Approach This “Sailing Navigation Hazard” with Care!

Captain John from gives an overview on what to look for when transiting a channel at night and coming across an unfamiliar set of lights.

Imagine that you need to enter an unfamiliar channel just after sunset. You have an injured crew aboard and must get her to a medical facility soon. You proceed with caution from buoy to buoy. But then, out of nowhere, you see a row of blinking yellow lights strung across the channel from bank to bank. There are no alternative channels. Deadly shoals surround you on both sides. What now, skipper?

Sail long enough and you will encounter channel maintenance operations. This includes cable or pipeline laying, dredging operations, and bridge construction or repair.

Here, we will discuss the first of these–cable or pipeline construction across the channel from one side to another. Be aware that underwater pipelines while in the construction phase can cause costly damage. Vessels have had rudders ripped off, keels damaged, props and shafts mangled, and crew injured from impact.

In a non-emergency situations, the wisest move may be to anchor and wait until daylight to pass through if inshore. Or, if offshore approaching landfall and you see a string of flashing lights ahead, heave-to until daybreak.

But, all sailing and powerboat skippers need to know how to navigate through a pipeline area in safety. You may find that you need to access the other side of the pipeline to:

- Bring an injured or sick crew ashore.

- Gain access to safe moorings or anchorages further inshore.

- Take shelter inshore from oncoming heavy weather.

How to Find the Pipeline “Gate” Opening

Look to the Navigation Rules to identify the way pipeline lights and pipeline openings are marked. Annex V–also known as the “Pilot Rules”–applies to all vessels that operate on US Inland waters (all US waters inshore of the Demarcation Lines), and to US vessels operating on Canadian waters of the Great Lakes (as long as there is no conflict with Canadian law). Dredge pipelines must be marked as described below:

Lights Along the Length of the Pipeline

Lights along the length of the pipeline must be yellow and staggered at equal intervals (not more than 10 meters apart if it crosses a navigable channel). Each yellow light will flash 50 to 70 times per minute. Each light must be visible for two miles on a clear, dark light.

Lights that Mark the Opening in a Pipeline

Find the narrow gap in the pipeline that marks an open slot for vessels to pass through in safety. Look for two red, non-blinking lights in a vertical line at each end of the pipeline.

These will be visible all around the horizon for two miles on a clear, dark night. The lower red light on each side will be at the same height as the yellow blinking lights. The higher red light will be a minimum of one meter (3.3 feet) above the lower red light on each side.


Follow these sailing tips for safety when you come across a dredge pipeline at night in a narrow channel or waterway. With this knowledge, you can pass through the pipeline in safety, access the other side of the channel, and keep boat and crew safe and sound—wherever in the world you choose to cruise!

Courtesy of

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