GREAT CIRCLE SAILING - CALCULATION OF INTERMEDIATE POSITIONS

摘要

This paper deals with the realization of the great circle navigation. In practice, the main problem occurs because the great circle is a curve on the Mercator navigation chart, which has to be broken down into a number of smaller rhumb line parts. Besides computer programs, the simplest way of realization of the great circle navigation is by using the Gnomonic chart as the great circle is a straight line on this chart. Conventional numerical and tabular methods based on spherical trigonometry are quite complicated and time consuming. In order to simplify the way of computing intermediate positions along the great circle, this paper suggests the use of the Latitude Equation of the Mid-longitude and appropriate tables based on this method. Also, using spherical trigonometry, the paper presents a way of obtaining the Latitude Equation of the Mid-longitude. Originally, the Latitude Equation of the Mid-longitude is derived without the use of spherical trigonometry.