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Is green on port or starboard?

Welcome aboard! As an experienced sailor, I know there can be a lot of confusion surrounding nautical terms like port, starboard, red and green. In this comprehensive guide, I’ll clarify exactly what side green refers to on a ship to help you navigate confidently.

The Meaning of Port and Starboard

First, let’s define port and starboard. These are nautical terms used to indicate the left and right sides of a ship, respectively:

  • Port = left side of ship, facing forward
  • Starboard = right side of ship, facing forward

It’s easy to remember that port and left both have four letters. Starboard and right both have more letters.

Where Green is Located

So where does green come in? Here’s a quick summary:

  • Green light is located on the starboard (right) side of the ship
  • Red light is located on the port (left) side of the ship

These colored navigation lights help other vessels determine what direction your ship is headed and whether they need to yield to you. The red and green side lights are required to be displayed from sunset to sunrise.

Remembering Port and Starboard

To help remember which color associates with each side, here are some memory aids:

  • “Port and left both have four letters.”
  • “Red wine is usually served on the port (left) side of the dinner table.”
  • “Starboard and green both start with ‘S’.”

More on Navigation Lights

Let’s get into some more detail on navigation lights and their meaning:

Light Color Side of Vessel Meaning
Green Starboard Indicates starboard side of vessel
Red Port Indicates port side of vessel
White Fore Located at front of vessel, indicates direction of travel
White Stern Located at rear of vessel

So in summary, green lights are always located on the starboard side, while red lights are always on the port side. This helps other vessels understand your orientation and direction of travel at night.

Examples of Green Starboard Light in Use

When you’re navigating at night, keep an eye out for these green and red light placements on vessels:

  • If you see a ship’s green light, you know it’s headed your starboard (right) side.
  • If you only see a red light, the vessel is headed your port (left) side.
  • If you see both a red and green light, the vessel is headed directly toward you.

Understanding the meaning behind navigation lights helps avoid collisions in low visibility. Here are some specific examples of green starboard light in use:

Passing Port-to-Port

When two power-driven vessels are passing port-to-port, the green starboard light of each vessel will be visible to the other. This indicates they are safely passing one another.

Overtaking Another Vessel

When a ship is overtaking another vessel from astern, the front ship will see the green starboard light of the rear vessel as it approaches. The rear vessel will see both the red port and white stern lights of the front ship.

Towing a Vessel

When towing another vessel, the green starboard light indicates you are attached and headed in the same direction. It’s important the towed vessel also displays the proper navigation lights.

As you can see, correctly using and interpreting green starboard lights prevents accidents and confusion at night.

Proper Display of Navigation Lights

For navigation lights to be effective, they must be properly sized and displayed according to maritime regulations. Here are some key requirements:

  • Lights should be visible from 2 nautical miles away (3.7 km).
  • Red and green sidelights should be visible 112.5 degrees from dead ahead to 22.5 degrees abaft the beam.
  • Lights should be spaced at least 1 meter apart, with the green light on the starboard side.
  • Lights should project an unbroken light over the required arc of visibility.
  • No other lights should obstruct or impair the visibility of required lights.

It’s the responsibility of the captain to ensure all navigation lights adhere to regulations and are displayed properly. This optimizes their visibility and effectiveness.

Daytime Identification of Port and Starboard

While running lights are only required at night, it’s important to be able to identify a vessel’s orientation day or night. Some ways to determine port and starboard during daytime:

  • Masthead lights – Small lights at the top of masts can indicate direction.
  • Bridge location – The bridge is often situated on a ship’s starboard side.
  • Cargo loading – Cargo is often loaded from a ship’s port side.
  • Ship name – Vessel names are often visible on the port and starboard bow.
  • Anchor – Having the anchor hanging off the starboard side can indicate direction.

With experience, identifying starboard and port by day becomes second nature. But when in doubt, consult the running lights at night.

Special Uses of Green Light

While green lights are normally used to indicate starboard, there are some special cases where green carries other meeting:

Dredging and Underwater Operations

On vessels engaged in dredging, laying cable or other underwater operations, an all-around green light indicates the obstruction and limited maneuverability.

Military Convoy

Naval and coast guard vessels may display two all-around green lights when towing a submarine or military convoy.

Medical Transport

Ships declared as medical transports may illuminate one all-around green light to indicate protection under the Geneva Convention.

So while green usually means starboard, it can also signal special circumstances when displayed all-around.

Remembering Green Means Starboard

To recap, here are some tips to help you remember that green indicates a vessel’s starboard side:

  • Memorize “PORT left, STARBOARD right”.
  • Associate green’s color with the green leaves of a star.
  • Think “Green for Go” on the right side.
  • Imagine a green traffic light indicating you may pass on the right.
  • Use mnemonic phrases like “you STARBOARD turn right”.

With practice, remembering where green is located becomes second nature. Knowing proper light configurations can prevent accidents and confusion when navigating at night.

I hope this guide has shed light on how green indicates a vessel’s starboard side. Smooth sailing ahead!


In summary, green lights are always located on a vessel’s starboard (right) side, while red lights are on the port (left) side. Memorizing phrases like “PORT left, STARBOARD right” can help you recall where green is positioned. Knowing the meaning and regulations for navigation lights is crucial for safe travels on the water. With this knowledge, you can confidently determine where green is located and navigate with ease. Bon voyage!