A Special Mark, as defined by the

International Association of Lighthouse Authorities The International Organization for Marine Aids to Navigation (IALA), previously known as International Association of Lighthouse Authorities, is an association founded in 1957 to collect and provide nautical expertise and advice. IALA is also kn ...

, is a sea mark used in maritime

pilotage Piloting or pilotage is the process of navigating on water or in the air using fixed points of reference on the sea or on land, usually with reference to a nautical chart or aeronautical chart to obtain a fix of the position of the vessel or air ...

. It is recognisable by its yellow colour and X, (also referred to as a St. Andrews Cross or

saltire A saltire, also called Saint Andrew's Cross or the crux decussata, is a Heraldry, heraldic symbol in the form of a diagonal cross. The word comes from the Middle French , Medieval Latin ("stirrup"). From its use as field sign, the saltire cam ...

) top-mark. It has a distinctive sequence of various flashes that does not match any other navigational mark flashes in its vicinity.

Purpose

Special marks can indicate: *

Administrative area Administrative divisions (also administrative units, administrative regions, subnational entities, or constituent states, as well as many similar generic terms) are geographical areas into which a particular independent sovereign state is divi ...

s * Water skiing areas * Anchorage areas * Mooring areas *Waiting areas * Marine farms *

Oil well An oil well is a drillhole boring in Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is released as associated petroleum gas along with the oil. A well that is designed to produce only gas m ...

s * Dead ends *

Pipelines A pipeline is a system of pipes for long-distance transportation of a liquid or gas, typically to a market area for consumption. The latest data from 2014 gives a total of slightly less than of pipeline in 120 countries around the world. The Un ...

*Spoil ground (an area where dredged material is deposited) *Historic wrecks *Protected areas * Outfall pipes (such as

Stormwater Stormwater, also written storm water, is water that originates from precipitation (storm), including heavy rain and meltwater from hail and snow. Stormwater can soak into the soil ( infiltrate) and become groundwater, be stored on depressed lan ...

, and

Cooling water Cooling tower and water discharge of a nuclear power plant Water cooling is a method of heat removal from components and industrial equipment. Evaporative cooling using water is often more efficient than air cooling. Water is inexpensive and no ...

) * Sewerage pipes * Intake pipes *

Submarine cable Submarine cable is any electrical cable that is laid on the seabed, although the term is often extended to encompass cables laid on the bottom of large freshwater bodies of water. Examples include: *Submarine communications cable *Submarine power ...

Other uses

Buoys A buoy (; ) is a floating device that can have many purposes. It can be anchored (stationary) or allowed to drift with ocean currents. History The ultimate origin of buoys is unknown, but by 1295 a seaman's manual referred to navigation buo ...

, such as a

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, whil ...

or Mooring buoy are coloured yellow or have a yellow light to indicate it is not an aid to navigation.

References

* {{DEFAULTSORT:Special Mark Navigational buoys

Purpose

Other uses

See also

References