Which Flashing Light Tells You to Enter a River Lock?

which flashing light tells you to enter a river lock

When reviewing for a Boat Ed exam one of the more common questions to pop up asks you which flashing light tells you to enter a river lock.

River locks have strict rules and regulations on who can enter and when they are allowed to enter. Not only that, but river locks also have to consider boat priority, and that commercial vessels will almost always be given more priority than other boats, with the exceptions being emergency and military vessels.

Regardless, much like an intersection on land, you have to understand the traffic lighting system composed of colors green, red, and amber and obey such rules to prevent any untoward accidents near river locks.

Correct Answer

So, which flashing light tells you to enter a river lock?


A flashing green light is the color of the signal light that tells you that you can now enter a river lock. This is the cue where the lockmaster has made sure that it is safe for you to approach and enter the river lock having no more boats or hazards in your path.

River Lock Lights Explained

To get a few things out of the way first don’t be confused when encountering a solid or flashing light. That is because some river locks use fixed lights, but others commonly use flashing lights. They both generally mean the same thing, and what really matters is the color of the signal.

Red Fixed Light

A red fixed light that is not flashing for example means that the lockmaster either isn’t aware of any boats approaching or hasn’t noticed any yet, regardless, this would still mean that you are not allowed to approach the river lock just yet.

Flashing Red Light

A flashing red light on the other hand blatantly tells you to keep away from the river lock and that you should not attempt to enter. As a consequence, you should allot some space for other boats to exit before you ready yourself and start entry on an amber signal.

Amber Light

An amber light means that you are now allowed to approach the river lock but you have to do it safely and in a cautious and controlled manner. Slow and steady is the name of the game and always watch out for potential environmental hazards and the courses of other boats. Much like an intersection on land, always look both ways before crossing.

Amber Light with Green Light

If the amber light is accompanied by green light at the same time, then you are allowed to go towards the river lock at speed but still maintaining control. The extra signal from the green light means that there is no need to be too cautious at this point thus you can speed up if you’d like.

Green Flashing Light

A green flashing light means that this is your cue to enter the river lock. The lockmaster would also make long blasts with his horn after making sure that the path is clear for you to enter.

For exiting a river lock, the same lighting system above is used, however, the difference is that instead of long horn blasts signifying your entry to the river lock, short horn blasts are used to signal your exit.

Why Understanding River Locks is Important

River locks are in some ways similar to the intersections cars pass through. The takeaway here is to patiently wait for your turn, as most river locks cannot allow the two-way movement of boats at the same time.

It is important that you learn the value of how sophisticated and amazing a river lock is not only as a tool for transport but also as an engineering marvel. Being able to travel up and down rivers significantly faster than boats naturally could bring a lot of advantages, with that in mind, a river lock is meant for the public utility and for stimulating the economy, no one person owns it thus you should learn to patiently wait for your turn. Respect the river lock and respect other boats, your turn will come soon enough.

More Boating Education Q&A's Explained


In summary, a flashing green light is a signal that allows you to approach and enter a river lock. Now, this may not necessarily be the case for all river locks as some prefer to use fixed lights, regardless you should do your own research on the river locks that you will most likely be passing through.

There are no shortcuts to becoming an experienced boater other than experiencing things first hand, but this article is just a simple and basic guide on river lock signal lights thus do take heed with a grain of salt.

That said, if ever you’re in a pinch and would like to know about which flashing light tells you to enter a river lock, you can always come back to this article and use it as a guide.

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