Session 3 Measuring Latitude and Longitude We are located West of the Prime meridian and North of the Equator. L A T I T U D E S C A L E 090 N Latitude is measured from zero One minute of latitude The latitude degrees at the equator to 90 scales are is equal to poles. one degrees at the found at the nautical mile. In our area, the latitude scale, 000 left and at the right or right left-hand margin, The latitude scales margins ofthe a bottom of increases from can becharts used to the our nautical toward chart. measuretop. distance. 090 S L A T I T U D E S C A L E LONGITUDE SCALE Longitude is measured from The Longitude zero at the prime meridian in Greenwich,Scales UK, eastare and west to a pointlocated in the Pacific Ocean. at the top and scale, In our area, the longitude at the topbottom or bottom ofmargin, a increases from right to left nautical chart.. LONGITUDE SCALE General Rules On a chart, LAT/LON is read in: Degrees Minutes Seconds Set your GPS to read out in this LAT/LON expression. LAT/LON Expressions On a Nautical Chart: 042 deg 56 min 45 sec North 072 deg 45 min 25 sec West Typical GPS or LORAN read out: 042 56.750 N 072 45.417 W Rules for reading LAT/LON On a Nautical Chart: Read the Degrees from the LAT/LON scales. Read the Minutes from the LAT/LON scales. Measure the Seconds. Finding Your Latitude Position Latitude Scale Longitude Scale SMALL SCALE CHART W Or ‘A’ Fl 4sec BELL Measuring the Seconds of Latitude. Step ONE – Place one point of the dividers on the object or target. Step TWO - Stretch the other point of the dividers to nearest Parallel of Latitude. Step THREE Without disturbing the opening, move the dividers to the Latitude scale in the left or right margins. 2 3 Step FOUR - Read the seconds of latitude. 4 1 The LATITUDE SCALE on a The LATITUDE Scale Small Scale Chart usually The parallel decimal minutes. depicts line from the Bell. 041 10.7” N 11.0 min. Seconds 041 10’ 42” N 10.5 min Degrees 10.0 min. Minutes DISTANCE One Minute of Latitude equals One Nautical Mile DISTANCE Sixty Seconds of Latitude equals One Nautical Mile The Second Scale on a Small Scale Chart 1/10 of a Mile ONE NAUTICAL MILE 6 seconds SIXTY SECONDS OF LATITUDE Finding your Longitude Position Latitude Scale Longitude Scale SMALL SCALE CHART W Or ‘A’ Fl 4sec BELL Measuring the Seconds of Longitude Step ONE - Place one divider point on the object or target.. Step TWO - Stretch the other point of the dividers back to the nearest meridian of Longitude. 2 Step THREE - Without disturbing the opening, move the dividers to the Longitude Scale at the top or bottom margin. 1 3 Step FOUR - Read the seconds of Longitude. 4 The Longitude Scale The vertical line from the Bell. Seconds Minutes 071 01.4’ W or 071 01’ 24” W Degrees Any questions about how to read and plot Latitude and Longitude?