Section D-5 Plotting and Labeling

1. Section D-5 Plotting and Labeling 1

2. Objectives The student will: • Learn how to use the CPS plotter • Know how to label course lines, LOPs, DR positions, Fixes • Know the required standards of accuracy for chartwork • Be able to plan a cruise 2

3. The New Mk II Plotter • Used to measure TRUE directions on a chart 3

4. The New Mk II Plotter North Arrow ALWAYS points North (using Lat/Lo lines) Arrow indicates direction of Bearing Clear tape allows navigator to mark and measure distances Boat symbol indicates direction of travel Grid Lines Arrow points to Reciprocal reading on Plotter Rose Plotting Shapes 4

5. Points True North Parallel to Longitude Line Reading the Scales Variation 10° West 100° Magnetic 90° TRUE Longitude Chart Line 5

6. Reading the Compass Rose 000° 270° 090° 180° 6

7. Finding the TRUE & Magnetic course between two points N O R T H Variation 20° West 300° True 320° Magnetic C 300 / 320 M S 10.0 B A 7

8. We want to go 040° True from the aid Turn the Plotter Rose to the direction 040° Variation 20° East 020° Magnetic / 020 M S 10.0 C 040 Aid 8

9. True Bearing of 130° N O R T H Bearings go UNDER the line 130 / 110 M Aid Variation 20° East 110° Magnetic Turn the Plotter Rose to the bearing 130° 9

10. . Drawing Parallel Lines Required distance Original Line N O R T H Bearing of 340° should be maintained on plotter New Line Parallel Lines Plotter Rose indicates a bearing of 340° 10

11. Standards of Accuracy • For directions • to the nearest degree • in 3 digits (e.g. 075) • For time • to the nearest minute • in 4 digits (e.g. 1345) 11

12. Standards of Accuracy continued • For distances • to the nearest tenth of a nautical mile • 10.1 nm • For positions expressed as latitude and longitude • to the nearest tenth of a minute L 43° 21.3’ N Lo 123° 10.5’ W • For speed • to the nearest tenth of a knot • 5.2 kn 12

13. Planning a Cruise • Establish a point of departure • determine an accurate fix • aid “close aboard” means boat is at the aid • use dot (or circle) at base of charted aid • charted dock can be point of departure • Establish a destination • a clearly identifiable location marked on the chart and recognizable from boat • last part of any cruise is done through conning • Plot on chart 13

14. Plotting and Labelling Chart • Look for marked hazards • plot around them • Track is the line showing the intended path of the boat. • TRUE Course equals the Track unless compensating for wind or current • no wind or current in this course 14

15. Labelling Charts • A FIX • A DR position • Course Line • course in TRUE & Magnetic • speed • LOPs 15

16. The FIX Always draw lines from FIXes C 045 / 055 M S 6.0 Known position = FIX X A FIX is plotted as a dot inside a small circle 16

17. The DR Position • Plotted • at any convenient time interval • every hour on the hour • when change in course • when change in speed • when a bearing is taken • Usually plotted only one hour ahead of the boat’s position 17

18. The DR Position 0900 0800 C 045 / 055 M Note how all symbols have a dot marking the EXACT position S 6.0 FIX 0700 18

19. LOPs • Drawn TOWARD the object from seaward • Time is placed on the ‘north’ side of the line (FIX does not require LOPs labeled with time). • Direction of Bearing (in True) is placed on the ‘south’ side of the line followed by a slash and the Magnetic Bearing 19

20. Finding the Expected Duration • Measure along the course line from the point of departure to the destination • For Speed • powerboats, assume most economical cruising speed • sailboats, estimate from direction and force of wind • 60D=St , solve for t 20

21. T V M D C Finding the Compass Course to Steer To steer From compass rose From Course Plot T plus or minus V 0 in this course 21

22. Selecting Aids and Landmarks • Study chart to find aids and landmarks you can use for either conning or plotting • Identify possible LOPs • ranges, lights, steep cliffs, points of land in line, towers, steeples, depths 22

23. Using LOPs • LOPs drawn parallel with the track can give an indication of “cross-track error” • the boat’s distance to the left or right of the track • On the water, a back bearing on the point of departure will give an early indication if the boat is on track • calculate reciprocal, (boat track = +/- 180) • if back bearing equals reciprocal, boat on course • if back bearing less than reciprocal, boat is off course to left (Left Less) • if back bearing greater than reciprocal, boat is off course to right 23

24. Using LOPs continued • An LOP that cuts the track can give an estimate of the distance travelled from the last known position (FIX) • By taking time into account, determine • ETA • Speed Made Good 24

25. Using the measured distance (D), And the time (t) it took to get to that bearing you would find the Speed Made Good (SMG) with 60D=St Using your speed (s) and measured distance (D), you would find the time (t) expected to get to that bearing from the FIX with 60D=st Add the time to the FIX time to get ETA C 039 / 019 M S 10.0 1000 Measured distance 0947 25

26. At 1852, you alter course to 023°, again heading for buoy CS 47. You mark DRs for every whole hour. You realize the buoy straight ahead is CS 48 which marks an area of foul ground. At 1843, you spot a buoy ahead and think you are on track. You are the navigator on a boat coming into port at dusk on a wet and very windy night. You draw a line from your last FIX on a course of 054°T to the buoy CS 47. FIX You take a bearing of 347° True on a TV tower You plot DRs as every whole hour approaches. At 2034, you pass close aboard CS 47 and change course to 119° to follow the range into the harbour. You take a bearing of 091° True on a chimney. 2034 2100 1843 C 119 / 099 M S 6.0 2000 1800 C 023 / 003 M S 6.0 347 / 327 M C 054 / 034 M S 6.0 1700 1900 1852 091 / 071 M 1843 26

27. Keeping a LOG • To maintain a permanent record of the cruise • Enter • times • courses steered • bearings • FIXes • ETAs • Latitude & Longitude 27

28. L O G 28