SHORT RANGE AIDS TO NAVIGATION
DEFINING SHORT RANGE AIDS TO NAVIGATION
500. Terms And Definitions
The term “short range aids to navigation” encompasses
lighted and unlighted beacons, ranges, leading lights,
buoys, and their associated sound signals. Each short range
aid to navigation, commonly referred to as a NAVAID, fits
within a system designed to warn the mariner of dangers
and direct him toward safe water. An aid’s function deter-
mines its color, shape, light characteristic, and sound. This
chapter explains the U.S. Aids to Navigation System as
well as the international IALA Maritime Buoyage System.
The placement and maintenance of marine aids to nav-
igation in U.S. waters is the responsibility of the United
States Coast Guard. The Coast Guard maintains lighthous-
es, radiobeacons, racons, Loran C, sound signals, buoys,
and daybeacons on the navigable waters of the United
States, its territories, and possessions. Additionally, the
Coast Guard exercises control over privately owned navi-
gation aid systems.
is a stationary, visual navigation aid. Large
lighthouses and small single-pile structures are both bea-
cons. Lighted beacons are called
; unlighted beacons
. All beacons exhibit a
sort. In the case of a lighthouse, the color and type of struc-
ture are the daymarks. On small structures, these daymarks,
consisting of colored geometric shapes called
often have lateral significance. Conversely, the markings
on lighthouses and towers convey no lateral significance.
501. Major And Minor Lights
Lights vary from tall, high intensity coastal lights to
battery-powered lanterns on single wooden piles. Immov-
able, highly visible, and accurately charted, fixed lights
provide navigators with an excellent source for bearings.
The structures are often distinctively colored to aid in iden-
tification. See Figure 501a.
is a high-intensity light exhibited from
a fixed structure or a marine site. Major lights include pri-
mary seacoast lights and secondary lights.
are those major lights established for mak-
ing landfall from sea and coastwise passages from headland
are those major lights estab-
lished at harbor entrances and other locations where high
intensity and reliability are required.
usually displays a light of low to mod-
erate intensity. Minor lights are established in harbors,
along channels, rivers, and in isolated locations. They usu-
ally have numbering, coloring, and light and sound
characteristics that are part of the lateral system of buoyage.
are placed where they will be of most use:
on prominent headlands, at harbor and port entrances, on
isolated dangers, or at other points where mariners can best
use them to fix their position. The lighthouse’s principal
purpose is to support a light at a considerable height above
the water, thereby increasing its geographic range. Support