ORD-10 OrdinaryPiloting Instructors: George Crowl

Course Outline  a. Latitude / longitude. Plot positions.  b. Degree system of direction, variation, deviation  c. Measuring speed and distance  d. 24 hour time system  e. UTC / GMT / Zulu time and conversion  f. DR table of headings / distances  g. Use your Sea Scout Pocket Reference!

ORD-10a.  Demonstrate your understanding of latitude and longitude.  Using a Mercator chart, demonstrate that you can locate your position from given coordinates and determine the coordinates of at least five aids to navigation.

Latitude / Longitude  Latitude – Measured from equator, north or south  Maximum 90° N or S  Longitude – Measured from Greenwich, England, east or west  Maximum 180° E or W  (SSPR p. 22)

Latitude / Longitude Houston is about 30° north of the equator, and 90° west of Greenwich. Numbers increase up and left in the US.

60 Minutes per Degree  60 minutes per degree  1 minute = 1 nautical mile (measured north / south) (measured north / south)  1 NM = 6080 ft  60 seconds = 1 minute  1 second = 101 feet  In Java, latitude increases south and longitude increases east. Why?

Plotting a Position  Determine the parallels on the chart that bracket the latitude.  Place the pivot point of the compass on the closest line.  Spread the compass until the lead rests on the given latitude.  Move to the approximate longitude and swing an arc.

Plotting a Position  The same process is repeated using the longitude scale and the given longitude.  The desired position is the intersection of these two arcs.  If plotted correctly, the intersection should occur at the crest of both arcs.

Minutes / Seconds Minutes / Tenths, Hundredths  Measure in degrees, minutes, seconds (N29° 34’ 47”) OR Measure in degrees, minutes, and tenths, hundredths, thousandths (N29° ’) Measure in degrees, minutes, and tenths, hundredths, thousandths (N29° ’)  N 29° 34’ 47” = N 29° ’  See the left and bottom edges of your chart, and the 1/10’ marks on the middle.  EXERCISE – Plot the following coordinates:  N41°41.4' W072°05.5'  N41°40.2' W072°01.1'  N W  N W  N W

Plotted Points

Determine Coordinates of…  1. Channel Island Light Fl 8s 20ft 5M  2. Bowditch Bay Light G9 Fl G 4s  3. Oyster River Light G1 Fl G 2s  4. Bowditch Bay Buoy R N 14  5. Bowditch Bay Light R16 Fl R 4s

Coordinates are:  1. Channel Is Light N41°41.7' W071°53.7'  2. BB G9 Fl G 4s N W  3. OR G1 Fl G 2s N W  4. BB R14 R N 14 N W  5. BB R16 Fl R 4s N W

ORD-10b.  Explain the degree system of compass direction.  Explain variation and deviation, and how they are used to convert between true and compass headings and bearings.

Degree System of Compass Direction (Outer Ring)  360° in a circle, 0° and 360° at North (star)  090° = East  180° = South  270° = West  Any intermediate direction measured by numbered angle

North Magnetic Pole  Compass does not point N  Changes everywhere  Points 3° E here, so (-) subtract from True

Variation (inner circle)  Compass variation – same for all compasses  Plotted on chart compass rose  Listed on bottom of chart also  Look at your chart

Deviation Deflection of a compass needle caused by a magnetic influence

Deviation  Different on EVERY boat  Different on EVERY heading for every boat!  Also –E & +W Defiant Compass Swing 4 NOV 06 Motor on, under way TRUEVARMAGDEVCOMP

Variation, Deviation & Compass Correction  TC VAR MC DEV COMP  E W 116  T V Makes Dull Company -  Add Whisky (+W)  Hand compasses = no deviation, because deviation depends on where you are on the boat

Sample Deck Log

Compass Correction East is Least (-) “-3E” West is Best (+) “+15W”

Compass Correction  T True  V Variation  M Magnetic  D Deviation  C Compass  TV Makes Dull Company

Relative Bearings  The bearing of an object with respect to the fore & aft line of the ship  Is given in degrees  (Each clock bearing is 30°)

Relative Bearings (degrees)  000° is the bow of the ship  Clock positions are 030°, 060°, 090°, 120°…

ORD-10c.  Describe three kinds of devices used aboard ship for measuring speed and/or distance traveled and, if possible, demonstrate their use.

