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How to Read a Nautical Chart - Part 1


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Read the General Information Block
Close-up of nautical map and compass in ships map room
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To pilot your boat safely, you should carry paper nautical charts on your boat. Becoming familiar with nautical chart basics will form a foundation for knowing how to read the chart symbols that show channels, water depth, buoys and lights, landmarks, obstructions, and other important information that will ensure safe passage.

The general information block of the chart shows the chart title, usually the name of the navigable water in the covered area (Tampa Bay), the type of projection and the unit of measurement (1:40,000, Soundings in Feet). If the unit of measurement is fathoms, one fathom equals six feet.

The notes contained in the general information block give the meaning of abbreviations used on the chart, special caution notes, and reference anchorage areas. Reading these will provide important information about the waterways you navigate not found elsewhere on the chart.

Having a variety of charts will serve you well. Depending upon the location you will be navigating, different charts will be necessary because they are produced in different scales, or ratios (type of projection). Sailing charts are used for open ocean navigation, but unless you intend to cruise long distances, this chart typically will not be essential. General charts are used for coastal navigation in sight of land. Coastal charts zoom in on one particular portion of a larger area and are used for navigating bays, harbors, or inland waterways. Harbor charts are used in harbors, anchorages, and small waterways. Small craft charts (shown) are special editions of conventional charts printed on lighter paper so they can be folded and stowed on your vessel.

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