Boat Navigation Lights.

Boat Navigation Lights: Understanding the Basics

Written by Chuck Warren
July 15, 2022

Last Updated on July 19, 2022 by Boatsetter Team

For many boaters, the best way to end a beautiful day on the water is to watch the sun slowly drop below the horizon while it lights up the clouds and sky above. Others feel better heading to the dock before the sun goes down, while there is still plenty of light to illuminate the channel markers and other potential dangers.

Besides understanding boat navigation light rules, it is also important to understand:

  • The overall purpose of boat navigation lights
  • How to properly use boat navigation lights
  • What the different colors (red and green) mean

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Red Boat Navigation Light.

How do boat navigation lights work?

Boat navigation lights, or “nav lights,” are the colored marker lights visible on either side of the vessel and at the stern. These lights play essential roles in identifying the ship’s length, direction, and purpose!

The colored marker lights and where to find them go as follows:

  • The boat’s port side is marked with a red light.
  • The starboard side light is green.
  • When looking at the boat’s transom or stern, a white light may be visible.

Keep in mind large boats and ships may use other colors, like yellow.

Next time you’re boating at night, say thanks to your navigation lights. They allow you to see other boaters in the dark and help prevent collisions. But there is much more to boat navigation lights than that.

How to use boat navigation lights

Each of the boat’s navigation lights is only visible for so many degrees of a circle to prevent confusion and accurately identify which side is in view.

By noting which colors are visible on another vessel, boaters can identify which direction the other boat is facing or headed. Knowing a boat’s direction can be especially important when crossing paths with another vessel in the dark.

If you walked around a boat at night while the navigation lights were on, the color visible would change depending on where you stood. When looking at the port side of the boat, the red light would be visible from dead ahead of the vessel to just past the center of the port side or through 112.5 degrees of a circle. Walk to the starboard side, and the green light would be visible from the bow to just past the boat’s center, or another 112.5 degrees.

Stand at the back of the boat, and you will see the white light visible for a total of 135 degrees from one side of the vessel to the other. Add up all three, and you’ll get 360 degrees.

Green & Red Boat Navigation Lights.

Boat navigation light color meanings

If you were on a boat at night and could see nothing but the different colored lights of another vessel ahead of you, you would still know exactly which way that boat was going.

  • If you could only see the red light ahead of you, you would know that you are seeing the other vessel’s port side, or it is crossing in front of you from your right to left.
  • The opposite is true if you saw the other vessel’s green light. You would be looking at the other vessel’s starboard side or watching the boat pass in front of you from left to right.
  • If you see both red and green lights, then the other vessel is coming straight at you if you can see both red and green lights.
  • If you can only see the white light and nothing else, you would look directly at the other boat’s stern as it drives away.
  • Red and white means the boat is driving away from you, crossing from right to left.
  • On the other hand, green and white signal that the vessel is moving away from you, crossing from left to right.

When renting a boat on Boatsetter, make it a habit of checking that navigation lights are working. You should turn on the navigation lights even if the sun is out. It’s the best and safest boating practice.

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