A buoy (/bɔɪ/, North America more commonly, but not exclusively /ˈbuːi/)[1] is a floating device that can have many purposes. It can be anchored (stationary) or allowed to drift with ocean currents. The etymology of the word is disputed.[2]

Buoy seal
A sea lion on navigational buoy #14 in San Diego Harbor.
Green can #11 near the mouth of the Saugatuck River.


Navigational aids

  • Buoy racing is the most prevalent form of yacht racing
  • Emergency wreck buoy – An Emergency Wreck Buoys provides a clear and unambiguous means of marking new wrecks. This buoy is used as a temporary response, typically for the first 24–72 hours. This buoy is coloured in an equal number of blue and yellow vertical stripes and is fitted with an alternating blue and yellow flashing light. This has come about due to the collisions which occurred in the Dover Straits in 2002 when vessels struck the new wreck of the MV Tricolor.[3]
  • Ice marking buoys – used for marking ice holes in frozen lakes and rivers, so that snowmobiles do not drive over the holes.
  • Large Navigational Buoy (LNB or Lanby buoy) is an automatic buoy over 10m high equipped with a powerful light monitored electronically as a replacement for lightships.[4] A LNB may be marked on charts as a "Superbuoy."[5]
  • Lobster trap buoys – brightly colored buoys used for the marking of lobster trap locations so the person lobster fishing can find their lobster traps. Each lobster fisherman has his or her own color markings or registration numbers so they know which ones are theirs. They are only allowed to haul their own traps and must display their buoy color or license number on their boat so law enforcement officials know what they should be hauling. The buoys are brightly colored with highly visible numbers so they can be seen under conditions when there is poor visibility like rain, fog, sea smoke, etc.[6][7]
  • lateral marker buoy
  • Safe water mark or Fairway Buoy – a navigational buoy which marks the entrance to a channel or a nearby landfall
  • Sea mark – aids pilotage by marking a maritime channel, hazard and administrative area to allow boats and ships to navigate safely. Some navigational buoys are fitted with a bell or gong, which sounds when waves move the buoy
  • Wreck buoy – a buoy to mark a wrecked ship to warn other ships to keep away because of unseen hazards.


  • Lifebuoy – used as a life saving buoy designed to be thrown to a person in the water to provide buoyancy. Usually has a connecting line allowing the casualty to be pulled to the rescuer
  • Self-locating datum marker buoy (SLDMB) – A 70% scale Coastal Ocean Dynamics Experiment (CODE)/Davis-style oceanographic surface drifter with drogue vanes between 30 and 100 cm deep.[8] This particular surface drifter is designed specifically for deployment from a U.S. Coast Guard vessel or airframe for search and rescue. Since the SLDMB has a very small surface area above the ocean surface and a high underwater surface area, there is very little leeway in response to the direct forcing of winds and waves.[9]
  • Submarine rescue buoy – used for release in case of emergencies or for communication



  • Profiling buoy – specialized models which adjust buoyancy so that they will sink at a controlled rate to 2,000 metres below the surface while measuring sea temperatures and salinity. After a time, typically 10 days, the buoy returns to the surface, transmits its data via satellite, and then sinks again.[11] See Argo (oceanography).
  • Tsunami buoys – anchored buoys that can detect sudden changes in undersea water pressure are used as part of tsunami warning systems in the Pacific Tsunami Warning Center and Indian Oceans.
  • Wave buoy – used to measure the movement of the water surface as a wave train. The wave train is analysed to determine statistics like the significant wave height and period, and wave direction.
  • Weather buoys – equipped to measure weather parameters such as air temperature, barometric pressure, wind speed and direction and to report these data via satellite radio links such as the purpose-built Argos System or commercial satellite phone networks to meteorological centres for use in forecasting and climate study. May be anchored (moored buoys) or allowed to drift (drifting buoys) in the open ocean currents. Position is calculated by the satellite. Weather buoys are sometimes referred to as ODAS buoys or Ocean Data Acquisition Systems[12] and may be marked on charts as "Superbuoys."[5]


  • Mooring buoys – used to keep one end of a mooring cable or chain on the water's surface so that ships or boats can tie on to it. Many marinas mark these with a number and assign it to a particular vessel, or rent it out to transient vessels.
  • Tripping buoys – used to keep one end of a 'tripping line' on the water's surface so that a stuck anchor can more easily be freed


