CHARTS & NAVIGATION

LATITUDELATITUDE LATITUDESLATITUDES LONGITUDESLONGITUDES LINES PARALLEL TO EQUATOR LINES PARALLEL TO EQUATOR CONCENTRIC CIRCLES OF DIFFERENT SIZES CONCENTRIC CIRCLES OF DIFFERENT SIZES PARALLELS (Lines) – INCREASE NORTH & SOUTH OF EQUATOR (0°) FROM ZERO TO 90° PARALLELS (Lines) – INCREASE NORTH & SOUTH OF EQUATOR (0°) FROM ZERO TO 90° CAN BE DETERMINED BY USING A SEXTANT CAN BE DETERMINED BY USING A SEXTANT LINES PARALLEL TO EQUATOR LINES PARALLEL TO EQUATOR CONCENTRIC CIRCLES OF DIFFERENT SIZES CONCENTRIC CIRCLES OF DIFFERENT SIZES PARALLELS (Lines) – INCREASE NORTH & SOUTH OF EQUATOR (0°) FROM ZERO TO 90° PARALLELS (Lines) – INCREASE NORTH & SOUTH OF EQUATOR (0°) FROM ZERO TO 90° CAN BE DETERMINED BY USING A SEXTANT CAN BE DETERMINED BY USING A SEXTANT LINES RUN FROM POLE TO POLE LINES RUN FROM POLE TO POLE ALL SAME LENGTH ALL SAME LENGTH MERIDIANS (LINES) – INCREASE WEST & EAST OF PRIME MERIDIAN (0°) FROM ZERO TO 180° MERIDIANS (LINES) – INCREASE WEST & EAST OF PRIME MERIDIAN (0°) FROM ZERO TO 180° CAN BE DETERMINED with a CHRONOMETER (CALIBRATED TO GREENWICH MEAN TIME) CAN BE DETERMINED with a CHRONOMETER (CALIBRATED TO GREENWICH MEAN TIME) LINES RUN FROM POLE TO POLE LINES RUN FROM POLE TO POLE ALL SAME LENGTH ALL SAME LENGTH MERIDIANS (LINES) – INCREASE WEST & EAST OF PRIME MERIDIAN (0°) FROM ZERO TO 180° MERIDIANS (LINES) – INCREASE WEST & EAST OF PRIME MERIDIAN (0°) FROM ZERO TO 180° CAN BE DETERMINED with a CHRONOMETER (CALIBRATED TO GREENWICH MEAN TIME) CAN BE DETERMINED with a CHRONOMETER (CALIBRATED TO GREENWICH MEAN TIME) LONGITUDE

EQUATOR Imaginary line dividing our planet into northern & southern hemispheres p Equator0°

THE EARTH’S GRID

PRIME MERIDIAN: ESTABLISHED 1884 AT GREENWICH, ENGLAND 15° Longitude = One hour of Earth’s Rotation PRIME MERIDIAN STAND WITH ONE FOOT IN WESTERN & ONE IN EASTERN HEMISPHERE

GREENWICH, ENGLAND GPS shows the longitude to be W 000° 00’ 00.0” Indicating the Prime Meridian

THE INTERNATIONAL DATE LINE (IDL) OPPOSITE THE PRIME MERIDIAN, AT 180°OPPOSITE THE PRIME MERIDIAN, AT 180° NOT A STRAIGHT LINENOT A STRAIGHT LINE ALTERED TO BE CONSISTENT WITH LOCAL ISLAND GEOGRAPHYALTERED TO BE CONSISTENT WITH LOCAL ISLAND GEOGRAPHY Prime Meridian

