This short text describes two particular cases of navigation lights that have come to my attention in recent days. Both are in situations of reduced visibility, or at night. I found the examples interesting because they reveal parts of the navigation lights conventions that are less well known.
Three red lights
You’re near a port and thick fog is severely limiting visibility. On the horizon, you see three red lights superimposed on each other (image right). How should you interpret these lights? What should you recognize?
Anyone familiar with the International Regulations for Preventing Collisions at Sea will know that Rule 28 specifies that three red lights superimposed and visible over the entire horizon indicate a vessel constrained by its draught. This is one possible interpretation of the three lights identified.
If this is the case, then maneuver to avoid the vessel, following the rules prescribed by reduced visibility (Rule 19).
That said, if it is such a vessel, where are its sidelights? And if it’s not
underway, where are its anchor lights? The absence of other lights and the proximity of the harbour should perhaps give a hint that another interpretation is possible. But more than that, it’s also worth remembering the Canadian modifications to the effect that in Canada, ships are forbidden to show the three red lights.
Another interpretation is that these lights are close to a port entry point… and the port signals that entry is forbidden (image above). In this case, the interpretation is that we may be close to an inlet!
The convention in the last paragraph is less well known, but is the responsibility of the International Organization for Aids to Navigation. IALA is responsible for coordinating colors and lights for buoys. The organization is best known for its two global color and buoy systems (Canada is in System B). It does, however, publish a guide to harbor signals. The image above is an extract from the report.
If you’ve ever passed through the Quebec marina, you’ll have seen these lights in action at the entrance to the basin lock. When they’re red, it means that the lock is closed, or that sailboats are leaving the lock. Enter the lock only when the lights are green.
A flickering yellow light
You’re near a Canadian military base and see a ship on the horizon. It displays the usual side lights (you can see its port light), as well as the usual masthead light. In addition, you see a yellow flashing light that goes on and off at about 90 beats per minute. What kind of ship is this?
The image suggests a hovercraft. The Collision regulations also suggest that this is the type of vessel. Hovercraft must have a yellow flashing light visible over the entire horizon. That’s certainly the first thing I’d think of if I saw this situation in practice.
That said, two things should suggest that this is not that type of vessel. First, RIPAM specifies that a yellow flashing light beats at 120 beats per minute (as opposed to 90). Secondly, if we were to see the situation described in practice, we’d see a vessel that moves much more slowly than a hovercraft. Above all, it would be much longer.
In its annual Notices to Mariners, the Canadian Coast Guard publishes a memorandum detailing the navigation lights of Royal Navy submarines. Obviously, these lights are only displayed when they want to be visible … and when they are on the surface. In paragraph 3b), we see that they display a yellow light with a glow of 90 beats per minute.
In short, we’re not dealing with a hovercraft, but a submarine. If you want to avoid torpedoes, maybe it’s best to stay away from them!
So you won’t have to worry about going to sleep!
Both cases are reminders that, although RIPAM is an important reference for identifying night navigation lights, it’s not the only one. It must be interpreted in the light of navigational aids, in this case harbor lights, as well as military conventions (military vessels are not bound by RIPAM) or other sources detailing local conventions.
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