Navigation and Seamanship

1.1.3.6. Satellite Navigation

1.1.3.6. Position and Direction

                                                

The above methods are giving solutions to the following 3 basic problems of any navigator at sea,

1. How to determine the position of a vessel?
2. How to determine the direction of vessel’s movement?
3. How to determine distance that covered by a vessel?

Position:         Of the above three problems, the most basic is that of locating the position of the vessel at sea. Mariner cannot direct the movements of his vessel with accuracy, safety and efficiency without fixing his position frequently. The term position refers to any identifiable location on the earth or a point within a man-made system of artificial coordinates.

Direction:        Direction is the knowledge of the spatial relationship between two positions. The direction from one to another that makes it possible for a navigator to lay a course from where he is to where he wants to go, and then proceed to that destination. Direction is the orientation of an imaginary line joining one point to another without regard to the distance between them. Direction is measured in angular units, degree of arc from a reference using a polar coordinate system. The usual reference direction is True North or Geographic North. The subdivision of a degree may be either minutes and seconds (1° =60’;1’=60”), or decimal fractions.