- Aid
To Navigation:
- United
States Coast Guard (USCG) term used to describe
any device used as an aid to navigation such
as lighthouses, range lights, buoys, etc.
- Astrigals:
- Vertical
or diagonal members that retain the glass
storm panels in the frame of the lantern room,
typically made of bronze.
- Chariot
Wheels:
- Brass
or steel wheels which act as the bearings
on which a rotating lens assembly rotates.
- Characteristic:
- The
timing of the flash/dark periods of light
output from a lighthouse. Lighthouses in a
given geographical area will each have a distinctive
characteristic so that a mariner may determine
which of the lights he is observing.
- Day
Mark:
- A
distinctive pattern painted on the exterior
of a lighthouse or other structure, used by
mariners to fix their position during daylight
navigation. In many cases, the lighthouse
structure itself is considered a daymark.
- Eclipse:
- The
dark period in a lighthouse flash characteristic.
- Fixed
Light:
- A
steady, non-flashing beam.
- Focal
plane:
- An
imaginary line drawn through the center of
the light source and the lens which defines
the center line of the beam and is used as
a reference to measure the height of the beam
above the adjacent body of water. Not to be
confused with the same term, used in photography,
to define the surface on which the image through
the lens is focused ie. the film surface.
- Fresnel
lens:
- A
system of annular prisms that refract and
reflect into a beam; invented in 1821 by Augustine
Fresnel; this system captures and focuses
up to 70% of the light emitted from the illuminant.
Fresnel designed a variety of lens system
sizes which he defined by orders. Today, there
are 9 modern equivalents to his original orders,
first through sixth (including a 3 1/2 order),
a meso radial, and hyper radial. The first-order
lens is the largest and is typically used
in coastal lights. The sizes of the lenses
and their effective range decrease as the
order number increases. Click
here for a more detailed description.
- Keeper:
- The
person in charge of maintaining the light
station and attending the light source and
the optic.
- Lantern
Room :
- The
portion of the lighthouse structure that houses
and protects the lens and light source; relative
size described/defined by the size of the
lens based on the 7 Fresnel orders.
- Lantern
Deck:
- Interior
deck in the lantern room that provides access
for maintenance and cleaning lens and rotating
mechanism.
- Lantern
Glass:
- Glass
panes in the lantern that protect the lens
and light source while allowing the maximum
amount of light to pass. Also referred to
as "lantern glazing."
- Lighthouse:
- The
building or structure, regardless of architectural
style, that includes or supports the lantern
room and lens and provides a fixed aid to
navigation located at some place important
or dangerous to navigation. The lighthouse
may be outfitted with foghorns, sirens, etc.,
by which ships are guided or warned.
- Light
Station :
- Refers
not only to the lighthouse but to all the
buildings in the complex necessary to support
the lighthouse including keepers quarters,
oil house, fog signal building, cisterns,
boathouse, workshop, etc.
- Lighthouse
Tender:
- Ship
used to supply the light and fog signal stations,
maintain buoys, and service lightships. Today,
similar vessels are called buoy tenders.
- Lightship:
- A
moored vessel displaying a light which marked
a harbor entrance or a dangerous projection
such as a reef where lighthouses could not
be constructed. The light characteristic displayed
is assigned to location, not the vessel.
- Oil
house:
- A
small building, usually made of stone or concrete,
which stored oil for lighthouse lamps. Oil
houses were built after kerosene, a highly
flammable agent, came into use as an illuminant.
- Range
lights:
- Pairs
of fixed aids that are typically used to guide
ships into or through channels; the lights
are typically defined by upper and lower positions;
when the lights are aligned as described in
the USCG light list, the mariner will know
his position relative to the channel.
- Screwpile:
-
A type of piling fitted with a helical fluke
that is twisted into the seabed. 2. A lighthouse
type that employs screwpilings as a primary
foundation system.
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