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What is a Day Marker? – Reading Markers & Buoys

Written by J. Harvey / Fact checked by S. Numbers

what is a day marker

You need to pay attention to the navigational markers you see when boating, like how you pay attention to the road signs. You need to know many navigational signs, but this article will answer the question: What is a day marker?

A day marker is a navigational sign that aids a boater during daylight hours and is unlit. Its shape can be either a triangle, square, or rectangle, and the color can be red, green, orange, yellow, or black.

Day Markers: Shapes and Colors

A signboard is an essential tool that helps humanity reach miles. It conveys information to help travelers reach their destinations safely.

There are many navigational aids you need to understand when you venture into boating. But his article mainly focuses on ocean day markers or sign boards that are attached to a day beacon.

1 – Green Square Daymark


You will typically see a green square-shaped daymark at water channels. This channel marker usually bears an odd number. If the number increases, it means that the boater is heading upstream and vice versa.

This day marker is equivalent to a day marker buoy. If you encounter this daymark marine sign, always keep it on your left.

2 – Red Triangle Daymark


The triangle-shaped daymark is the counterpart of the green square-shaped daymark. This navigation control marker also bears a number (an even number).

As mentioned previously, the numbers fixed below the day markers indicate the direction of the boater. If the number increases, it means that the boater is heading upstream.

This red triangle day marker is also equivalent to a nun buoy. You must always keep this sign on your right when boating.

If you want to see what a day marker look like, you can take a special day markers boating trip. This will help you become familiar with the different sea markers.

Types of Navigational Markers

You might be wondering about the different types of day markers. As you learned, day markers are unlit and visible during daylight.

Therefore, if a navigational marker meets the criteria, it is safe to consider them day markers. I will enumerate and briefly describe the different types of navigational markers below:

1 – Lateral Markers


Lateral markers indicate which direction to follow or which side of the water is safe for navigation. They include buoys and other markers.

The typical types of lateral markers you will encounter are red cone-shaped Nun Buoy and a green cylindrical-shaped Can Buoy. The former should always be on your right side and the latter should always be on your left side.

In cases where a channel is split into two, you might see junction buoys that combine red and green colors. The same rules apply, if the green is on top, keep the ocean day marker on your left and if the red is on top, keep it on your right.

2 – Cardinal Markers

Cardinal marks indicate the direction of the safe navigable water. It is named after the cardinal parts of the compass.

3 – Safe Water Markers

As the name suggests, safe water markers indicate safe waters. This navigational marker is characterized by its vertical stripes. If you see this ocean marker, it means that it is safe to navigate the water around it.

4 – Isolated Danger Markers

This marker is erected or moored above the danger to alert boaters. If you see this hazard marker, it means that the water around it is safe for navigation.

5 – Special Markers

Special markers do not aid boaters in safe navigation. They are more like information markers that provide information that might interest the boater.

6 – Emergency Wreck Marking Buoy

These markers indicate newly discovered and un-surveyed areas. They signal mariners to be highly alert when navigating the surrounding water.

Non-lateral and Other Markers


Non-lateral markers indicate regulations and other information useful for boaters. Here are some non-lateral markers and other markers that may also qualify as day markers:

1 – Control Markers

Control markers tell the boaters about certain restrictions and regulations to follow. Their distinctive characteristic is an orange circle.

2 – Hazard Markers

These markers indicate that there is a danger ahead of you such as shoals and rocks. This is characterized by orange diamond symbols.

3 – Information Markers

This is a special marker that provides directions, distance, locations, and other relevant information to boaters. They feature an orange square symbol.

4 – Keep-Out Markers

These markers tell the mariner that the area is off limits. They carry an orange diamond symbol with a cross inside it.

5 – Mooring Buoy


A mooring buoy is a marker that floats in the water that weighs more than standard buoys. You can consider this as “a place to secure your boat marker”. This is where you can moor your boat in the middle of the ocean.

What is the Difference Between a Day Mark and Night Mark on a Lighthouse?


A lighthouse is a tower that aids sailors and boaters during their marine navigation. They vary in shape and size.

A lighthouse also features a day mark and a night mark. So, what is the difference between the two marks?

You’ve just learned about what is a day mark in the earlier sections. A day mark features distinctive marks that are highly visible during daylight. It doesn’t use light to convey a message to the mariner.

On the other hand, the night mark on a lighthouse is the one you see as your boat approaches the shore. The color and the pattern of the light that the lighthouse signals vary depending on what it communicates.

Frequently Asked Questions

Which side should you take if you see a green square day mark?

If you encounter a green square marker, keep the day marker on your left side. If the day marker is a red triangle, you should keep it on the right side.

Is the day beacon and day marker the same?

A day beacon is a sea mark that does not have a light. It holds the signboard that identifies its purpose. The signboard on a day beacon is called a day marker.

What is the usual shape and color of a day marker?

A day marker can either be red triangle shaped or green square shaped. The other possible colors of day markers are orange, yellow, and black.


You cannot imagine how a road without traffic signs can function. That is the same situation in marine coastal navigation. Navigational markers serve as the road sign in the sea. They ensure the safety buoyage of mariners and boaters.

During daytime trips, day markers are very useful. These markers ensure safety boating as they communicate helpful information. You might wonder if a day marker is visible at night. The answer is NO. Other markers assist the mariners during nighttime.

There you have it. The question “What is a day marker?” has been answered. 

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