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post #13 of Old 03-05-2019
Damon Gannon
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Re: Lateral Marks

Originally Posted by davidpm View Post

If I'm in the fog in the LIS and see a Red mark unless I consult the chart I have no idea if I should take it on my left or right.
This is exactly the point! In unfamiliar waters, you will never know on which side to pass a mark without consulting a chart AND understanding the system by which AToNs are arranged and identified (the symbol legend for nautical charts is called "Chart no. 1" and is available here: Simply following the marks without consulting a chart is a good way to put a hole in your boat. Is that next buoy ahead marking the channel that I'm in now or is it for an another channel, which may be on the other side of a shoal? There are only two ways to find out: consult a chart or take the risk of running your boat up on a rock.

Your friend is correct. All red and green marks are considered lateral marks (I'm assuming he meant just red and green marks and not safe water marks like red-and-white sea buoys or range marks, or hazard marks such as day beacons or lights) and the series of marks along the northern (red marks) and southern (green marks) shore of Long Island are meant to be treated like a wide channel "returning" towards the Throgs Neck.

Lateral marks may be placed near hazards but they are actually marking the lateral extent of safe water. If you don't know which side to pass on, you don't know where the safe water is. In areas like the coast of Connecticut where there are numerous ledges and many intersecting channels, it is nearly impossible to interpret which marks to follow without looking at a chart. You can tell if a lateral mark is for the Long Island sound "channel" or a smaller bay off of Long Island Sound by looking at a chart and paying attention to the numbers on the marks. Lateral marks are numbered consecutively, ascending as you progress from offshore to inshore. Greens are always odd and reds are even. So if you just passed R "2" and are now approaching R "34", you are going from one set of marks marking one channel to another set of marks delineating a different channel (or you just took a huge shortcut that will likely put you on the rocks). The intersection of the two channels may be safe or there may be a hazard present. You can't tell unless you look at a chart. The numbers on the marks are like street addresses, showing you exactly where you are (if you have looked at a chart). At night, the flashing lights serve the same purpose as the numbers during the day (the chart will say something like "Fl R 4s" which means there is a red light that flashes once every 4 seconds. Without looking at a chart, you wouldn't know what any of those flashing lights are).

A previous commenter posted about "red-right-clockwise" around a land mass; this doesn't apply to Long Island Sound. That is for the ICW. ICW marks are distinguished by the gold square (red marks) or gold triangle (green marks) at their center. Unless you see that gold shape in the center of the mark, then "red right return" still applies. Oftentimes, you can't tell whether you are departing or returning for the purposes of the AToNs unless you consult a chart.

In confined waters, the intersection of two channels is usually marked by a green-over-red or red-over-green mark; the top color marks the "preferred" route (usually the larger, deeper channel). Instead of a number, these Green-Red and Red-Green marks are usually identified by a 2-letter code that signifies local landmarks or features (e.g., "MM" for the intersection of the channels for Milton Harbor and Mamaroneck Harbor or "HL" for Hicks Ledge).

Sorry for belaboring this but if you are navigating in unfamiliar waters without consulting a chart (either an old fashioned paper one or an electronic chart), you are operating negligently. And a final note about using electronic charts: make sure you zoom-in to see the finest details. When zoomed-out, some AToNs and hazards may not be displayed on the chart (just ask the professional navigator who plowed the Vestas Wind yacht into a reef in the Indian Ocean during the Volvo Ocean Race).
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