  • Marker buoys – used in naval warfare, particularly anti-submarine warfare, is a light-emitting or smoke-emitting, or both, marker using some kind of pyrotechnic to provide the flare and smoke. It is commonly a 3-inch (76 mm) diameter device about 20 inches (500 mm) long that is set off by contact with seawater and floats on the surface. Some markers extinguish after a set period and others are made to sink.
  • Sonobuoy – used by anti-submarine warfare aircraft to detect submarines by SONAR
  • Target buoy – used to simulate target (like small boat) in live fire exercise by naval and coastal forces, usually targeted by weapons (medium size) like HMG's, rapid fire cannons (20 or so mm), autocannons (bigger ones up to 40 and 57mm) and also anti-tank rockets.

Specific forms

  • DAN buoy – has several meanings:
    • A large maritime navigational aid providing a platform for light and radio beacons
    • A lifebuoy with flags used on yachts and smaller pleasure craft
    • A temporary marker buoy used during Danish seine fishing to mark the anchor position of a net.
    • A temporary marker buoy set by danlayers during minesweeping operations to indicate the boundaries of swept paths, swept areas, known hazards, and other locations or reference points.
    • A temporary marker buoy set to mark a man overboard position.
  • Spar buoy – a tall, thin buoy that floats upright in the water, e.g. R/P FLIP.


  • The space buoy is a common element in science fiction that refers to a stationary object in outer space that provides navigation data or warnings about that particular area.
  • Mail buoy – an imaginary buoy used as a prank in the US Navy[13]

Other uses

  • The word "buoyed" can also be used figuratively. For example, a person can buoy up ('lift up') someone's spirits by providing help and empathy.[14]
  • Buoys are used in some wave power systems to generate electrical power.[15]
  • George A. Stephen, founder of Weber-Stephen Products Co., invented the kettle grill by cutting a metal buoy in half and fashioning a dome shaped grill with a rounded lid.[16]



Several different buoys at a storage depot.


A buoy used as turn marker for sailing races.

Iron Buoys Great Barrier Island

Old iron buoys, most likely for mooring.


Children playing on a buoy in the Volga

Boa spiaggiata

A buoy beached at Sebastian Inlet State Park.

Telephone buoy of HMS Nordkaparen (Nor)

Emergency buoy of the Swedish submarine Nordkaparen

Gas buoy stranded on land by hurricane

Gas buoy stranded on land after 1915 Galveston Hurricane, near Texas City, Texas

Boya Buoy

Starboard lateral Buoy (Lateral Mark - System B - IALA ) as Channel Marker Buoy at "Río de la Plata" river, Buenos Aires, Argentina

Envirtech Tsunami Buoy MKIII

Envirtech Tsunami Buoy MKIII before deployment in Andaman Sea

Lobster buoys

Lobster buoys hanging on a tree, Sprucehead Island, Maine, United States


Buoys in dry storage, Homer, Alaska


Drifting Buoy fitted with a Barometer (DBi)

