Boating Skills & Seamanship

1. Boating Skills & Seamanship Lesson 9 Introduction to Navigation Approved by DC-E USCG AuxA, Inc

2. Lesson Objectives • Select, Use, And Keep Current Charts • Identify Objects On A Chart • Use Piloting Tools • Compass Mounting • Determining Position (LOP) • Measuring Distance On Charts • Principles Of Dead Reckoning • Compute Time,Speed, And Distance

3. Navigator’s Tools • Charts • Magnetic Compass • Course Plotter – Parallel Rulers • Dividers • Good Pencils - Erasers • Binoculars - 7 x 50 • Means Of Finding Water Depth • Electronic Tools

4. Map vs Chart • Map • Symbolic picture of a position of the earth drawn to scale • Nautical Chart • Map that emphasizes features useful to the mariner • Shape of the coastline • Landmarks • Depths

5. Chart Projection • Converts Spherical Area (Earth) To A Flat Piece Of Paper (Chart) • Two Main Types Of Projections • Mercator • Conical

6. The Mercator Projection • Points On The Earth Projected Onto Cylinder • Portions Of Cylinder Become Flat Surface When Cut Apart • All Angles Correctly Represented So Course Lines Can Be Measured Accurately • Distortion Magnified As You Go North Or South, So Unusable Near Poles

7. A A Mercator Projection Lines of Longitude Projected Parallel The Further AwayFrom The Equator, The Greater The Distortion Spherical Surface Projected On A Cylinder

8. The Polyconic Projection • Earth’s Surface Projected On A Series Of Cones • Less Distortion At High Northern And Southern Latitudes • Measuring Can Only Be Done From The Center Of The Chart

9. Conical Projection Less Distortion in Northern/Southern Areas

10. Strip Charts • Segments Of Larger Traditional Charts • Printed On Small Panels & Enclosed In A Folder • Easier To Handle On Small Boat • Sections May Not Be Printed With North At The Top

11. General Information Block

12. Chart Scales • Large Scale = Small Area • Small Scale = Large Area • 1:80,000 Smaller Scale Than 1:40,000 • 1:80,000 Means 1 INCH On CHART Equals 80,000 Inches On Earth • Always Use Largest Scale Possible

13. Harbor 1:2,000 1:40,000 Coast 1:40,000 1:150,000 General 1:150,00 1:600,000 Sailing 1:600,000 1:14,000,000 Chart Scales (Cont)

14. Nautical Chart Catalog 1 Chart Information Chart Selection

15. Chart Datum • Datum • Benchmark term from which a chart’s vertical or horizontal measurements are made • Vertical Clearance • Based on Mean High Water • Depth • Based on Mean Lower Low Water (MLLW)

16. Vertical Clearance Actual Clearance MHW Mean Range Height of Tide MLW orMLLW WaterDepth Charted Depth Vertical Chart Datum Boat’s Actual Clearance

17. Positions On The Surface Of The Earth • System Of Coordinates • Great Circle - a plane that passes through the center of the earth • When it also passes through both Geographic poles it is a Meridian or Line of Longitude • The Equator is also a Great Circle • Small Circle – any plane passing through the earth but not the CENTER of the earth. • a small circle plane that is parallel to the equator is called a Parallel or Line of Latitude

18. Latitude and Longitude Parallels of Latitude Meridians of Longitude

19. Latitude

20. Measuring Latitude Line A-B Center of the earth to equator (radius) Line A – C Center of earth to parallel Angle = 60 º C A B

21. Longitude

22. Measuring Direction • Use Chart’s • Compass Rose (360° in any direction) • Meridians of Longitude (vertical coordinate) • Parallels of Latitude (horizontal coordinate) • Tools • Compass • Parallel Rulers • Course Plotter • Paraglide Plotter • Dividers

23. Top Reading Front Reading Inclinometer Direct Digital Telltale Compass Fluxgate The Compass

24. Compass Errors • Variation • Due to angular difference in direction to true north and magnetic north poles • Same for every boat in one area • Deviation • Due to magnetic influences aboard boat • Different for every boat • Changes with boat heading

25. Understanding Variation • Polar North vs. Magnetic North • Earth’s magnetic core does not coincide with geographical north • Every Chart Will Have 1 to 4 Compass Roses To Indicate Variation Of That Area • An annual increase in variation occurs due to plate tectonics • Increase may be 1’ to 9’ or more each year • Important to use most recent edition of charts

