The art or science of determining the ship’s or aircraft’s position and of conducting a ship or aircraft from one position to another. The problems of navigation are those of position, direction and distance

a method of navigation by which the position of the ship is calculated from the direction and rate of progress through the water from the latest well- determined position.

near-shore navigation method by which the movement of a ship is directed by reference to landmarks, navigational aids or soundings.

a method of navigation which employs the use of various electronic devices. It differs from piloting primarily in the manner of collecting information.

the position of the ship is determined by the observation of celestial bodies such as the sun, moon, planets and stars.

the planet with which we are most familiar, although it is approximately an ablate spheroid, for navigational purposes, it is assumed to be a true sphere.

6,864.57 nautical miles;

6,887.91 nautical miles or a

23.34 nautical miles

the diameter about which the earth rotates. The north end is the north pole while the south end is the south pole.

a circle on the surface of the earth, the plane of which passes through the center of the earth.

a circle on the surface of the earth, the pale of which does not pass through the center of the earth.

the great circle which is equidistant to the poles. The plane is perpendicular to the surface of the earth’s axis.

small circle on the surface of the earth having planes parallel to the plane of the equator and perpendicular to the earth’s axis.

great circle on the surface of the earth that passes through the poles.

meridians used as the origin of measurement of longitude, the meridian of Greenwich England.

the angular distance between the position and the equator measured northward or southward from the equator along a meridian and labeled as appropriate N or S.

the angular distance between the position and the prime meridian measured either eastward or westward from the prime meridian along the area of the equator to the meridian of the position in degrees from 0 – 180 deg and labeled E or W.

angular inclination of that line to the meridian measured right or counter clockwise from the north point of the meridian and expressed in three digits.

as applied to marine navigation, is the intended direction of travel of a ship through the water

the direction in which the ship point or heads at a given time.

the direction of a terrestrial object from the observer; azimuth as applied to the celestial bodies.

the length of a line joining two places on the surface of earth and is expressed in nautical miles. The shortest distance between two points on the surface of the earth is along the great circle joining them.

the velocity of travel and is expressed in knots. One (1) knot is equal to 6,080.2 feet per hour. One (1) minute of angular measurement in great circle for navigation purpose, is also equals to 2,000 yards.

any device external to a vessel or aircraft intended to assist a navigator to determine his position or safe course or to warn him from danger or obstruction to navigation.

the primary functions is to warn of some danger or to delineate channels.

built up of steel plates having the shape of a tin cylinder used to mark left side of the channel from seaward.

built up of steel plates, the above water portion having the shape of truncated cone, cone in shape used to mark right side of the channel from seaward.

steel floats with a flat top on which a framework containing a bell is mounted. Most bell buoys are sounded by the motion of the sea and struck by compressed gases or electrically operated hammer.

slightly tapering pole or spar frequently used to mark side of channel. May replace the nun or can buoys.

similar in construction to bell buoy but has four (4) gongs each of different tones.

provides a sound signal which is useful at night and also during fog and low visibility; cone in shape with a whistle, sounded by the motion of the sea.

having batteries or gas tanks. Framework supports the light. A metal float on which is mounted a short skeleton tower.

lights and sound signals are combined, such as lighted bell buoys, lighted gong buoys and a lighted whistle buoy.

radar reflectors which return a strong echo to the radar screen are fitted on many buoys of all types.

it is a man made permanent fixture having a light of certain characteristics and is usually watched.

such as Floating lighthouses that mark approaches or entrances to harbors. b. Used when building a permanent structure is impractical.

similar to lighthouses and generally unwatched.

lighted floating marker.

continuous steady light.

shows single flash at regular interval, the duration of light always shorter than the duration of darkness not more than 30 flashes per minute.

shows groups of two or more flashes at regular intervals.

shows not less than 60 flashes per minute.

shows quick flashes for about 4 seconds followed by a dark period of about 4 seconds.

shows short flashes of about 0.4 second followed by a long flash of about 4 seconds in duration.

a light with a group of 2 or more eclipse.

Standard Colors of Lights

range of visibility

depends on the tendency of a pendulous gyroscope to seek to along its axis with that of the earth.

located at various positions throughout the ship to indicate the master gyro heading.

a non-magnetic ring formed to feet snugly over the compass bowl about which it can be turned to any desired direction. used to determined bearings of terrestrial objects.

similar to the bearing circle with a special attachment for observing the sun. used to determine bearings of celestial bodies.

consists of a compass stand, compass bowls and compass card. used also in determining bearing.

an azimuth circle having a telescopic sight mounted over it.

used to find range of objects of known height or height of objects of known distance.

weight attached to a marked line from 7 to 14 lbs.

from 30 to 100 lbs.

works under water pressure.

works under speed of sound.

receives signals and weather information.

receiver and a loop antenna which has directional properties.

used for obtaining bearings and ranges of objects in all conditions of visibility.

measures the difference in the time reception of two synchronized radio signals which is used to determine a hyperbolic line of position.

uses speed of sound under water. It gives bearing and distance of objects underwater.

measuring angular heights of celestial bodies and measuring angles between two visible objects.

accurate clock of superior construction for maintaining accurate time aboardship.

ordinary clock set to keep standard or zone time.

used for timing celestial observation.

useful in piloting for identification of lights and in celestial observation.

provides the navigator with positions of the celestial bodies relative to the position of the observer.

soft lead pencil with eraser.

contains drawing compass dividers, screwdrivers etc.

for drawing a straight line in plotting direction.

measuring directions.

for measuring angles.

for transferring lines from compass rose to any place on the chart or vice versa

atmospheric pressure (Mercurial or Anenoid)

determines temperature.

measure relative humidity.

measure wind direction and wind speed.

a pictorial representation of the earth surface or part of it with provision for determining position, distance and direction and information of interest to the navigator. This shows usually coastal areas of water and gives a great deal of hydrographic information which is useful to the navigator.

for most part shows land areas including their political subdivision and topography.

methods of representing the curved surface of the earth on a flat surface.

system of lines that indicates extent of fairways and restricted waters

(depth of water) numbers scattered on water areas of the charts. Sounding can be either in feet or fathoms and can be determined from the title of the charts.

indicated on the charts by a red color or star. Characteristics and features near the symbols.

opal or red colors other than black solid shape for black vertical stripes and horizontal stripes, lighted red/gray.

used to measure directions. Outer indicates true direction, the inner indicates magnetic directions and it also gives variation to locality.

rows of fine dots.

Small circles

irregular shapes

numbers in feet above high water

a compass that measures the direction by means of the principles of gyroscopic inertia and precision.

a compass on its directive force upon the attraction of the magnetic poles of the earth

may also be treated as a compass due to its parts. The compass card is driven through synchro system which receives an electrical input from the Master Gyro.

direction of terrestrial object from observer, azimuth as applied to a celestial body.

position obtained from lines of position taken at the same time or the intersection of two (2) or more lines of position taken simultaneously.

a line on some point of which the ship is located. This is established by the following means:

if two objects appear to be in line as seen from the ship, the ship must be along this line.

if the direction of the known object is sighted from the ship, it must be along this line.