Ship1258 - Flickr - NOAA Photo Library

Buoy undergoing repair

Ring buoy with light

Ring life buoy with a light on a cruise ship

See also


  1. ^ buoy in the American Heritage Dictionary
  2. ^ buoy in tne Online Etymology Dictionary
  3. ^ "Archived copy". Archived from the original on 2014-07-02. Retrieved 2014-05-26.CS1 maint: Archived copy as title (link)
  4. ^ "Large Navigational Buoys (LNB)". United States Coast Guard. Retrieved Jul 6, 2015.
  5. ^ a b National Oceanic and Atmospheric Administration (2013). US Chart No. 1. Silver Spring: NOAA. p. 89.
  6. ^ Cobb, John N., "The Lobster Fishery of Maine", Bulletin of the United States Fish Commission, Vol. 19, Pages 241–265, 1899; from Project Gutenberg
  7. ^ Taft, Hank; Taft, Jan, A Cruising Guide to the Maine Coast and the Maine Coast Guides for Small Boats, Peaks Island, Maine : Diamond Pass Publishing, 5th Edition, 2009. Cf. Chapter: "BUOY, OH BUOY" Archived 2008-11-18 at the Wayback Machine, and Chapter: "Fisherman, Lobsterboats, and Working Harbors" Archived 2012-03-20 at the Wayback Machine
  8. ^ [METOCEAN. (2008). METOCEAN SLDMB: Operating & Maintenance Manual (Version 3.0 ed.) Retrieved from http://www.metocean.com.
  9. ^ [Bang, I., Mooers, C. N. K., Haus, B., Turner, C., Lewandowski, M. (2007). Technical Report: Surface Drifter Advection and Dispersion in the Florida Current Between Key West and Jacksonville, Florida. Technical Report.].
  10. ^ Davies, D (1998). "Diver location devices". Journal of the South Pacific Underwater Medicine Society. 28 (3). Retrieved 2013-04-16.
  11. ^ Kery, SM (1989). "Diving in support of buoy engineering: The RTEAM project". In: Lang, MA; Jaap, WC (ed). Diving for Science…1989. Proceedings of the American Academy of Underwater Sciences annual scientific diving symposium 28 September – 1 October 1989 Wood Hole Oceanographic Institution, Woods Hole, Massachusetts, USA. Retrieved 2013-04-16.
  12. ^ IALA (2008). "International Dictionary of Marine Aids to Navigation – ODAS buoy". Retrieved 10 December 2016.
  13. ^ "Pranks: Some old, some new". USS RICH. USS RICH Association.
  14. ^ "buoy". Oxford English Dictionary. Vol II (2nd ed.). Oxford University Press. 1989. p. 661. verb, sense 3.
  15. ^ Buoy System Harnesses Wave Energy - ABC News
  16. ^ George Stephen, Company Founder and Inventor of the Weber Kettle Grill Archived June 23, 2007, at the Wayback Machine

External links

Albano buoy system

The Albano lane system is a method of marking kayak, canoe and rowing race courses using lines of buoys. It was first used internationally in the 1960 Summer Olympics held on Lake Albano, Italy. It has since become an international standard for most FISA events and is used in Olympic rowing events.

Buoy anti-tank obstacle

Buoy is a British type of anti-tank obstacle used to block roads intended to impede enemy movement. Buoys were widely deployed during the invasion crisis of 1940–1941. Each buoy was a truncated cone of concrete with a rounded bottom, about 2 feet 9 inches (84 cm) high, and with a 2 inches (50 mm) diameter hole through the axis. They would be placed in at least five rows across a roadway.

Buoys were intended as an alternative to a simple cylinder of concrete. The advantage of buoy was that it could be used to block or unblock a road quickly. Passing a rod or crossbar through a pair of buoys formed a wheeled axle that could easily be rolled into place; when the axle was removed the buoys could be separated and stood up. Although easily knocked over, the conical shapes could not be rolled very far, they would move unpredictably and out of the field of view of a tank driver, making it difficult to avoid them. They were eventually judged to be ineffective and phased out.Extant examples are often found by the roadside today.

Buoy tender

A buoy tender is a type of vessel used to maintain and replace navigational buoys. The name is also used for someone who works on such a vessel and maintains buoys.

The United States Coast Guard uses buoy tenders to accomplish one of its primary missions of maintaining all U. S. Aids to Navigation (ATON).

The Canadian Coast Guard uses multi-use vessels (icebreaker and navigation aid) with the buoy tender platform.

Deep-ocean Assessment and Reporting of Tsunamis

Deep-ocean Assessment and Reporting of Tsunamis (DART) is a component of an enhanced tsunami warning system.

By logging changes in seafloor temperature and pressure, and transmitting the data via a surface buoy to a ground station by satellite, DART enables instant, accurate tsunami forecasts. In Standard Mode, the system logs the data at 15-minute intervals, and in Event Mode, every 15 seconds. A 2-way communication system allows the ground station to switch DART into Event Mode whenever detailed reports are needed.

Diving shot

A diving shot, or more formally, diving shot line is an item of diving equipment consisting of a weight (the shot), a line and a buoy. The weight is dropped on the dive site. The line connects the weight and the buoy and is used by divers to as a visual and tactile reference to move between the surface and the dive site more safely and more easily, and as a controlled position for in-water staged decompression stops

A "lazy shot" is a shot which is suspended above the bottom. It may be tethered to the main shot line at a convenient depth. It is used for decompression and frees the main shot line for other divers. The lazy shot's line does not need to be longer than the decompression depth and is often only deep enough for the longer stops. It only needs a weight heavy enough to provide diver buoyancy control and sufficient buoyancy to avoid being dragged down under reasonably foreseeable circumstances.


