Greenwich hour angle of the mean sun, expressed
in time units plus 12 hours.
GUIDEVessel designated in a formation or disposition
as the one for others to keep station on.
GUN SALUTEBlank shots fired to honor a
dignitary or in celebration.
H-HOUR The term used to designate the time for
an operation to commence.
HEAD-ON VESSELOne vessel meeting another
on a reciprocal or nearly reciprocal course
involving risk of collision.
HOISTTo move an article vertically upward by
means of some hoisting rig.
HULL DOWNSaid of a vessel when, because of
distance and curvature of Earth, only the
superstructure is visible.
INFRARED Transmission of signals by light
outside the visual spectrum. This method, which
may be directional or nondirectional, necessitates
the use of special equipment and affords greater
security than normal visual means.
IRISH PENNANTA loose end of line carelessly
JANAPJoint Army-Navy-Air Force Publication.
LATITUDEDistance north (N) or south (S) of the
equator, expressed in degrees and minutes.
LONGITUDEDistance east (E) and west (W) of the
prime meridian, which runs through Greenwich,
LORANAn electrical navigation system by which
hyperbolic lines of position are determined by
measuring the differences in the time of reception
of synchronized pulse signals from two fixed
MANEUVERING BOARDA polar coordinated
plotting sheet devised to aid in the solution of
problems involving relative movement.
MASTHEAD LIGHTThe white running light
placed over a vessel's fore-and-aft centerline
showing an unbroken light over an arc of the
horizon of 225°, fixed to show the light from right
ahead to 22.5° abaft the beam on either side of the
MEAN TIMETime based upon the rotation of
Earth relative to the mean sun.
MERCATOR PROJECTION A conformal
cylindrical map projection in which the surface of
a sphere or spheroid, such as Earth, is conceived
on a cylinder tangent along the equator.
MESSENGER(l) A line used to haul another
heavier line across an intervening space; (2) One
who delivers messages.
NEED-TO-KNOW A criterion used in security
procedures that requires the custodians of
classified information to establish, prior to
disclosure, that the intended recipient must have
access to the information to perform his/her
NIGHT VISION DEVICESPrecision instruments
that use electronic optics for observation,
surveillance, and navigation. Also referred to as
NTPNaval Tactical Publication.
NWPNaval Warfare Publication.
OCCULTING LIGHTSA navigational aid in
which the period of light is equal to or more than
the period of darkness.
OCCUPATIONAL STANDARDSThe minimum
requirements for enlisted occupational skills of a
certain rate or rating.
OFFICIAL INFORMATIONInformation that is
owned by, produced by, or subject to the control
of the United States Government.
OFFICIAL VISITA formal visit of courtesy
requiring special honors and ceremonies.
OMEGA An electronic navigational system.
PELORUSDevice for taking relative bearings.
PERSONNEL QUALIFICATION STANDARDS
Qualification for officers and enlisted personnel
to perform certain duties.
PHYSICAL SECURITYThat part of security
concerned with physical measures designed to
safeguard personnel; to prevent unauthorized
access to equipment, installations, material and
documents; and to safeguard them against
espionage, sabotage, damage, and theft.
POSITION ANGLEThe number of degrees an
object seen in the sky is above the horizon.
POWER-DRIVEN VESSELAny vessel propelled