Radar Beacons

Every time you turn around there is another "Aid to Navigation" (ATON) on the water to help you find your way. We're all familiar with dayboards and buoys. They are the most common ATONs and we find them everywhere. Let's talk about a few that aren't so common.

You can receive signals from transmitters known as Radar Beacons. These aids to navigation transmit signals on the marine radar band. The signals from such transmitters produce a distinctive image on your radar screen. Thus, not only does your radar exhibit the presence of a "target," it actually identifies specific targets.

Radar Beacons are mounted in fixed locations and are triggered by the presence of a radar signal from any nearby vessel. Once the Radar Beacon senses that a vessel with radar capability is in the vicinity, it's radar transponder begins transmitting. The signal is unique to that specific aid to navigation.

There are two kinds of Radar Beacons. The first type, called "RACONS," will provide both range and bearing information. When a vessel receives a RACON signal, it is usually displayed on your radar screen in Morse code. A series of dots and dashes is used to represent a specific point on your navigation chart.

The second type of Radar beacon is called a "RAMARK." These aids to navigation provide only "bearing" information. They will appear on your radar screen as a dashed line between the center of the screen and the location of the transponder that is transmitting the signal. In this case, you can determine the direction in which the RAMARK lies on your chart, but not it's distance from your vessel.

In either case, the RACON or the RAMARK can be extremely helpful in fog or other restricted visibility. You will usually find them in busy waterways where there is a lot of commercial shipping traffic. You can find them on your navigation chart by looking for RACON or RAMARK in the description of an aid to navigation.

We are all familiar with the role of the lighthouse in helping mariners find their way. A lighthouse can exhibit a light in any part of its 360-degree arc of visibility. Some lighthouses are partially obscured (no light showing for part of the 360-degrees possible) when showing a light in all directions is not prudent. Another option regarding a lighthouse is what we call "colored" sectors.

A colored sector of a lighthouse shows a color (other than white) in part of its 360-degree area. In cases of danger, red is a common color. Where rocks, shoals, or some other hazard to mariners is present, the light from a lighthouse may show red in that area and white elsewhere. The "red sector," as it is called, is shown on the your chart. Once you examine the chart, you can see the hazard that the red sector is warning you about.

Colored sectors may be used to indicate things other than danger. Examination of your navigation chart will reveal what a colored sector is there for. The color of the sector, along with the bearing lines at its limits, will be illustrated on your chart adjacent to the lighthouse.

Your navigation chart is a valuable tool. The closer you look, the more it will tell you!

Until next time, I wish you clear skies, fair winds, and calm seas!