A sea mark, also seamark and navigation mark, is a form of aid to navigation and pilotage that identifies the approximate position of a maritime channel, hazard, or administrative area to allow

boat A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size or capacity, its shape, or its ability to carry boats. Small boats are typically used on inland waterways s ...

ship A ship is a large watercraft, vessel that travels the world's oceans and other Waterway, navigable waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research and fishing. Ships are generally disti ...

s, and seaplanes to navigate safely. There are three types of sea mark: beacons fixed to the seabed or on shore, towers (sometimes rock

cairn A cairn is a human-made pile (or stack) of stones raised for a purpose, usually as a marker or as a burial mound. The word ''cairn'' comes from the (plural ). Cairns have been and are used for a broad variety of purposes. In prehistory, t ...

s) built on the shore or on a submerged rock/object (especially in calmer waters), and buoys (consisting of a floating object that is usually anchored to a specific location on the bottom of the sea or to a submerged object). Sea marks are used to indicate channels, dangerous rocks or shoals, mooring positions, areas of speed limits, traffic separation schemes, submerged

shipwreck A shipwreck is the wreckage of a ship that is located either beached on land or sunken to the bottom of a body of water. It results from the event of ''shipwrecking'', which may be intentional or unintentional. There were approximately thre ...

s, and for a variety of other navigational purposes. Some are only intended to be visible in daylight ('' daymarks''), others have some combination of lights, reflectors, fog bells, foghorns, whistles and radar reflectors to make them usable at night and in conditions of reduced visibility. Marks are shown on nautical charts, using symbols that indicate their colour, shape and light characteristic, and are usually identified by name or number. In a wider sense the phrase "sea mark" is often understood to include all types of landmarks, structures and devices that can be used to provide warning and guiding signs to mariners. Thus a sea mark can be and often is located on dry land. Examples of land-based sea marks are various signal lights and leading marks. The latter are mainly used to indicate the centerline of a fairway in narrow passages. Sea marks may also on occasion be used to help mark the boundaries of defensive sea minefields, or the safe lanes through same, especially during wartime.

Definitions

The International Association of Lighthouse Authorities defines one system of marks specifying the

shape A shape is a graphics, graphical representation of an object's form or its external boundary, outline, or external Surface (mathematics), surface. It is distinct from other object properties, such as color, Surface texture, texture, or material ...

s, colours and characteristic lights of buoys depending on their purpose, the IALA Maritime Buoyage System. For historical reasons, there are two regions of lateral marks in use: * IALA ''Region B'' in the

Americas The Americas, sometimes collectively called America, are a landmass comprising the totality of North America and South America.''Webster's New World College Dictionary'', 2010 by Wiley Publishing, Inc., Cleveland, Ohio. When viewed as a sing ...

, the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and t ...

and

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

* IALA ''Region A'' everywhere else. The two regions differ principally in the colours used to denote the two sides of a channel. When approaching a harbour from seaward, ''Region A'' places conical green marks to starboard and cylindrical red ones to

port A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Hamburg, Manch ...

. In ''Region B'' these are replaced with conical red marks to starboard and cylindrical green ones to port. This can be remembered (for ''Region B'') with the

mnemonic A mnemonic device ( ), memory trick or memory device is any learning technique that aids information retention or retrieval in the human memory, often by associating the information with something that is easier to remember. It makes use of e ...

''"Red, right, return"''. Another ''Region B'' mnemonic, which also helps with buoy numbering is "Even Red Left Port" (as in Eric the Red) - Even Numbered buoys are red, on your left (port) side leaving port. In any case, since in many harbours it is not always apparent which direction is seaward, buoys should be used in connection with the appropriate nautical chart. Additionally, since marks may be off station due to collision with ships, storms or other factors, they should be used with caution and not relied on solely for

navigation Navigation is a field of study that focuses on the process of monitoring and controlling the motion, movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navig ...

. The two regions are often referred to as two systems, which was the original intent. In 1980 it was decided however to combine these systems and distinguish between regions.

Image gallery

File:Buoy seal.jpg, Red buoy in San Diego Harbor, with a light, number, and radar corner reflectors. File:Canbuoy11.jpg, Green can #11 near the mouth of the Saugatuck River. File:Can 11 in Saugatuck river.jpg, Same green can #11, on a NOAA nautical chart. File:Sea mark near Hurghada.JPG, Sea mark near Hurghada,

Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...

File:Enslinje - Ystad-2021.jpg, Triangular daymark in the marina of Ystad 2021.

References

External links

* {{DEFAULTSORT:Sea Mark Coastal construction Coastal fortifications Maritime signalling Nautical terminology Navigational buoys

Definitions

Image gallery

See also

Mark types

Other

References

External links