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Subject: Silicon Sea Glossary
From: Dan Hogan (dhhogan1@XXX.XXX)
Date: Mon Sep 16 2002 - 16:28:28 EDT
Silicon Sea Navigation Glossary --08/04/2001
The following is the glossary of the navigation terms as they are used within
the Silicon Sea navigation problems. They follow nautical tradition except
where brevity or restrictions of using internet mail (ASCII)have required
changes. Also some were arrived at by previous discussions on Navigation-L.
Bearing= The reading of a compass, handbearing/ships, taken to an object.
Body= A celestial object.
CC= Compass Course/Course-to-Steer, the TC corrected for current,
variation, and deviation.
CMG= Course Made Good.
D= See Dist.
Dist= distance in nautical miles.
DR= dead reckoning, calculated by a Sailings method as:
Distance = Time X Speed.
Drift= the speed of the current.
a)Early were lessons in miles per day(24Hrs)
b)Current custom is in Kts.
ENT= Evening Nautical Twilight
EP= Estimated Position, the DR plus the effects of current.
ETA= estimated time of arrival.
FIX= A position fix, by celestial or land bearings to a known point.
GHA= Greenwich Hour Angle
HE= Height of the eye or an object above sea level. Used to calculate
distance to the horizon or an object.
Hs= Sextant altitude, altitude of a body directly measured with a sextant.
No corrections are applied.
Kts= nautical miles per hour (speed).
Log= a) The book that a navigator records his calculations and
observations.
b) An instrument with a trailing spinner used to calculate the
distance traveled through the water.
LOP= A line of position, by celestial or a line derived from a bearing to
a known point, the ship's true position must be somewhere on, or
close to, the line.
MNT= Morning Nautical Twilight
mtrs= Meters
NA= Nautical Almanac.
Nmi/Nm= nautical miles.
Plotting Sheet= Any paper used by a navigator to graph his LOP's and
ships course.
RFIX= a Running FIX, is a previous line of position brought forward to a
current line of position.
S= Speed in Kts, usually calculated or from a Knotmeter.
Sailings= DR techniques such as Plane Sailing, Mid-Latitude Sailing,
Mercator Sailing, Great Circle Sailing, etc.
Set= The direction *toward* which a current is moving.
SMG= Speed Made Good over the ground.
SR= Sunrise
SS= Sunset
T= Time, the time of an event that is recorded, usually in a log.
TC= True Course, plotted or calculated for a mercator chart from point A
to point B.
UT= Universal Coordinated Time, the time from NIST broadcast by WWV. Same
as GMT, Zulu, UTC.
ZT= Zone Time, the time on the meridian of a vessel's either DR or FIX, the
longitude DR/FIX divided by 15.
Dan Hogan WA6PBY
C27 "Gacha"
dhhogan1@XXX.XXX
Nav-L Page: http://www.wa6pby.com
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