5 Must-Have Features in a Marine Buoys

08 Sep.,2025

 

6 Basics of Marine Buoys: Things to Consider!

Marine buoys are of the utmost importance in maritime navigation. Their presence ensures ships’ safe passage. Despite their value, many people don’t understand the basics of marine buoys. This is because buoys have many types, which cause confusion.

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Some of them are used at a trim level to navigate small boats. On the flip side, some large buoys help maneuver the large vessels. Buoy selection depends on the needs. In this article, I’ll explain the purpose of buoys. You’ll also learn a few essential basics that can significantly impact buoy selection and use. So, let’s get started!

Overview of Marine Buoys

Marine buoys are floating devices installed in water bodies. They can be used at sea level and in river water. Their purpose is to show boats and vessels safe passage or channels in water. Remember, different buoys are available, and their purpose and work vary.

Have you heard of navigational or mooring buoys? Navigational ones help in navigating the ships in safe ways. The mooring buoys help keep the vessel in place. Just like that, there are many other types of buoys. Each of those buoys has its properties and characteristics.

Remember, buoys float at the water body’s surface, but they remain attached to the seabed or riverbed with an anchor and chain. The anchor’s weight does not move the buoys, keeping them in one place. Ships and boats can be anchored with these buoys and stay in one place.

You might get confused by a subtype of buoy known as boating buoys. These are also smaller-sized marine buoys. Their purpose is to navigate small boats in the water that may be unsafe for traveling. These boating buoys have many types, which we covered in the previous article.

6 Basics of Marine Buoys

Have you understood marine buoys? Let’s discuss some basic things related to them. This will help you better understand and choose the right buoys for your needs.

1- Materials of Buoys

Different materials are available for making buoys. However, the performance of each material varies. As you know, buoys remain in the water most of the time, demanding excellent durability and ruggedness to stay in good condition. Common materials include metals, plastics, and foam.

I don’t like metal as a buoy-making material. Why? It gets rusty when it remains in salty water for a long time. Plastics and foam offer exceptional performance and durability, making them stand out. Plastics can make buoys for many years if they remain safe from UV rays.

Manufacturers generally use High-density polyethylene (HDPE) plastics in buoys. It keeps the buoys lightweight yet very durable. However, foam is the ultimate solution for creating buoys. The question is: are foam-made buoys made of 100% foam? The answer is NO!

These buoys have an outer sheath of copper or metal. Inside, the cover and foam are filled. In simple terms, such buoys are known as Foam-filled Buoys. The significant advantage of foam-filled buoys is that their buoyancy is excellent. Even if the buoy is somewhat damaged, foam keeps it floating. Three main types of foams are used in such buoys.

Here is a table showing the difference between these foams:

Factor Polyurethane Foam Copolymer Foam Syntactic Foam Cost Low Medium High Depth Suitability Shallow (<1m) Up to 600 meters Deep (>600 meters) Water Absorption High (requires complete isolation). Moderate (closed-cell foam, some water resistance). Very low Durability Low Moderate (may deform under prolonged pressure). Very high Applications Surface buoys, shallow water markers. Mid-depth temporary applications. Deep-sea equipment, riser buoys, long-term use.

2- Buoyancy and Anchoring

Buoyancy indicates the floating nature of buoys. As I said earlier, all types of buoys are very lightweight and can easily stay on the surface of a water body. Even those buoys having outer covers made of metal also show decent buoyancy. If buoys don’t float, they are of no use. Remember, they help navigate by staying at the surface.

Have you ever seen a buoy staying in one place? They are lightweight and have buoyancy. Why do they not float and leave their position? That’s because of anchoring. Buoys consist of anchors, just like ships consist of anchors. Ships drop their anchor in water when they need to stay in one position.

The anchor is heavyweight and keeps the ship from drifting, right? The marine buoys are also attached to similar anchors. The buoy is connected to an anchor through chains. The anchor’s weight ensures buoys don’t drip away when the weather is terrible. If there is no anchor, tidal waves would displace those buoys.

3- Structure of Buoys

The shape of buoys can vary from one type to another. Remember, both shape and size have nothing to do with their basic structure. Buoys with tiny or more significant sizes will have the same basic structure. Let’s discuss the key components that make the structure of buoys.

