A logical structure for the definition of terms describing some navigational aids has been developed and explicitly defined as in Figure 1. The main points are as follows:
The navigational aids discussed are beacons, rather than GPS receivers, sextants, maps, charts or lists of lights.
Those beacons that are navigational aids can be classified as built (implicitly assumed to be on land) and those that are floating (implicitly assumed to be moored in water at a fixed position).
The next subdivision is between those that are lit and those that are unlit.
Lighthouses fall into the ‘built and lit’ division, distinguished from lightstructures by the definition proposed above that includes a definition of the type of structure.
Daymarks fall into the ‘built and unlit’ category
Of the floating navigational aids, those that bear lights can be separated into Lightships, LANBYs, Lightfloats and lightbuoys.
Unlit floating navigational aids are buoys or marks.
It has been argued that the long history of navigational aids has resulted in an inconsistent use of certain terms and that difficulties arise when attempting to build logical structures to contain database information. Adopting a revised system of nomenclature solves the problems raised when attempting to classify navigational aids in a logical system. It is accepted that complete agreement of all interested parties over such a scheme will never be possible, but that the proposed system does at least offer the prospect of consistent data when shared between those who agree to use it.
The author expresses his thanks to Jim Slechta for inspiring him to write this paper. A particular debt of gratitude is owed to Michel Forand for his many constructive suggestions.