Article » How To Read A Nautical Chart

In order to navigate safely, any good boat owner needs to carry nautical charts with them as they negotiate life at sea. Before you set off on that adventure of a lifetime, it’s essential to learn the ins and outs of nautical charts.

Learn To Read Nautical Charts

Once you learn how to read these charts, you’ll automatically be able to read essential navigation symbols including channels, water depths, the positions of buoys, and information on any obstacles or landmarks to avoid so you can negotiate a route safely.

The top of the chart will tell you the area of water being covered and the scale of the map.  Some nautical charts are measured in fathoms - if you have little experience with this unit of measurement, one fathom is equivalent to six feet.  Each individual waterway will have been carefully scrutinised on the maps – be sure to refer to the reference anchorage areas and the caution notes that are all designed to make your journey run as smoothly as possible.

Try to take a variety of charts and maps with you before you travel – different nautical charts can give you an in-depth understanding of a passage of water – some will be on a larger scale, some on a smaller scale. You can also purchase specific harbour charts,  coastal charts and even charts for navigating inland waterways – so try and purchase a wide selection of charts to prepare yourself adequately for a boating trip.

These charts effectively pinpoint your position using lines of longitude and latitude.  For those trying to read the latitude scale, read the lines running down the chart vertically from North to South. The longitude lines run from East to West horizontally along the chart. One of the most in depth aspects of reading a nautical chart is learning how to read fathom curves and soundings. A measure of depth, soundings are represented by the numbers on a chart. Fathom curves are similar to contour lines on general maps, and represent a land profile of the bottom of the body of water.

Finally, you’ll need to learn how to read the compass rose. Most nautical charts have at least one of these – and they are used as a means of measuring direction using a magnetic or true bearing. The number in the centre of the compass rose can tell you the variation between true and magnetic north for the area covered.