We improved arithmetics of Mercator mapping transform and inverse transform.

By Mercator projection,the geographical coordinates of the ship can be transformed to plane rectangular coordinate,then to the screen coordinate.

In hydrographic sweeping survey,considering that the surveyed route in design project description is a longer route which is composed of two geodetic coordinates,methods of Mercator projection,UTM(Universal Transverse Mercator) projection and Gauss-Kruger projection were adopted to eliminate the direction deviation of sweeping survey,and conform to the conventional way of sweeping survey as well.

In order to solve the problem of chart projection transformation among all projections in shiphandling simulator,using the theory of power series spreading out and the method of trigonometric power series calculating back, a direct and reverse solving algorithm models of meridian arc length, and Gauss projection and Mercator projection transforming algorithm are introduced in this paper.

Method of coordination transformation between Mercator chart and Gauss kilometre map;

This paper analyzes the problem of Sun s high altitude position circle on Mercator chart, curvature radius and centre,thus coming to the conclusions: (1) The method of plotting position line of Sun s high altitude may extend to h ⊙≥87°36′.

In this paper the author examined and argued about the errors in translations of meridianal parts, MP, into Chinese, according to the guiding rules for translations and definitions in navigation, and named the MP in chinese Wei Ju, which means the distance between the equator and a given parallel on a Mercator chart.