NAV Final

Nautical Charts

Graphic representations for marine navigation, available in digital or hard copy form.

Course

Intended horizontal direction of a vessel, measured clockwise from north at 000° through 360°.

Heading

Direction a vessel points at any moment, expressed as angular distance from 000° through 360°.

Bearing

Direction from one terrestrial point to another, expressed as angular distance from 000° through 360°.

Speed

Rate of motion, typically measured in knots (1 NM per hour).

Lines of Position (LOP)

Lines on a chart indicating a vessel's position, obtained from visual aids, RADAR, or celestial sights.

Fix

Position derived from intersecting three or more LOPs.

Prime Meridian

Base line of longitude, measured from True North to True South.

Longitude

Angular distance from the Prime Meridian, measured 000°-180° East or West.

Equator

Great circle at latitude 0° dividing the Northern and Southern Hemispheres.

Latitude

Angular distance from the Equator, measured north or south from 000°-90°.

Rhumb Line

Line with constant bearing relative to true north.

Great Circle Line

Circular intersection of a sphere and a plane passing through its center point.

Dead Reckoning (DR)

Predicting position by advancing from a known position based on courses and distances.

Piloting

Navigating in restricted waters with frequent position determination.

RADAR Navigation

Using RADAR to determine distance or bearing to known objects.

Satellite Navigation

Determining position using radio signals from satellites.

Celestial Navigation

Reducing celestial measurements to lines of position for navigation.

Geodesy

Applying mathematics to model Earth's size and shape.

Datum

Reference used for calculations or measurements.

Hydrography

Science of measuring features affecting marine navigation.

Cartography

Transforming hydrographic data into usable charts.

Lead Line

Device with a marked line and lead weight for depth measurement.

Wire Drag

Detecting submerged features in nearshore areas.

Echosounders

Determine depth by measuring sound pulse travel time.

Bathymetric LIDAR

Uses laser transmitters for hydrographic surveys.

Mercator Projections

Common projection for maritime navigation.

Gnomonic Projections

Reference lines projected from Earth's center onto a tangent plane.

Compass Rose

Measures direction using true or magnetic bearings.

Distance Scale

Measures distances on a chart.

National Ocean Service (NOS)

Charts coastal waters of the US.

Army Corps Of Engineers

Charts Mississippi River and inland lakes.

United Kingdom Hydrographic Office (UKHO)

Provides nautical charts for MOD and maritime organizations.

Chart No

Lists symbols found on nautical charts.

List of Lights (NGA)

Summary of navigation aids in international waters.

U.S

Detailed information about U.S. harbors and coastal areas.

Light List (USCG)

Summary of navigation aids in U.S. waters.

Fleet Guide (NGA)

Information for naval ships entering ports.

Nautical Almanac

Publication for celestial observations.

Distances Between Ports (NGA)

Calculates distances between ports worldwide.