A lifebuoy, ring buoy, lifering, lifesaver, life donut, life preserver or lifebelt, also known as a "kisby ring" or "perry buoy", is a life saving buoy designed to be thrown to a person in the water, to provide buoyancy and prevent drowning. Some modern lifebuoys are fitted with one or more seawater-activated lights, to aid rescue at night.

The lifebuoy is usually ring- or horseshoe-shaped and has a connecting line allowing the casualty to be pulled to the rescuer in a boat. They are carried by ships and are also located beside bodies of water that have the depth or potential to drown someone. They are often subjected to vandalism which, since the unavailability of lifebuoys could lead to death, may be punished by fines (up to £5,000 in the United Kingdom) or imprisonment.

The "kisby ring", or sometimes "Kisbie ring", is thought to be named after Thomas Kisbee (1792–1877) who was a British naval officer.The UK Royal Life Saving Society considers lifebuoys unsuitable for use in swimming pools because throwing one into a busy pool could injure the casualty or other pool users. In these locations, lifebuoys have been superseded by devices such as the torpedo buoy.In the United States, Coast Guard approved lifebuoys are considered Type IV personal flotation devices. At least one Type IV PFD is required on all vessels 26 feet or more in length.

List of United States Coast Guard cutters

The List of United States Coast Guard Cutters is a listing of all cutters to have been commissioned by the United States Coast Guard during the history of that service. It is sorted by length down to 65', the minimum length of a USCG cutter.

Lobster buoy hitch

The lobster buoy hitch is similar to the buntline hitch, but made with a cow hitch around the standing part rather than a clove hitch.

Like the buntline hitch, this knot is strong, secure and compact.

Practical joke

A practical joke, or prank, is a mischievous trick played on someone, generally causing the victim to experience embarrassment, perplexity, confusion, or discomfort. A person who performs a practical joke is called a "practical joker". Other terms for practical jokes include gag, jape, or shenanigan.

Practical jokes differ from confidence tricks or hoaxes in that the victim finds out, or is let in on the joke, rather than being talked into handing over money or other valuables. Practical jokes are generally lighthearted and without lasting impact; they aim to make the victim feel humbled or foolish, but not victimized or humiliated. Thus most practical jokes are affectionate gestures of humour and designed to encourage laughter. However, practical jokes performed with cruelty can constitute bullying, whose intent is to harass or exclude rather than reinforce social bonds through ritual humbling.Some countries in Western culture traditionally emphasize the carrying out of practical jokes on April Fools' Day.


A sonobuoy (a portmanteau of sonar and buoy) is a relatively small buoy (typically 13 cm or 5 in, in diameter and 91 cm or 3 ft long) expendable sonar system that is dropped/ejected from aircraft or ships conducting anti-submarine warfare or underwater acoustic research.

Surface marker buoy

A surface marker buoy, SMB or simply a blob is a buoy used by scuba divers, with a line, to indicate the diver's position to their surface safety boat while the diver is underwater. Two kinds are used; one (SMB) is towed for the whole dive, and indicates the position of the dive group, and the other (DSMB) is deployed towards the end of the dive as a signal to the surface that the divers have started to ascend. Both types can also function as a depth reference for controlling speed of ascent and accurately maintaining depth at decompression stops.

A "safety sausage" is a low volume tubular buoy inflated at or near the surface to increase visibility of the diver.

Thames Estuary

The Thames Estuary is where the River Thames meets the waters of the North Sea, in the south-east of Great Britain.

The limits of the estuary have been defined in several ways:

Although physically the head of Sea Reach or the Kent / Essex Strait, south of Canvey Island on the northern (Essex) shore presents a western boundary, the Tideway itself can be considered estuarine; it starts in south-west London at Teddington/Ham.

The Yantlet Line between the Crowstone in Chalkwell and the London Stone on the Isle of Grain.

The Nore sandbank between Havengore Creek, Essex, and Warden Point, Kent.

