Red and green lights on boats

Navigation lights help you and other boaters determine which is the give-way vessel when encountering each other at night. These lights must be displayed from sunset to sunrise and during periods of restricted visibility, such as fog. There are four common navigation lights.

• Sidelights: These red and green lights are called sidelights (also called combination lights) because they are visible to another vessel approaching from the side or head-on. The red light indicates a vessel’s port (left) side; the green indicates a vessel’s starboard (right) side.
• Sternlight: This white light is seen only from behind or nearly behind the vessel.
• Masthead Light: This white light shines forward and to both sides and is required on all power-driven vessels. (On power-driven vessels less than 39.4 feet in length, the masthead light and sternlight may be combined into an all-round white light; power-driven vessels 39.4 feet in length or longer must have a separate masthead light.) A masthead light must be displayed by all vessels when under engine power. The absence of this light indicates a sailing vessel because sailboats under sail display only sidelights and a sternlight.
• All-Round White Light: On power-driven vessels less than 39.4 feet in length, this light may be used to combine a masthead light and sternlight into a single white light that can be seen by other vessels from any direction. This light serves as an anchor light when sidelights are extinguished.

Boating can offer a safe activity outdoors and allows the opportunity for fresh air and much-needed sunlight. Though the best way to ensure a good time for everyone is knowing and following the rules of boating safety. 

The red and green lights are part of boating safety. They are able to be seen from a distance and help an observer be able to tell which side (port or starboard) they are looking at. This can be important, so they know which direction the boat is headed. Red and green lights, called sidelights (or combination lights), are just one part of boating safety. 

Observing boating safety is one of the best ways to ensure that everyone has not just a good time on the lake (or ocean) but also reduce the risks of injury from collisions on the water. Lights of different colors are used to be able to signal not only the port and starboard side of a boat but also the stern and the bow of a boat. 

Boating Terms

There are a few different terms that are absolutely “need to know” when it comes to boating. Boating doesn’t use terms such as left and right or front and back, so getting to know these terms is a first step in knowing what the colors of the lights on each part of a boat mean. According to wavesboatclub.com, these terms are

These terms are:

• Port
• Starboard
• Bow
• Stern
• Fore
• Aft
• Underway

All directions refer to standing near the rear of the boat and looking forward. By using this universal orientation, it makes it easier to be sure you are using the correct term when describing a boat or ship. No matter the size of the watercraft, the terms are the same, and knowing them will allow you to be able to understand the rules of boating safety. 

Port

The port of a boat refers to the left side of the boat. This is where the red light will be, to indicate to an onlooker that it is the left side of the vessel. If an onlooker can ONLY see the red light, this would indicate that they are looking at the port or left side of your vessel. 

Starboard

Starboard refers to the right side of a boat. Starboard is where the green light would be. Seeing only the green light would indicate to onlookers that they are looking at the right side of the boat and, most likely, you are traveling in that direction. 

Bow

The bow is the front of the boat. On the old pirate ships, this is where you would see the figurehead or figure that guides the way in front of the ship. This is also where the masthead light would be. This must be on all motor-driven boats and not only helps the captain see where he is going, but also indicates, in the dark, where the front of a boat or ship is. 

Stern

The stern refers to the back of the boat. This is where the engine or motor would be (depending on the size of the boat). This is where a stern light would be. This is seen only (or almost only) from the rear of the boat. Seen in combination with the red and or green sidelights helps an onlooker tell the direction a boat or ship is heading. 

The stern is where the engine or motor is kept, so the stern light can also be used if some engine work needs to be done in the middle of the night. Major repairs would, most likely, require a better light source, though. 

Fore

Fore or forward refers to moving towards the front of the boat. Thus if you are moving in a Fore direction, this would mean you are moving towards the front of the boat or from the stern to the bow of the boat. 

Aft

Aft refers to the reverse as fore. Moving towards the aft of a boat refers to moving to the back of the boat or from the bow to the stern. 

Underway

Underway is a reference to the boat being in motion. While this may usually refer to motor-driven propulsion, this can also refer to the momentum created by wind in a sailboat as well. 

The Purpose of the Lights

While it may seem pointless to a smaller vessel that only goes out on sunny days to enjoy a boat ride on the lake to have the lights, there is a deeper purpose to the lights and the different colors. Boats and ships have to adhere to the same rules when it comes to water travel, just as cars and big rigs must adhere to the same laws on the road. 

Ships and larger boats may spend time on the water and night, and this is where the lights make the biggest difference. While much transportation is still done by ship to other countries, what comes to mind primarily is fishing vessels. Whether you are thinking of the big crab boats from Deadliest Catch or a couple of guys just doing some night fishing, the lights matter. 

Out on a big lake, such as the Great Lakes in the midwest or in the ocean, if you get far enough out onto the water, your only source of natural light at night is the moon and stars. If it is a cloudy night, even that small amount of light can disappear, leaving you and everyone around you, in near-total darkness. 

The use of lights, especially colored ones, can allow one craft to see the other from a distance and prevent a collision. This can save not just the cost of boat repairs, but save lives as well. A collision that far out can turn into a deadly scenario quickly since the Coast Guard cannot be easily available, especially in the event of a ship sinking. 

How the Lights Help Determine Orientation and Direction

Since the lights are color coordinated and are direction-specific, a vessel from a distance can tell if they are looking at the port or starboard sides of the boat or ship. If they can see the masthead light and red light, this tells them they are looking at the port (or left side). The masthead light will be much higher up than the stern light, so placement matters as much as color. 

Just by knowing what lights mean what, a vessel from a distance can tell more than what side they see and if you are in motion. Since the masthead light must be in use if you are moving, then seeing the masthead light also tells the vessel you are moving. If the masthead light is off, then most likely, you are anchored. 

This can be especially useful in the event of a fire onboard a distant vessel as well. You would be able to steer clear of the boat as well, but still, be able to pick up people who have jumped off or “abandoned ship” to aid in the case of an emergency or a sinking ship. 

While the masthead and stern lights are both just general white lights, it is their placement that allows for the determination of orientation. Masthead lights are, as they sound, on the mast. This means they are more in the air and easier to spot from a distance. While stern lights are lower and seen primarily from the back.

Do you have to have red and green lights on a boat?

What do the colored lights on a boat mean?