Editing Lateral mark (section)

{{short description|Sea mark marking the edge of a channel}}
[[File:Visual Aid to Navigation Guide - Region B - Day.svg|thumb|400px|Visual buoyage, Region B, by day]]

A '''lateral [[buoy]]''', '''lateral post''' or '''lateral mark''', as defined by the [[International Association of Marine Aids to Navigation and Lighthouse Authorities]], is a [[sea mark]] used in maritime [[pilotage]] to indicate the edge of a [[channel (geography)|channel]].

Each mark indicates the edge of the safe water channel in terms of [[port (nautical)|port]] (left-hand) or [[starboard]] (right-hand). These directions are relative to the ''direction of buoyage'';  this is usually a nominally [[Source (river or stream)|upstream]] direction. In a river, the direction of buoyage is towards the river's source; in a harbour, the direction of buoyage is into the harbour from the sea.  Where there may be doubt, it will be labelled on the appropriate [[Nautical chart|chart]]. Often the [[cardinal mark]] system is used instead when confusion about the direction would be common.

A vessel heading in the direction of buoyage (e.g. into a harbour) and wishing to keep in the main channel should:
* keep [[port (nautical)|port]] marks to its port (left) side, and
* keep [[starboard]] marks to its starboard (right) side.