THE NORTH POLE Earth's magnetic field (metallic core with magnetite): 2 magnetic poles (MP): Earth's magnetic field (metallic core with magnetite): 2 magnetic poles (MP): 1.) North MP (in Canadian arctic) 2.) South MP (off Antarctica’s coast, south of Australia) North MP is slowly drifting across Canadian ArcticNorth MP is slowly drifting across Canadian Arctic Canadian Geological Survey tracks motion with magnetic surveys to determine pole's locationCanadian Geological Survey tracks motion with magnetic surveys to determine pole's location Earth's magnetic field (metallic core with magnetite): 2 magnetic poles (MP): Earth's magnetic field (metallic core with magnetite): 2 magnetic poles (MP): 1.) North MP (in Canadian arctic) 2.) South MP (off Antarctica’s coast, south of Australia) North MP is slowly drifting across Canadian ArcticNorth MP is slowly drifting across Canadian Arctic Canadian Geological Survey tracks motion with magnetic surveys to determine pole's locationCanadian Geological Survey tracks motion with magnetic surveys to determine pole's location May 2001’s survey:May 2001’s survey: Pole moving NW ~24 miles/yearPole moving NW ~24 miles/year Nautical charts must be updated so compasses may be used Nautical charts must be updated so compasses may be used Magnetic north pole movesMagnetic north pole moves GPS is replacing compass GPS is replacing compass More accurate navigational toolMore accurate navigational tool

NORTH POLE SOUTH POLE PATH OF THE MAGNETIC NORTH POLE FROM 1600 TO 2000 – MOVES ABOUT 24 MILES A YEAR

THE CHART SCALE: relationship between the distance of 2 points represented on a chart & the same 2 points in the real world Usually referred to by a ratio: EX: 1:40,000  1 inch (on chart) = 40,000 inches (real world) SCALE: relationship between the distance of 2 points represented on a chart & the same 2 points in the real world Usually referred to by a ratio: EX: 1:40,000  1 inch (on chart) = 40,000 inches (real world) SYMBOLS: Indicate buoys, lights, foghorns, markers, whistles, etc. COMPASS ROSE - Circle within a circle used to indicate direction:  Both have degrees on them from 0° to 360°  Outer circle points to “true” north (gives true bearing)  Inner circle points to magnetic north (gives magnetic bearing) COMPASS ROSE - Circle within a circle used to indicate direction:  Both have degrees on them from 0° to 360°  Outer circle points to “true” north (gives true bearing)  Inner circle points to magnetic north (gives magnetic bearing) LATITUDE & LONGITUDE - Marked along edges of nautical charts, indicating degrees, minutes, & seconds

Reading charts Contour lines Depth Ft., Meters,Fathoms Symbols R9QTHK

Nautical chart Latitude & Longitude are marked along chart edges Always find these on chart: 1. Scale 1. Scale 2. Depth (Ft., Fathom, Meters) 2. Depth (Ft., Fathom, Meters) 3. Contour Lines 3. Contour Lines 4. Compass Rose 4. Compass Rose 5. Symbols 5. Symbols 6. Latitude & Longitude 6. Latitude & Longitude

THE COMPASS ROSE A circle within a circle used to indicate direction A circle within a circle used to indicate direction Both have degrees from 0° to 360°Both have degrees from 0° to 360° Outer circle points to geographic or true north (north pole) & gives true bearingOuter circle points to geographic or true north (north pole) & gives true bearing Inner circle points to magnetic north (in Canada) & gives a magnetic bearingInner circle points to magnetic north (in Canada) & gives a magnetic bearing Also shows the variation & annual increaseAlso shows the variation & annual increase Indicates True North Indicates Magnetic North Variation Annual increase

DEGREES, MINUTES, & SECONDS 1 MINUTE 1 DEGREE 12 SEC0NDS YOU WILL DETERMINE DEGREES, MINUTES, & SECONDS ON THE CHART (CAN VARY ON DIFFERENT CHARTS) YOU WILL DETERMINE DEGREES, MINUTES, & SECONDS ON THE CHART (CAN VARY ON DIFFERENT CHARTS) LONGITUDES ARE READ THE SAME WAY AS THESE LATITUDE READINGS 60 seconds in a minute

