What Does A Blue Flashing Light Mean In Boating?
Safe boating requires understanding everything from navigation buoys to the red and green lights common on many vessels. Red and green lights aren't the only ones you may see on the water, though, and some vessels will have flashing blue lights instead. Such a light indicates a law enforcement vessel is actively engaged in a task directly related to law enforcement or public safety. If you see one, exercise caution and allow the boat to proceed with its activity accordingly.
The Code of Federal Regulations states that a law enforcement vessel's flashing blue light must be positioned in such a way that it doesn't limit the visibility of the vessel's navigation lights when the blue light is turned on and blinking. Naturally, no one should ever display a blinking blue light from their vessel if they're not authorized to do so, as they could confuse other boaters on the water. Note that this only applies to flashing blue lights; solid lights on a vessel may serve a different purpose, such as decoration.
There's also the red and yellow light to be aware of
You may also spot vessels displaying flashing red and yellow lights when boating. This indicates a public safety vessel involved in a public safety task. Examples include patrolling regattas and other marine events, assisting disabled vessels, and controlling traffic.
As with the flashing blue light, a public safety vessel's alternating red and yellow light can't interfere with its visibility lights. Technically, this light only identifies the vessel as a public safety vessel, not that it has the right of way or other special privileges, like for land-based police vehicles. Nevertheless, you should still ensure your vessel doesn't disrupt the public safety vessel's activities.
Along with researching your planned routes and keeping the right equipment on your boat at all times, knowing what different buoys, lights, and other such means of nautical communication indicate is critical for safe boating. Adhering to safety rules doesn't just keep you out of legal trouble, but is also key to avoiding harm.