  • Body: This is the primary component of the buoy that supports its buoyancy. Some buoys consist of foam in their cores. But that is not always the case, as some buoys don’t use foam in their core. The outer shield or covering then covers it. 
  • Hull or Outer Shell: The outer layer or cover protects the buoy’s body. This hull is generally made of robust, durable material. Such material can easily bear the shocks and are resistant to wear and tear. Generally, metal such as aluminum or plastic is used to make this outer shell.
  • Reinforcing mesh: Reinforced mesh is added between the core and outer shell. It has no connection with the foam present inside the core of the buoy. This reinforced mesh aims to increase the strength of the buoys. Some buoys also consist of pads that enhance shock absorption.
  • Ballast: Stability is a crucial parameter when it comes to buoys. If the buoy is unstable, it may not serve its purpose effectively. Ballast is the weightage point present at the bottom of buoys. It puts weight and keeps the buoy very stable at its point. Generally, metal is used to make this ballast.
  • Mooring System: Buoys consist of mooring systems to keep ships in one place. As I said earlier, an anchor keeps a buoy at one point. This buoy is connected with an anchor through chains. So, it remains stable. Ships can be attached with buoys as they do not move due to their anchoring system.

4- Signals & Sensors of Buoys

In the past, buoys had limited features. However, things have changed, and buoys are now equipped with modern technology. The signals and sensors on the buoys collect data on the water bodies. The sensors keep the operator tracking water movement, salinity, and temperature. 

Sensors and radar are also critical in the marine world. They help other ships and vessels know the location of these buoys. Remember, these buoys cannot be seen if the boats are far away. So, signals sent from the buoys help ships find these buoys. The radar of these buoys helps detect other ships in the sea.

Another critical parameter is marking and colors. Remember, buoys are marked with specific numbers and colored with different paints. These markings of the buoys convey meaningful information to boaters and other ship captains. You should read our article about the meaning of different buoys that we’ve already written.

5- Buoy Clamping System

A buoy clamping system helps in installing the buoy at any structure. It also helps when you attach an anchor to the buoy. Installing a buoy at any location requires a strong connection with the structure. In such cases, clamping systems come in handy. It consists of clamps, fasteners, or brackets. 

The clamp and fasteners ensure that the buoy doesn’t show instability. Remember, these claiming units are made with strong materials such as stainless steel. So, their chances of getting rusty are very minimal. Moreover, the workers take care of these clamps to ensure they remain in good shape for long. 

6- Buoy Level Gauge

A buoy level gauge is used to check the water level. As I said earlier, modern buoys collect data about water bodies, making them very useful and profitable. Understanding the water depth, change in depth, speed, and tidal movement is crucial. It helps monitor stations, keep the ships and vessels in safe water, and prevent accidents.

But the question is, how does this gauge system work? Gauges consist of sensors that move up and down according to the rise and fall of water. By tracking the movement of this sensor, operators easily check the water depth. They can also accurately determine the change in water depth over time.

Conclusion

There is no doubt that marine buoys are a great invention. In the past, their role and functionality were minimal. People used to use wood-made buoys to identify safe or unsafe water passages. However, innovation has taken over, and buoys have undergone significant changes with time.

Now, buoys with many sensors, radars, and markings are available in the market. Their usage has made marine traveling a lot easier. The boaters and ship captains easily understand the meaning of buoys and maneuver their ships accordingly. In this article, I’ve explained all the basics of buoys. 

Aids to Navigation - BoatUS Foundation

Aids to Navigation

Navigation Aid Basics

Unlike the roads and highways that we drive on, the waterways we go boating on do not have road signs that tell us our location, the route or distance to a destination, or of hazards along the way. Instead, the waterways have AIDS TO NAVIGATION (or ATONs), which are all of those man-made objects used by mariners to determine position or a safe course.

These aids also assist mariners in making a safe landfall, mark isolated dangers, enable pilots to follow channels, and provide a continuous chain of charted marks for precise piloting in coastal waters. The U.S. Aids to Navigation System is intended for use with nautical charts, which provide valuable information regarding water depths, hazards, and other features that you will not find in an atlas or road map.

For more information, please visit marine navigation equipment.

