Navigation

3 satellites give

2 dimensional fix

standard distance

500 yds between small ships (<450 feet); 1,000 yds between large ships

watch circle

= mooring lengths; buoys can be expected to move within this region

IALA

International Association of Lighthouse Authorities

IALA region B Green

PORT; odd #s

Gain Control

Radar control used to increase or decrease the sensitivity of the radar receiver

IALA region B Red

STBD; even #s

master control station

Schriever AFB CO

JOTS (joint operational tactical system)

US fleet intelligence exchange system, real-time

letting-go bearing (drop bearing)

a bearing drawn from the intersection of the letting-go circle with the approach track to a convenient landmark or nav. aid, generally selected near the beam

triangulation

a calculation that measures the distance between satellites in orbit and the receivers on earth; intersections determines receiver position

form 1

a column formation of ships that take station in order of how they are sequenced in a FLTAC signal passed by the OTC

range selector

a control for selecting the range settings for the radar indicator

line of bearing

a line that ships form on either a specific true or relative bearing other than directly astern/ahead/abeam

turn (turn together)

a maneuver to alter course so that all of the ships company will have the same true position upon completion of the maneuver

guide

a ship on which the other ships take station when forming or maintain their station when formed

ionispheric corrections

a technique that reduces radio degredation in order to provide better accuracy

INS (inertial navigation system)

accurate, all weather self-contained nav. system, provides dead reckoning positions

acquire

allows operator to individually select one contact at a time

4th satellite gives

altitude

AN/SRN-25 (radio navigation set)

an automated navigation system that provides continuous and accurate ship positioning from GPS data

FOM (figure of merit)

an internal GPS receiver calculation that indicates the best accuracy achievable from the satellites being tracked

formation

an ordered arrangement of 2 or more ships who are sailing together

variation

angular difference between the true meridian and magnetic meridian

Aid to Navigation

any device external to a vessel that is intended to assist a navigator to determine position or safe course, or to warn of dangers and obstructions to navigation

ECDIS (electronic charting display information system)

approved charting system that satisfies requirements of IMO SOLAS convention

PPS (precision positioning service)

broadcasts on 2 generic frequencies (DoD&allies)

Standard positioning service (SPS)

broadcasts on one generic frequency (civilian)

Electronic charting system (ECS)

commercial charting system that does not satisfy requirements of the IMO SOLAS convention

steering compass

compass used by the helmsman or autopilot regardless of type

degaussing purpose

counteract the ship's magnetic field

frequency

cycles per second

red sector light

danger area

eclipses

dark intervals

Range Scale

defines distance from center of the display area to the bearing scale on the outer edge of the screen

deviation

deflection R or L of the magnetic meridian caused by magnetic properties of the vessel

general direction

determined by authorities following a clockwise direction around continental land masses

repeater error

difference between gyro repeater and master gyrocompass

compass error

difference between true heading and compass heading

Gyrocompass error

difference between true heading and gyrocompass heading

Raster Chart

digitalized picture of a chart

isolated danger marks

directly on or over dangers

interval

distance between lines of a formation

NAVSSI ( navigation sensor system interface)

distribute common position, velocity, time, and almanac data to onboard command and control and combat systems

magnetic poles

don't align exactly with true poles, position changes slightly every year

radio beacons

emit a distinctive signal on a specific frequency and when used with a direction finding receiver will yield a LOP

NAVDORM

establishes guidelines for the "features" and "profiles" settings of ECDIS-N

Daymarks

fixed structures that mark hazards or channels, may have fog signal that sounds during low visibility

isophase light

flashes at regular intervals; duration of light = duration of dark

flashing light

flashes on and off at regular intervals; duration of light < duration of darkness

buoys

floating aids moored to the seabed by sinkers with chain or other moorings of various lengths, variety of purposes

Control Segment

global network of ground facilities that track satellites, monitor transmissions, perform analysis, send commands and data to satellites

white sector light

good water

Major Light

high-intensity and reliable light exhibited from a fixed structure or marine site

lateral marks

indicate PORT and STBD side of channels

occulting light

light totally eclipsed at regular intervals; duration of light > duration of darkness

sector lights

lights used to warn the navigator of hazards to navigation when approaching from certain dangerous arcs/sectors by varied colors

line abreast

line that ships form on directly abeam of the guide

Minor Light

low to moderate intensity light used to mark a specific channel or location

Space Segment

made up of 31 satellites; allows for precision timing, broadcast signals, accuracy

digital flux gate magnetic compass (DFGMC)

magnetic compass over helm console, influenced by large changes in ships magnetic field

Secondary Major Light

major light established at harbor entrances

Primary Major Light

major light established for making landfall from sea

corpen (wheel)

maneuver to alter course so all the ships have the same relative position

electro magnetic log

measures the speed of a vessel through the water

safe water marks

mid-channel buoys

head bearing

nav. aid or GPS point on approach track usu. radio tower or water tank

ECDIS-N

navy version of ECDIS that plots fixes, tactical ocean data function, CO approval function; legal equivalent of a paper chart

Vector Chart

organizes data into separate layers that can be layered

Range Lights and Markers

pairs of nav aids, either lighted or unlighted, when aligned mark a channel; 2 fixed structures or lights usually located some distance apart; visible day and night

precision anchorage

pre-selected anchorage position; within 100 yes of intended drop point

AIS ( automatic ID system)

provides surface vessels with counter intelligence

special, information, or regulatory marks

purpose referenced on chart or other nautical docs

electronic bearing line (EBL)

radar control that allows a bearing between 2 objects on the radar display to be determined

Fast Time Constant (FTC)

radar control used to control rain or precipitation clutter from more than 3 nm from own ship

sensitivity time constant (STC)

radar control used to control sea clutter; effective within 3 nm of ownship

Variable Range Marker (VRM)

radar control with single ring with an operator-defined radius used to measure distance between 2 pts

drag circle

radius = distance from anchor to pelorus

swing circle

radius = length of ship + length of chain veered out

user segment

receive and process information into 3D coordinates

Maritime buoyage systems and IALA

region a, region b

code division multiple access (CDMA)

satellites use common carrier frequencies while allowing the receiver to determine which satellite is communicating

range circles

semicircles plotted on the approach track measured from the center of the drop circle (100yd increments up to 1,000 then 1,200; 1,500 ; 2,000)

column formation

ships are formed directly ahead or astern of the guide

cardinal marks

shows us where navigable water lies; not used by US except great lakes

racon

signals usually on lights or buoys that are triggered by a ship's radar and appear as a symbol on the radar screen

magnetic meridian

skewed from the true meridian because of irregularities in the Earth's core

distance

space in yds between ships in a formation

Daybeacons

stationary visual navigational aids, unlighted

local direction

taken when approaching harbor, river, etc from seaward

approach track

the course a ship must follow to arrive at the center of the anchorage

letting-go circle (drop circle)

the location where the anchor is to be dropped; radius =distance between hawsepipe and pelorus

datum

the mathematical model of the earth that we use to calculate position coordinates, heights, and distances; the origin and orientation of the coordinate system used on a chart

VMS (voyage management system)

the only approved ECDIS system for US Navy vessels

monitor stations

track GPS satellites as they pass overhead and pass their information to the master control station

green sector light

turning points or best water areas

Sea and anchor detail

used for entering and leaving port or conducing a precision anchorage, full nav. team and additional personnel

ground antennas

used to communicate with the GPS satellites

precession

when a force is applied to change alignment of the spin axis of the gyrocompass; resultant motion perpendicular to force

pivot ship

wing ship in maneuver