The eastern boundary of the estuary suggested in a Hydrological Survey of 1882-9 is a line drawn from North Foreland, Margate, Kent via the Kentish Knock lighthouse to Harwich in Essex. It is to this line that the typical estuarine sandbanks extend. The estuary downstream of the Tideway has a tidal movement of 4 metres, moving at a speed of up to 2.6 knots (4.8 km/h; 3.0 mph).

A line from Warden Point on the Isle of Sheppey Kent via Sea Reach No. 1 buoys to Havengore Head Essex.The estuary is one of the largest of 170 such inlets on the coast of Great Britain. It constitutes a major shipping route: its thousands of movements each year include large oil tankers, container ships, bulk carriers and roll-on/roll-off (ro-ro) ferries entering the estuary for the Port of London and the Medway Ports of Sheerness, Chatham and Thamesport.

The traditional Thames sailing barge worked in this area, designed to be suitable for the shallow waters in the smaller ports. More recently one of the largest wind farms in the UK has been developed in the estuary, located 8.5 km north of Herne Bay, Kent. The farm contains 30 wind turbines generating a total of 82.4MW of electricity. The much larger 630 MW London Array was inaugurated in 2013.

This area has had several proposed sites for the building of a new airport to supplement, or even to replace Heathrow/Gatwick. In the 1960s Maplin Sands was a contender; in 2002 it was to be at Cliffe, Kent. The new airport would be built on a man-made island in the estuary north of Minster-in-Sheppey

There is also some discussion about the need for a Lower Thames Crossing in order to alleviate traffic congestion at Dartford.

The Thames Estuary is the focal part of the 21st-century toponym, the "Thames Gateway", designated as one of the principal development areas in Southern England.

The Bell Buoy

"The Bell Buoy" is a poem by Rudyard Kipling. It was first published with illustrations in Saturday Review, Christmas Supplement 1896 and then published in McClure's Magazine in February 1897 as "The Bell-Buoy", with illustrations by Oliver Herford. It was also included in the 1903 collection The Five Nations.

Some changes to the wording occurred sometime between the edition in McClure's and when it was collected in Rudyard Kipling's verse: inclusive edition, 1885-1918 (1919) as "The Bell Buoy". The other changes are minor and some may be the correction of printing errors.

T. S. Eliot included the poem in his 1941 collection A Choice of Kipling's Verse.

Type 744 buoy tender

Type 744 buoy tender and its derivatives with the NATO reporting name Yannan (延南) class is a class of Chinese buoy tender that is in service with the People's Liberation Army Navy (PLAN) and Chinese civilian governmental establishments. It is a boat or vessel which services and replaces buoys.

Type 999 buoy tender

Type 999 buoy tender is a series of Chinese buoy tenders that was first entered service with Chinese navy in 1965. Type 999 buoy tender adopts an U shaped hull, and to maintain positions in bad weather during operations, it is equipped with retractable stabilizing fins that are extended at work, and retracted in transit. Type 999 is capable of lifting 2-ton weight and has self right capability when rolling up to 45 degrees. After the first unit was completed at the end of 1964, preliminary trials were conducted under sea state 8 in the January of the following year, which proved successful. Further tests were conducted in Zhoushan in May 1965, and the after passing the test, it entered the service in the same year. Subsequently, a total of 12 were completed. These units are followed by an upgraded version designated as Type 999G, with displacement increased by 3 tons to 98, and a total of three were built. The final upgraded version of Type 999 buoy tender is Type 999HG, which improved living conditions onboard by upgrading subsystems such as cooking equipment. Specification:

Displacement (t): 95

Length (m): 28

Width (m): 5.2

Speed (kt): 11.5

Endurance (nm): 500

Propulsion (hp): 300

Armament: twin 14.5 mm machine gun

USCGC Sundew (WLB-404)

USCGC Sundew (WLB-404) is a 180-foot (55 m) sea going buoy tender (WLB). A Iris, or C-class tender, it was built by Marine Iron and Shipbuilding Corporation in Duluth, Minnesota. Sundew's preliminary design was completed by the United States Lighthouse Service and the final design was produced by Marine Iron and Shipbuilding Corporation in Duluth for the U.S. Coast Guard. On 29 November 1943 the keel was laid. It was launched on 8 February 1944 and commissioned on 24 August 1944. The original cost for the hull and machinery was $861,589.