The term "aids to navigation" includes buoys, day beacons, lights, lightships, radio beacons, fog signals, marks and other devices used to provide "street" signs on the water. Aids To Navigation include all the visible, audible and electronic symbols that are established by government and private authorities for piloting purposes.

The Coast Guard is the agency responsible for maintaining aids to navigation on U.S. waters that are under federal jurisdiction or that serve the needs of the U.S. armed forces. On bodies of water wholly within the boundaries of a single state, and not navigable to the sea, the Coast Guard grants the state responsibility for establishing and maintaining aids to navigation. The U.S. Corps of Engineers is responsible for many of the canals, dams, locks, and other man-made waterways in the country. The Corps also is responsible for the regulation of mooring buoys in all navigable U.S. Waters.

The individual Coast Guard districts also may grant permission to private groups and citizens to place "Private" Aids to Navigation. These aids allow individuals or organizations the ability to mark privately maintained channels, zones or waterways. These aids must be pre-approved, and must be maintained by the individual or organization.

Types of Aids to Navigation

The term "aids to navigation" encompasses a wide range of floating and fixed objects (fixed meaning attached to the bottom or shore), and consist primarily of:

  • Buoys - floating objects that are anchored to the bottom. Their distinctive shapes and colors indicate their purpose and how to navigate around them.
  • Beacons - structures that are permanently fixed to the sea-bed or land. They range from structures such as light houses, to single-pile poles. Most beacons have lateral or non-lateral aids attached to them. Lighted beacons are called "LIGHTS", unlighted beacons are "DAYBEACONS".

Both Buoys and Beacons may have lights attached, and may have a sound making device such as a gong, bell or horn. Both Buoys and Beacons may be called "marks".

Aids to Navigation Systems

Depending on where you boat in America, you may see several differences in how navigational marks are colored, numbered, or lighted. Regardless of the location, buoys and beacons are placed in very specific locations, to mark either a particular side of a waterway, or some other navigational feature. The primary system in use is referred to the "U.S. Aids to Navigation System". The U. S. Coast Guard maintains this system in conformance to the International Association of Lighthouse Authorities (IALA), which is an international committee which seeks to ensure safe navigation, primarily through the use of common navigation aids and signals.

The "LATERAL" system is the familiar RED RIGHT RETURNING system, meaning that on all navigable waters returning from sea, the red even-numbered marks are on the starboard (right) side of the channel and the green odd-numbered marks are on the port (left) side of the channel. Numbers on the marks ascend when traveling from sea to harbor--if you don't have a compass and become disoriented on the water, you will always know you are heading upstream if the buoy numbers get larger as you travel.

Port Side Odd Numbered Aids

Port side numbered aids are green in color, odd numbered and may be lighted. Port side marks are located on the left side of the waterway as you travel upstream, and the buoy numbers will increase as you head upstream. (Chart depictions are shown next to the marks) Port-Side Buoys have a cylindrical above-water appearance, like a can or drum floating on its axis. Commonly referred to as "CAN" buoys. Beacons - Port side beacons have square marks attached to them, with two shades of color and a reflective border.

Starboard Side Even Numbered Aids

Starboard aids are red in color, evenly numbered and will be on your right side as you travel upstream. Buoy numbers increase as you head upstream, and may have a red light. Starboard-side buoys have an above-water appearance like that of a cylinder topped with a cone, pointed end up. The cone may come to a point or be slightly rounded. Commonly referred to as "NUN" buoys. Starboard-side Beacons have triangular marks attached to them, with two shades of color and a reflective border.

Intracoastal Waterway

For the sea buoys that delineate channels off the coast of the United States, and for the Intracoastal Waterway (ICW), red is on the right (shore side) when proceeding clockwise around the U. S. from the East Coast to the Gulf Coast, or proceeding north along the West Coast.

ICW marks are further identified by a small yellow reflector at the bottom of the mark. The same port and starboard marks shown above will look like the following.

Numbers on the marks ascend when traveling in this direction. Where the IALA-B and ICW marks meet, one must be very careful to observe the change in meaning by referral to local charts.

Other Aids - Marks

Dayboards

These diamond shaped marks are used to help the vessel operator determine location on a nautical map. When you see a dayboard, and find the corresponding mark on the chart, you know your precise location. They may be lettered, and may be lighted with a white light. Their color reflects that of nearby lateral marks.