26. Relative Positions of Poles

27. Polar Variation Variation is the angular difference between the geographic and magnetic meridians Geographic North Pole Observer’s position Magnetic North Pole

28. Compass • Points to North Magnetic Pole • Area that changes slightly • Far northern Canada • True North • Earth’s axis • Base for latitude and longitude

29. The Compass Rose As Seen On The 1210-Tr ChartSouth of Rhode Island = True North = Magnetic North

30. Deviation • Any Magnetic Field Aboard A Vessel Strong Enough To Effect The Compass • Engines, electronic instruments, wires, steering wheel, especially the radio ‘s speaker • Deviation is specific to each individual vessel • Deviation will vary depending upon vessel’s heading • If more than one or two degrees, a DEVIATION TABLE should be constructed

31. Correcting Compass Errors T True Heading Tele- V Variation Vision M DOWN ADD WEST Makes Magnetic Heading D Dull Deviation C Children Compass Heading (Add Wonder)

32. True Heading Compass Rose

33. 015 Degrees West Variation

34. 005 Degrees West Deviation

35. 005 Degrees West Deviation

36. Compass Review • Variation • Local difference, East or West, between the direction of true and magnetic north • Deviation • Error caused by magnetic influences within the boat based on its heading

37. Measuring Distance • One Degree Of Latitude Equals 60Nautical Miles • One Minute Of Latitude Equals OneNautical Mile • Use • Latitude scale at vertical side of chart, or • Distance scale

38. Expressing Course Or Direction • True Heading • Can be affected by variation • Used to plot a course • Magnetic Heading • Difference from true caused by variation • Compass Heading • Deviation from magnetic heading caused by magnetic influences on boat • Used to steer a course

39. Finding Your Position • Line of position (LOP) • Range LOP • Bearing LOP • Loran time differential (TD) LOP • Circle of position (COP) • Distance from an object • RADAR • GPS

40. Positioning • To Fix Your Position • Where Two Lines Of Position (LOP) Cross • Where Two Circles Of Position (COP) cross • Where one LOP & one distance or COP cross • Third value to validate

41. Positioning • Obtaining an LOP • Use hand-held compass (bearing) • Turn vessel so bow is centered on object • Range: two objects that line up • LORAN reading • RADAR or GPS reading

42. 1400 FIX 1400 260 1400 200 Fixes Where Two LOPs Cross Tank Tower

43. Measuring Speed • Speedometers – Give Speed Over Water • On small boats, not especially accurate • More Accurate Speed Indication Based on Tachometer Readings (RPMs) • Still Speed over the Water • Need Speed Over the Bottom (Ground) • Takes into consideration the effects of current and wind • Essential when computing time, speed, and distance problems • Obtain from fixes or electronic (RADAR, GPS or LORAN)

44. Direction 2 Direction 1 Average RPM Time Speed Time Speed Speed 800 12 m 5 kts 15 m 4 kts 4.5 kts 1000 10 m 6 kts 12 m 5 kts 6.5 kts 1500 7 m 8.5 kts 8 m 7.5 kts 8 kts 2000 6 m 10 kts 7.5 m 8 kts 9 kts 3000 5 m 12 kts 6 m 10 kts 11 kts Speed Table Determining Speed

45. Vessel Run Over Measured Mile 12 10 8 SPEED (Kts) 6 4 2 0 0 800 1000 1500 2000 3000 Speed Curve RPM

46. Computing Distance Speed and Time • Some Examples: • Suppose you drive your boat at a speed of 20 Knots for 12 minutes. Howfarhave you gone? • Howlong does it take to travel 4 Nautical Miles at a speed of 20 Knots? • How fast are you going if you travel 4 Nautical Miles in 12 minutes?

47. 60 x D S T Speed – Distance - Time “Sixty D Street” 60D=ST S=60 T T=60 S D=ST 60

48. Computing Formulas • Time: T = 60 D /S • 60 X 4 Miles = 240 / 20 knots = 12 minutes • Distance: D = (S X T) / 60 • 20 Knots X 12 min = 240 / 60 = 4 Nautical Miles • Speed: S = 60 D / T • 60 X 4 Miles = 240 / 12 min = 20 Knots

49. Primary Methods Of Navigation • Dead Reckoning • Piloting • Celestial Navigation • Electronic Navigation • Inertial Guidance

50. Dead Reckoning • Deduced Reckoning • Process of determining a ship’s approximate position by applying to the last well determined position, a series of vectors, representing the run that has since been made • Only TRUE courses are used by the Navy and Coast Guard • Small boats can substitute magnetic