Theory of preparation of Navigational Chart

Navigational charts are essential tools for safe and efficient navigation. They provide mariners with information about the seafloor, surrounding land, and navigational hazards. Navigational charts are also used for a variety of other purposes, such as coastal engineering, marine research, and maritime planning.

The preparation of navigational charts is a complex process that involves the collection, processing, and analysis of a wide variety of data. The goal of chart preparation is to create a depiction of the seafloor and surrounding land that is accurate, reliable, and easy to use for navigation.

1.The first step in preparing a navigational chart is to collect data on the seafloor and surrounding land. This data is collected using a variety of hydrographic survey methods, such as multibeam sonar, side scan sonar, and echo sounding. Hydrographic surveys also collect data on the position of underwater features, such as shipwrecks and pipelines.

2. Once the data has been collected, it is processed and analyzed using specialized software. This software is used to create a digital elevation model (DEM) of the seafloor. The DEM is a three-dimensional representation of the seafloor that shows its depth and relief.

3. The DEM is then used to create a contour map of the seafloor. The contour map shows the depth of the water at different locations. Contour maps are an important tool for navigation because they allow mariners to see the shape of the seabed and to identify underwater hazards.

In addition to the contour map, navigational charts also include a variety of other information, such as:

• The position of navigational aids, such as lighthouses and buoys
• The location of restricted areas, such as shipping lanes and military zones
• The names of geographical features, such as islands and reefs
• Tides and currents
• Magnetic variation
• Meteorological information

Navigational charts are typically prepared by government agencies, such as the National Oceanic and Atmospheric Administration (NOAA) in the United States. However, there are also a number of private companies that produce navigational charts.

Once the navigational chart has been created, it is published and made available to mariners. Navigational charts are available in a variety of formats, including paper charts, electronic charts, and online charts.

Navigational charts are essential for safe and efficient navigation. They provide mariners with the information they need to avoid hazards and to navigate accurately. Navigational charts are also used for a variety of other purposes, such as coastal engineering, marine research, and maritime planning.

Here are some additional details about the theory of preparation of navigational charts:

• Projection: Navigational charts use a variety of projections to represent the curved surface of the Earth on a flat plane. The most common projection used for navigational charts is the Mercator projection. The Mercator projection is a conformal projection, which means that it preserves the shape of objects on the chart. However, the Mercator projection distorts the size of objects, particularly near the poles.
• Datum: Navigational charts are referenced to a datum, which is a horizontal and vertical reference system. The most common datum used for navigational charts is the World Geodetic System 1984 (WGS 84). WGS 84 is a global datum that is used by GPS receivers.
• Symbology: Navigational charts use a variety of symbols to represent different features, such as navigational aids, underwater hazards, and geographical features. The symbols used on navigational charts are standardized so that mariners can easily understand them.

The preparation of navigational charts is a complex and challenging task. However, it is an essential task for ensuring the safety of mariners and the efficient operation of maritime commerce.