it is desired to limit the highest latitude.

The expression "current sailing" is occasionally used to refer to the process of allowing for current in determining the predicted course made good, or of determining the effect of a current on the direction of motion of a vessel.