Beacon
Basics
A beacon is a prominent specially constructed object forming a conspicuous mark as a fixed aid to navigation or for use in hydrographic survey (IHO Dictionary, S-32, 5th Edition, 420).
A lateral beacon is used to indicate the port or starboard hand side of the route to be followed. They are generally used for well defined channels and are used in conjunction with a conventional direction of buoyage. (UKHO NP 735, 5th Edition) Isolated danger and cardinal beacons indicate where the mariner may find the best navigable water.
Different to a buoy which is a floating object, a beacon is fixed on the ground
Gallery
Data Model
The Proposal here in the OSM-WIKI is located at Proposed_features/marine-tagging#Buoys_and_Beacons
Tags to be used for adding beacons to OpenSeaMap are found here: Beacon Data Model.