PLOTTING INSTRUMENTS

USING THE PARALLEL RULERS Parallel rulers allow you to follow a line accurately Connect 2 points Use with Compass Rose

DIVIDERS Dividers can be used to determine nautical miles (nautical mile scale on chart)

CHART PROJECTIONS (Show a representation of the globe) MERCATOR PROJECTION Most commonly used projection on nautical chartsMost commonly used projection on nautical charts Benefits:Benefits: Lines of longitude & latitude intersect at right angles, so directions can be plotted accuratelyLines of longitude & latitude intersect at right angles, so directions can be plotted accurately Shape of an object is accurately representedShape of an object is accurately represented Disadvantage: As you go towards the poles, objects appear larger than they actually areDisadvantage: As you go towards the poles, objects appear larger than they actually are Other projections (Gnomonic, Orthographic, Robinson)Other projections (Gnomonic, Orthographic, Robinson)

SOME USEFUL NUMBERS Statute mile = 5,280 feet, Nautical mile = 6, feet Statute mile = 5,280 feet, Nautical mile = 6, feet Statute miles x 0.87 = nautical miles Statute miles x 0.87 = nautical miles Nautical miles x 1.15 = statute miles Nautical miles x 1.15 = statute miles 1. Nautical miles - ocean & coastal waters 1. Nautical miles - ocean & coastal waters 2. Statute miles - inland areas (river, lake) 2. Statute miles - inland areas (river, lake) A Nautical Mile = 1/60th of a degree or 1 minute of latitude A Nautical Mile = 1/60th of a degree or 1 minute of latitude Use this phrase:"A minute's a mile the world around.”Use this phrase:"A minute's a mile the world around.” One degree of latitude = 60 nautical miles (All of Earth) One degree of latitude = 60 nautical miles (All of Earth) Each degree is divided up into 60 minutes Each degree is divided up into 60 minutes Each minute is further carved into either 60 seconds or decimal minutes Each minute is further carved into either 60 seconds or decimal minutes Coordinates of OCC Marine Science Department: Latitude: 33° 38’ 22” North Longitude: 117° 25’ 15” West Latitude: 33° 38’ 22” North Longitude: 117° 25’ 15” West 1 fathom = 6 feet = meters1 fathom = 6 feet = meters Nautical charts are updated every 2 years, on avg (6 mos. – 12 yrs.)

NAVIGATION: NECESSARY FOR OVERSEAS TRADE

Off we go into the sunset, hopefully knowing where we are going

Sextant Measures the angle between the horizon & the sun when the sun is at its highest point (noon) Tables show which line of latitude the sun should be above on that day Ex: Noon on 21 December (Sun directly overhead) On 21 Dec. sun is above Tropic of Capricorn Latitude = 23.5 ° S. The arm is positioned so the sun reflects off mirror B & off mirror A (& eyepiece) What you see: sun superimposed on horizon Angle between sun & horizon is read off the scale, compared with tables The sextant uses 2 mirrors: (1) Mirror A – horizon (2) Mirror B – sunlight reflects off (attached to a movable arm)

GREENWICH, ENGLAND HOME OF THE PRIME MERIDIAN & GREENWICH MEAN TIME Royal Observatory in Greenwich EnglandRoyal Observatory in Greenwich England Founded (1675) by King Charles IIFounded (1675) by King Charles II Built to solve Longitude Problem (finding east-west position) at sea & out of sight of landBuilt to solve Longitude Problem (finding east-west position) at sea & out of sight of land Greenwich Time Ball (1833):Greenwich Time Ball (1833): 1 of world's 1 st visual time signals1 of world's 1 st visual time signals Ball drops daily at 1300: used to check marine chronometersBall drops daily at 1300: used to check marine chronometers Can be seen from the Thames: sailors know exact timeCan be seen from the Thames: sailors know exact time RO is now a center for astronomyRO is now a center for astronomy