Speed Logs  Speed by RPM  Dutchman’s log 5”/30’ = 3.56KT  Ground Log  Chip Log  Patent Log  Taffrail Log  GPS

Chip Log

Patent / Taffrail Log

10c. Measure Speed and Distance  Distance is measured in  Nautical miles  = 6080 feet  Speed is measured in  Knots  (Nautical miles per hour)

Measuring Distance  Always measure distance on the Latitude scale!  OR – use the scale on the chart

Why We Use Vertical Scale

Measuring Course – Parallel Rules B SSPR p. 22 A Using parallel rules

Measuring Course – Plotter  Plotter – align using your dividers  Grommet on longitude line

Start your deck log with true course and distance. Start your deck log with true course and distance. Derive mag course and perhaps compass. Derive mag course and perhaps compass. Deck Log Plan

Speed Time Distance S (speed) D (distance) T (time) = 60 (minutes)

Estimate Speed, Calculate Time 6.0 = x9.3 = 558÷6.0 = 93 = X

ORD-10e.  Explain the 24-hour time system and demonstrate that you can convert between 12- and 24- hour time.

12- vs. 24-Hour Time 12-Hour 24-Hour 12-Hour 24-Hour 12-Hour 24-Hour 12-Hour 24-Hour  1:00 AM :00 PM 1300  2:00 AM :00 PM 1400  3:00 AM :00 PM 1500  4:00 AM :00 PM 1600  5:00 AM :00 PM 1700  6:00 AM :00 PM 1800  7:00 AM :00 PM 1900  8:00 AM :00 PM 2000  9:00 AM :00 PM 2100  10:00 AM :00 PM 2200  11:00 AM :00 PM 2300  Noon 1200 Midnight 2400

24-Hour Clock Faces

ORD-10d.  Understand Universal Coordinated Time (Greenwich Mean Time or Zulu Time) and zone time.  Demonstrate your ability to convert from one to the other for your local area.

Zone Time

UCT / GMT / Zulu  Zone Standard DST Zulu  Eastern  Central  Mountain  Pacific

ORD-10f.  Make a dead reckoning table of compass and distances (minimum three legs) between two points, plot these on a chart, and determine the final position.  Note : Ideally this requirement should be met while under way. If this is not possible, it may be simulated using charts.

Dead Reckoning  Record of ships progress based on  Course  Speed  Time traveled  Known starting point (fix)  Checked every hour, minimum  Checked at every course or speed change

Dead Reckoning Terms  DR Dead Reckoning Position  EP Estimated Position  Fix Established position by any means  LOP Line of Position  C Course  S Speed

Dead Reckoning (DR)  Start from a fix  Label all lines on chart  Numbers are rounded off  Use Military time  Courses & bearings are 3 digits (045, 218)  Label course with C & bearing with B (C045, B126) Speed in Knots (1/10 K) placed under the course line Distance to nearest 1/10 NM place after speed DR is marked by a dot and semicircle  Fix is marked by a dot and circle with the time  [·] and time Estimated position marked by a dot and square [·] and time

Chart Labeling C083 S8.4 D FIXDR Estimated Position

DR Exercise  Navigator cruising in Bowditch Bay.  Plan the cruise with given data.  We will then give you the instrument readings to make that cruise.

Deck Log RW OR to DR

Bowditch Bay RW OR to DR

DR to BB R6

BB R6 to RG D

RG D to RG CP

BB R6 to RG D

Exercise!  Handout  Compass  GPS Packet (GPS, Quick Start, Instructions)  We do ded reckoning on land, with a compass and timing our walks

Summary  Make a plan  Write it down (deck log, chart)  Follow it if you can  Navigation requires times. Write them down!  DR ahead, it makes life easier  The perfect is the enemy of the good. A decent new heading on time is better than a perfect one late.

Fair Winds  And a following sea