Sundew is one of 39 original 180-foot (55 m) seagoing buoy tenders built between 1942-1944. All but one of the original tenders, USCGC Ironwood, were built in Duluth. Like all of these tenders, Sundew was named after a plant, in this case the sundew, a carnivorous plant from the genus Drosera.

In 1958, Sundew was assigned to Charlevoix, Michigan, and the following November helped in the rescue of two survivors from the Carl D. Bradley when it sank in a storm on Lake Michigan 47 miles (76 km) west-northwest of Charlevoix. Sundew remained at Charlevoix until 1981, when she was replaced by USCGC Mesquite. Sundew was then moved to Duluth, Minnesota, where it served until it was retired in 2004.

Sundew served 60 years for the Coast Guard and was decommissioned and retired on May 27, 2004. As part of the decommissioning, the vessel was given to the city of Duluth, its last home port, to be used as a museum ship. The services provided by the Sundew were taken up by USCGC Alder.

Due to a drop in tourism revenue, in 2009 the city of Duluth sold Sundew to local residents, Jeff & Toni Foster and David Johnson & Mary Phillipp. Sundew moved from its museum location in Duluth in the spring of 2010, and currently (2017) occupies a private slip near Duluth's Great Lakes Aquarium.

USCG seagoing buoy tender

The USCG seagoing buoy tender is a type of United States Coast Guard cutter originally designed to service aids to navigation throughout the waters of the United States, and wherever American shipping interests require. The U.S. Coast Guard has maintained a fleet of seagoing buoy tenders dating back to its origins in the U.S. Light House Service (USLHS). These ships originally were designated with the hull classification symbol WAGL, but in 1965 the designation was changed to WLB, which is still used today.

Two classes of the WLB cutters have been produced. The older class, the 180 ft-class cutters, were 180 feet (55 m) long. Thirty-nine of these vessels were built from 1942–1944. All but one were constructed in the shipyards of Duluth, Minnesota. The 180 fleet, many of which served for more than 50 years, all went through different mid-life modifications that essentially resulted in three different classes of ship. All of the 180s are now retired and have been replaced with the new 225-foot (69 m) Juniper-class cutters. The last 180-foot cutter, USCGC Acacia, was decommissioned on 7 June 2006.

The Jonquil class of 189-foot (58 m) buoy tenders were U.S Army built mine planters acquired by the Coast Guard after World War II. Built around 1942, these vessels were designed for diesel engines but low pressure steam plants were installed instead.

The new Juniper buoy tenders are designed and operated as multi-mission platforms. While the 180s also performed other Coast Guard missions, they lacked the speed, communications, navigation and maneuverability of the new Junipers. Today, the Junipers conduct almost as much law enforcement as aid to navigation work; they are also outfitted to handle oil spill recovery, search and rescue, homeland security, and some ice breaking operations.

United States Coast Guard Buoy Depot, South Weymouth

United States Coast Guard Buoy Depot, South Weymouth is a United States Coast Guard facility located in Weymouth, Massachusetts. It is located to the southeast of the South Weymouth MBTA station and west of the former Naval Air Station South Weymouth.

Weather buoy

Weather buoys are instruments which collect weather and ocean data within the world's oceans, as well as aid during emergency response to chemical spills, legal proceedings, and engineering design. Moored buoys have been in use since 1951, while drifting buoys have been used since 1979. Moored buoys are connected with the ocean bottom using either chains, nylon, or buoyant polypropylene. With the decline of the weather ship, they have taken a more primary role in measuring conditions over the open seas since the 1970s. During the 1980s and 1990s, a network of buoys in the central and eastern tropical Pacific Ocean helped study the El Niño-Southern Oscillation. Moored weather buoys range from 1.5–12 metres (5–40 ft) in diameter, while drifting buoys are smaller, with diameters of 30–40 centimetres (12–16 in). Drifting buoys are the dominant form of weather buoy in sheer number, with 1250 located worldwide. Wind data from buoys has smaller error than that from ships. There are differences in the values of sea surface temperature measurements between the two platforms as well, relating to the depth of the measurement and whether or not the water is heated by the ship which measures the quantity.

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