Navigation and Seamanship

1.4.1. Introduction

                                                                                   

            The nautical chart is one of the mariners’ oldest and most widely used navigational aids. A Nautical chart or Navigational Chart is a graphic (pictorial) representation of a navigable portion of the earth’s surface, on a plane surface. It has been specially designed for the use of navigation. It is used to work upon, not merely to be looked at, and should readily permit the graphic solution of navigational problems such as distance, direction and determination of position in terms of latitude and longitude. It shows information such as coastline, harbour, depth of water, nature of bottom, channels, land marks, dangers and other information of interest to navigation.

When the ship is being navigated along or near the coast, the art of fixing the ship’s position graphically, laying a safe course to destination and checking ship’s positon whilst on, the course to ensure the vessel’s safe arrival is called “Chart work”.

As the safety of the ship depends upon the accuracy of the navigational chart, utmost care is taken in its construction and upkeep. It is drawn precisely giving full details of all the information required by the navigator.

The chart must naturally cover more area of the sea, as compared to the land, and should highlight the information that a mariner requires to navigate his ship safely from one position to another, that is to say the chart must show clearly the depth of water, nature of the bottom, details of coastline and off lying dangers and the various navigational aids e.g. light houses, prominent land marks, light vessels and radio beacons.

The term chart is derived from the Greek word –chartes- the meaning is a leaf of papyrus. The Greek used sailing directions several hundred years before the birth of Christ. Gerardus Mercator, the Flemish cartographer who produced a world chart constructed on the basis of the projection which bears his name, is the father of modern cartography.