Aid to Navigation (Discontinued)
The use of the definitions below has been discontinued since they were in conflict with the current definition of the term Aid to Navigation given in the IALA Constitution (2016).
Please find the current definition here.
Alternative term: Seamark (G.B.)
Visual, acoustical or radio device to assist the safe and easy movement of ships.
Note: The term "seamark" is most commonly used for a visual device.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
Any device or system, external to a vessel, which is provided to help a mariner determine position and course, to warn of dangers or of obstructions, or to give advice about the location of a best or preferred route.
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM
centre of gravity
Centre of buoyancy
Vessel Traffic Services