Types of Lights and Light Structures, Continued
Figure 4-5. Typical lighthouses.
For many years, lightships were used to mark offshore dangers or mark
the entrances to important harbors. Today, however, lightships are no
longer used in the United States. Instead, they have all been replaced by
light towers or large navigational buoys (LNBs) which, especially in the
case of the LNB, are much more economical to maintain.
A typical tower deckhouse is 60 feet above the water, 80 feet square,
and supported by steel legs in pilings driven nearly 300 feet into the
ocean bottom. Though once manned, these light towers are now
automated. The light tower has a helicopter landing deck and houses
equipment such as a radiobeacon, RACON, fog signal, and
communications equipment. On one comer of the deckhouse is a radio
tower supporting the radiobeacon antenna and a powerful light. At an
elevation of 125 feet above the water, the light is visible for over 20
miles. Although construction details of other towers vary slightly, they
are of the same general type.