Safe Water Marks

These marks are used to mark fairways, mid-channels, and offshore approach points. They have unobstructed water on all sides. These marks may be lettered, and may be lighted with a white light. They may also have a red top mark.

Isolated Danger Marks

These indicate a danger which may be passed on all sides. They are erected on, or moored on or near danger. They should not be approached closely without special caution. They may be lighted, and they may be lettered.

Special Marks

Special marks have no lateral significance (meaning they don't tell you which side of the channel or river you may be on). These marks are used to mark a special feature or area. These include area limits for anchorages, fishing grounds, or dredging/spoil areas. These buoys may be lighted, and if they are it will be a fixed or flashing yellow light. Shape is optional, but usually follows the shape of the navigation buoys that it is positioned near.

Other Aids - Miscellaneous

Mooring Bouys

Mooring buoys come in two different shapes; spherical and cylindrical. Both have white bodies with a solid blue horizontal band on the center of the buoy. Mooring buoys may have a white reflector, or a white light attached to them. Mooring buoys are the ONLY buoys to which you may legally tie your boat. Buoys are generally placed in marked anchorage areas, and you must take caution if you are traveling near buoy areas. Check your state boating guide for particular operating restrictions in anchorage areas.

Ranges

These are pairs of unlighted or lighted fixed aids that when observed in line show the pilot to be on the centerline of a channel.

Regulatory Marks

Regulatory Marks re designed to assist boaters by informing them of special restrictions or dangers that they are approaching. Regulatory marks are white "can" buoys that have an orange shape on them. The mark will give either a warning or instructions on how to proceed. The shape determines what type of mark it is.

  • An open diamond shape signifies danger.
  • A diamond with a cross in it signifies an exclusion area that you may not enter.
  • A circle indicates an upcoming operating restriction, such as a speed limit.
  • A square or rectangular shape is used for conveying instructions.

Uniform State Waterway Marking System

This system was originally intended for use by states on lakes and inland waterways that weren’t covered by nautical charts. The buoys used in the Uniform State Waterway Marking System (USWMS) used colors, shapes and marking patterns that differed greatly from the U.S. Aids to Navigation System (ATONS).

In , the U.S. Coast Guard decided to phase out the USWMS to avoid potential confusion of boaters and instead, favored using the more widely recognized ATONS. By , the USWMS was completely phased out. Below are a few of the differences from the federal system you should know about.

Here's a summary of the important changes regarding the phase out of USWMS:

  • The old USWMS black port side channel markers are now GREEN can buoys.
  • The old USWMS red starboard side channel markers are now red NUN buoys.
  • The old USWMS red and white vertically striped buoys have been replaced by one of the following: a red or green channel marker directing safe passage, an orange and white regulatory marker, or a red and black isolated danger marker.
  • The old USWMS white buoys topped with black or red bands, have been replaced by one of the following: a red or green channel marker directing safe passage, an orange and white regulatory marker, or a red and black isolated danger marker.

Lateral Aids

The state system differs in several ways, in case you happen to encounter them. These aids also assist mariners in making a safe landfall, mark isolated dangers, enable pilots to follow channels, and provide a continuous chain of charted marks for precise piloting in coastal waters. The U.S. Aids to Navigation System is intended for use with nautical charts, which provide valuable information regarding water depths, hazards, and other features that you will not find in an atlas or road map.

  • Buoys are placed in pairs, and you pass between them.
  • State buoys do use the color red for starboard side marks, but they are cans, and not nuns, while port buoys are black and can-shaped.
  • Numbers on buoys go up as you head upstream, or towards the head of navigation.
  • Portside buoys use the color black instead of green.
  • Portside buoys are numbered with odd numbers.
  • Portside buoys may show a green reflector or light.
  • Starboard side buoys are red.
  • Starboard side buoys are numbered with even numbers.
  • Starboard side buoys may show a red reflector or light.

Other State Aids

Red-topped White Buoys

  • Signify that you may pass south or west of buoy
  • May be numbered
  • May show a white reflector or light

Black-striped white Buoys - Inland Waters Obstruction Mark

  • Signify that you should not pass between mark and nearest shore
  • May be lettered
  • May show white reflector or light
  • Replaces the old red and white vertically striped buoy

Black-topped White Buoys