This document defines various nautical terms related to navigation and seamanship. It provides definitions for 60 terms, including azimuth, altitude, anchor, anchorage, bearing, binnacle, bulwark, bilge, breeches buoy, cardinal points, chart, course, dead reckoning, echo gram, fathom, fetch, fix, flare, ground tackle, gyro compass, heading, knot, latitude, lee side, lighthouse, log, longitude, luber line, magnetic compass, mayday, medevac, meridian, navigation, pelorus, piloting, plot, running fix, rhumb line, seamansship, true wind, and underway. The terms cover topics like celestial navigation,

1. FS-313: NAVIGATION ANDSEAMANSHIP
S.NO: TERMS: DEFINITION:
1) AZIMUTH: An instrument used to determine the altitude of celestial objects
before the introduction of the sextant , the first recorded use by
Greek astronomers in around 200 BC.
2) ALTITUDE: The angular distance of a celestial body above the viewers horizon.
3) AGROUND: Resting on or touching the ground or bottom.
4) ANCHOR: An object designed to prevent or slow the drift of a ship, attached to
the ship by a line or chain; typically a metal, hook like, object
designed to grip the bottom under the body of water.
5) ANCHORAGE: A suitable place for a ship to anchor. Area of a port or harbor.
6) BEARING: The compass reading taken of a object in relation to the observer.
7) BINNACLE: The stand on which the ship's compass is mounted.
8) BULWARK: The extension of the ship's side above the level of the weather deck.
9) BILGE: The lowest inner part of a ships hull. bilge water accumulates in the
bilge.
10) BREECHES BUOY: used to transfer person from a disable ship to either rescue ship or
to shore
11) CARDINAL
POINTS:
The four main parts of the compass, North, South, East, West.
12) CARDINAL
POINTS:
Buoyage marks indicating the direction of safe water with reference
to the cardinal points.
13) COMPASS
ERROR:
The angular difference between true north and compass north.
14) CHART: A map of the sea , showing any coastal lines and used specifically for
nautical navigation.

2. FS-313: NAVIGATION ANDSEAMANSHIP
15) COURSE: horizontal distance in which a vessel is steered or intended to be
steered.
16) DUNNAGE: Loose packing material used to protect a ship's cargo from damage
during transport. Personal baggage.
17) DEVIATION: The angular difference between compass north and magnetic north.
18) DOCKING: The procedure for coming alongside and securing to a wharf or jetty.
19) DEAD
RECKONING:
Is fixing of present position or expected future position, from a
previous position using known direction and distances.
20) EQUATOR: The great circle whose plane is perpendicular to the polar axis,
midway between the poles.
21) ECHO GRAM: Visual record of reflected echoes of sound transmitted by an echo
sounder
22) FATHOM: A unit of measure equal to six feet, used to describe depth of water,
or length of rope or line.
23) FETCH: The distance over water which the wind has blown uninterrupted.
24) FIX: A relatively accurate position determined without reference to any
former position.
25) FLARE: A signal device to indicate distress, the external concave curve of
the bow of a ship
26) GROUND
TACKLE:
A collective term used to embrace all of the gear used for anchoring
or for securing a navigation buoy to the bottom.
27) GYRO COMPASS: A directional instrument that indicates gyro north, which can be
very close to true north.
28) GALLEY: The kitchen in a ship or aircraft.
29) HEADING ( SHIPS
HEAD)
Is constantly changing value as ship oscillates or yaws across due to
effects of sea & steering error.(or) the direction in which the ships
head is pointed.
30) HALYARD: A rope used for hoisting sails, spars or flags.

3. FS-313: NAVIGATION ANDSEAMANSHIP
31) KNOT: A unit of speed equal to one nautical mile per hour.
32) KELLET: A heavy weight attached in the length of the anchor rope to reduce
the angle of pull on the anchor.
33) LATITUDE: The angular distance of a point on the surface of the earth north or
south of the equator as measured at the centre of the earth.
34) LEE SIDE: The side opposite to the direction from which the wind blows.
35) LIGHT HOUSE: A major light built as a manmade aid to navigation; may be manned
or unmanned.
36) LOP(LINE OF
POSITION):
A line on the chart along which the vessel is known to lie.
37) LOG: A device that measures distance travelled through the water, from
which speed can be calculated.
38) LONGITUDE: The angular distance east or west of prime meridian of the prime
meridian of a point on the surface of the earth as measured at the
polar axis.
39) LUBBER LINE: The reference line of a compass.
40) MAGNETIC
COMPASS:
A directional instrument actuated by the earths magnetic field.
41) MAY DAY : Mayday is an emergency procedure word used internationally as a
distress signal in voice procedure radio communications.
42) MEDEVAC: Includes evacuation of a person from a vessel for medical reasons.
43) MERCATOR
PROJECTION:
The most common type of chart projection used for navigational
charts.
44) MERCATOR
CHART:
A cylindrical map projection in which the meridian and parallel
appear as lines crossing at right angles and in which areas appear
greater farther from the equator.
45) MERIDIAN: An imaginary line joining the earths poles ,the prime meridian is the
one that passes through Greenwich, England and represents zero
longitude.
46) MAST HEAD
LIGHT:
white light placed at centre over an arc of horizon of225deg
&22.5deg abaft the beam on either side.

4. FS-313: NAVIGATION ANDSEAMANSHIP
47) NAVIGATION: process of directing or conducting the movement of a vehicle
/vessel from one place to another safely.
48) PELORUS: The navigation instrument used for taking visual bearings, having a
card and an arc rotating sight bar with two sighting vanes.
49) PILOTING: Is navigating, using fixed points of reference on the sea or on land ,
usually with reference to a nautical chart or aeronautical chart to
obtain a fix of the position of the vessel or aircraft with respect to a
desired course or location.
50) PLOT: To draw lines on a chart indicating bearings, courses and positions.
51) RUNNING FIX: A position determined by the use of bearings that have an
appreciable time difference in between them.
52) RHUMB LINE: a line crosses every meridian of sphere at same angle.
53) STERN LIGHT: white light, unbroken over an arc of horizon of 135deg &67.5deg
each side.
54) SIDE LIGHT: green light, unbroken over an arc of horizon of 112.5 deg&52.5deg
abaft the beam.
55) SKIPPER: The person in command of a vessel.
56) SEMAPHORE: Signalling by hand flags or arms.
57) SEASMANSHIP: The skill , techniques ,or practices of handling a ship or boat at sea.
58) TRUE WIND: The direction and velocity of the wind as observed from a stationary
point
59) UNDERWAY: A vessel when not at anchor, aground or made fast to shore.
60) VARIATION: The angular difference between magnetic north and true north.