Navigation and Seamanship (1+1)

1.4.4. Classification of Nautical Charts

World charts: These charts are very small scale covering the large area of the world showing ocean routes, magnetic variations, telegraph cables, ocean currents etc.

Ocean charts : There charts are prepared on a very small scale, covering large portions of the earth eg. Indian ocean, North Atlantic ocean. On such charts only the outstanding coastal features and important ports etc. are shown. Since these charts show little detail these charts are unsuitable for coastal navigation. These charts are used for planning and executing long voyages across the oceans. The scale of these charts ranges from 1 : 6,00,000 to 1 : 14,000,000.

Coastal charts : These charts are of medium scale and cover only a portion or a part of the coast. They show all the aids to navigation like lighthouses, Radio station, important navigation marks, off lying rocks, dangers etc. These charts are used when the ship is being navigated along the coast. Coast charts thus highlight the features on and along the coast and the adjoining portions of the sea. The scale of these charts ranges from 1:50,000 to 1:6,00,000.

Eg. Manapad to Sethukari

Kolachal to Manapad

Mumbai to Cape Comerin

Plan charts : These charts are drawn on a very large scale and each plan covers only a small area eg. Tuticorin Harbour, Vepalodai anchorage etc. They contain all the information required when navigating a ship in side the harbour and other congested and enclosed waters. Every possible information of use to navigator is shown in great detail. The scale of these plan charts enables the mariner to plot his position with great accuracy and thus avoid the dangers, which are frequent in ports and harbours. The chart with a scale ranging from 1 : 2,500 to 1 : 50,000.