This Is a Description of Nautical Charts

This Is a Description of Nautical Charts

Navigating by nautical charts is essential for mariners. Your navigation to your destination is improved and accidents are prevented if you properly use a chart. It allows you to notice obstacles you might not otherwise notice if you refer to the chart frequently. Obstacles, such as rocks and sandbars, can cause your boat to stop in its wake and hurt you:

  • you
  • your boat
  • the environment

Terminologies, Abbreviations, and Symbols

Chart 1 contains symbols, abbreviations, and terms.

The Canadian Hydrographic Service (CHS) nautical chart chart 239 Symbols, Abbreviations, and Terms on Charts is a handy resource that will help you interpret it. This publication is essential to carry at sea after a nautical chart.

Below is a chart summarized by the CHS of a list of symbols, abbreviations, and terms found on navigation charts. Our charts contain hundreds of these abbreviations and symbols. Based on international standards, our charts can be used anywhere in the world.

Title Block

Examples of graph titles.

First and foremost, you should pay attention to the title block of a nautical chart. Often, this aspect of a chart is overlooked.

Regional Identification

Regional designations in title blocks indicate the general geographic area covered by the chart.

Main Title

The title block for the chart identifies a specific geographical area.

Scale Identification

As an example, 1:15 000 means that 1 unit on the chart is equal to 15000 units on the earth. Below are some examples of charts using different scales and types.

  • Harbour charts are:
    • large scale, 1:2 001 to 1:20 000
    • In harbours and areas of the ocean with shoals, the vessel is used to navigate
  • A method chart consists of:
    • 1:20 001 to 1:50 000
    • This technique can be used to study coasts in detail
  • Coastal charts are:
    • 1:50 001 to 1:150 000
    • used in fisheries charts
    • As it provided continuous and extensive coastal coverage, landfall sightings were possible
  • General charts:
    • are 1:150 001 to 1:500 000
    • Charts used in fishing
    • Landfall can be seen inshore when the coverage offshore is more extensive than is necessary
  • Sailing charts are:
    • 1:500 001 and smaller
    • Having no sight of land while offshore

British Admiralty Nautical Chart 8192: Port Approach Guide Conakry

Identification of the Projection

Projection involves projecting curved objects (like the earth) onto flat sheets of paper (the chart).

Mercator projection is typically used in nautical charts. By flattening, distortions of shape and direction are virtually eliminated.

An Explanation in Depth

The note on the chart indicates the units in which depths are measured. Foot and fathom are used on charts (1 fathom equals 6 feet) or metres and centimetres are used for metres.

Canada will at some point display water depths in metres on all charts.

Illustration of depths.

Elevations Note

Describes the datum used when measuring structure heights and cables’ clearances.

Detailed information about clearance requirements is provided in the note.

Horizontal Datum

Example of horizontal chart.

Objects on the surface of the Earth are positioned using this data. A chart, symbol, abbreviation, and term used in the charts is listed in Chart 1.

Sources Are Categorized According To Their Characteristics

In the classification diagram, indicate where the data came from and how old it is by indicating its source.

Notes on Symbols

Please note that there is a symbol reference note at the end of the title block. This section contains the symbols and abbreviations used in Chart 1.