Red buoy in San Diego Harbor. Note red light, number, radar reflecting corners and sea lion.

A sea mark is a pilotage aid which identifies the position of a maritime channel, hazard and administrative area to allow boats, ships and seaplanes to navigate safely. Image File history File links Download high resolution version (429x650, 57 KB)A sea lion on buoy number 14 in San Diego Bay - File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Download high resolution version (429x650, 57 KB)A sea lion on buoy number 14 in San Diego Bay - File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Pilotage is the use of fixed visual references on the ground or sea to guide oneself to a destination. ... From the latin maritimus, maritime refers to things relating to the sea. ... Lobster boat A boat is a watercraft, usually smaller than most ships. ... Italian ship-rigged vessel Amerigo Vespucci in New York Harbor, 1976 A ship is a large, sea-going watercraft, sometimes with multiple decks. ... A DeHavilland Single Otter floatplane in Harbour Air livery A seaplane is an aircraft designed to take off and land (correctly, though less commonly, alight) upon water. ...

There are two types of sea mark:

• posts - fixed to the seabed
• 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 locate channels, dangerous rocks or shoals, mooring positions, areas of speed limits, traffic separation schemes, submerged shipwrecks, and for a variety of other navigational purposes. Some are only intended to be visible in daylight (daymarks), others have some combination of lights, bells, horns, whistles and radar reflectors to make them usable in all weather conditions. The seabed is the bottom of the ocean. ... A sea lion on navigational buoy #14 in San Diego Harbor A buoy is a floating device that can have various purposes, which determine whether the buoy is anchored (stationary) or allowed to drift: The word is derived from the Dutch boei. sea mark - aids pilotage by marking a maritime... There are several meanings of float: an air-filled vessel that floats on water, such as some types of lifeboats buoyancy float (project management) floating currency floating exchange rate floating point, a datatype in computer science free float of company stock insurance (investable policyholder funds) root beer float: ice cream... The purpose of a ships or boats anchor is to attach the vessel to the ground at a specific point. ... A shoal is a sandbank or bar creating a shallow. ... A shipwreck is the remains of a ship after it has sunk or been beached as a result of a crisis at sea. ... A day beacon is an unlighted nautical navigational aid. ... Buoy in San Diego Harbor. ...

Marks are shown on nautical charts, using symbols that distinguish their colour, shape and light characteristic, and are often identified by name or number. A nautical chart is a graphic representation of a maritime area and adjacent coastal regions. ... A light characteristic is a coded description displayed on a nautical chart under the chart symbol for a lighthouse, lightvessel or sea mark with a light on it, to indicate how that light is recognised visually and audibally. ...

The International Association of Lighthouse Authorities defines two systems of marks specifying the shapes, colours and characteristic lights of buoys depending on their purpose. For historical reasons, there are unfortunately two contradictory systems of lateral marks in use: International Association of Lighthouse Authorities (or IALA for short) is a non-profit organization founded 1957 to collect and provide nautical expertise and advise. ... In geometry, objects are of the same shape if one can be transformed to another by dilating (that is, by multiplying all distances by the same factor) and then, if necessary, rotating and translating. ... Color is an important part of the visual arts. ... A light characteristic is a coded description displayed on a nautical chart under the chart symbol for a lighthouse, lightvessel or sea mark with a light on it, to indicate how that light is recognised visually and audibally. ... A lateral buoy, lateral post or lateral mark, as defined by the International Association of Lighthouse Authorities, is a sea mark used in maritime pilotage to indicate the edge of a channel. ...

• IALA System B in the Americas, the Philippines and Japan
• IALA System A everywhere else.

The two systems differ principally in the colours used to denote the two sides of a channel. When approaching a harbour from seaward, System A places conical green marks to starboard and cylindrical red ones to port. In System B these are replaced with conical red marks to starboard and cylindrical green ones to port. This can be remembered (for System B) with the mnemonic "Red, right, return". Another System 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. The Americas (sometimes referred to as America) is the area including the land mass located between the Pacific Ocean and the Atlantic Ocean, generally divided into North America and South America. ... Starboard is the nautical term (used on boats and ships) that refers to the right side of a vessel, as perceived by a person facing forward (i. ... Port is the nautical term (used on boats and ships) that refers to the left side of a ship, as perceived by a person facing towards the bow (the front of the vessel). ... The Mnemonic acronym system is a technique which uses a stored phrase to recall a list of items, often in a certain order. ...

See also: lightvessel, lighthouse, landmark A disused lightvessel docked in Rotterdam, Netherlands. ... The Peggys Point lighthouse in Nova Scotia, Canada An aid for navigation and pilotage at sea, a lighthouse is a tower building or framework sending out light from a system of lamps and lenses or, in older times, from a fire. ... For the legal term denoting a ruling or law of great import, see landmark case For the former Las Vegas hotel and casino, see The Landmark Hotel and Casino. ...