How To Read Marine Charts? Buoys Or Beacons Are Indicated By A Black Dot Below Diamond Shape.

How To Read Marine Charts? Buoys Or Beacons Are Indicated By A Black Dot Below Diamond Shape.

There are many more recreational boats on the water nowadays than there were in times past and they are competing with commercial boating of all types for space. While commercial boaters know how to read maps and so navigate safety, there are many recreational boaters who do not. They endanger their own safety and that of their passengers by lacking this necessary skill.

Marine charts are not just maps that show you where to go. They hold lots of safety secrets such as the depth of water and the position of natural obstacles such as reefs, bridge and power lines and their height and width clearance where applicable. They tell you all about the tides and currents for a particular area and if you can easily locate landmarks that are of use to the boater, or other man-made aids to safe boating such as buoys and markers – especially necessary for boating in channels.

So we know the necessity of being able to read a marine chart; how do we do it? There are so many letters and numbers on it you’d think it was written in code. It has been, but the code is easy to understand.

Take Fl R 4sec 33ft 4M ‘2’ HORN marker, for instance. What does it mean? It’s really simple! Fl means flashing, R = red, 4 sec means it’s flashing red for 4 seconds. 33 ft means it is 33 feet high and can be seen for a distance of 4 miles (4M). It is marked with the number ‘2’ and has a horn to blast when visibility is bad.

These letters and numbers may vary. The flashing light could be green (G) the height could be, say 10ft and so on.

There are international shipping rules and national shipping rules that often vary from country to country, so if you see a chart with COLREG’S demarcation line written on it (usually with an arrow) that is the invisible line – usually between two markers – where the international rules end and the national rules begin.

Lights on marine charts are usually indicated by what looks like an exclamation mark on a lean. The black dot at the base is the light. Or it could be a black dot in the middle of a larger, colored dot. Additions to the light mark could be ‘aero’ to indicate that the light is used to guide planes, but can also be used by boats; a black ‘frill’ around the dot indicated that there are rocks piled up around the base of the light and ‘bn’ indicates a beacon.

Buoys or beacons are indicated by a black dot below a diamond shape. If the diamonds are banded with red and green it means they mark where two channels join. Black and white means there are commercial fishing nets in that area, while solid white indicates safe anchorage. Orange and white indicates a restricted area.

Once you start studying up on how to read a marine chart, you’ll find that it is quite logical and that’s what makes it so easy.