1. Section D-5 Plotting and Labeling1

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. Emphasize used to measure TRUE directions
The New Mk II Plotter
Used to measure TRUE directions on a chart
Emphasize used to measure TRUE directions
the wheel turns 3

4. The New Mk II Plotter
Clear tape allows navigator to mark and measure distances
North Arrow ALWAYS points North (using Lat/Lo lines)
Arrow indicates direction of Bearing
Boat symbol indicates direction of travel
Grid Lines
Arrow points to Reciprocal reading on Plotter Rose
Build slide – goes through all of the features one by one.
Dwell on the North Arrow and lat/lo lines
Plotting shapes:
Fix, DR, GPS, Bearing
Boat and bearing direction
Explain reciprocal
Additional grid lines
Plotting Shapes 4

5. Points True North Parallel to Longitude Line
Reading the Scales
Points True North Parallel to Longitude Line
Variation
10° West
100°
Magnetic
Lo chart line
Point to TRUE north
Variation scale
Multiple build
90° TRUE
Longitude Chart Line 5

6. Reading the Compass Rose
000°
270°
Reading the Compass Rose
090°
Multiple build
may need to repeat once or twice
180° 6

7. Finding the TRUE & Magnetic course between two points
Variation
20° West
300° True
320°
Magnetic
C 300
/ 320 M
Place plotter in direction of travel (we are going from A to B
Draw course line
Align Lo line with chart Lo line
Read off TRUE direction 300 deg
Note VAR 20 deg W
Label C300 / 320M and speed
Mention the exercise on Page D43 – do on own time at home
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
We know the FIX position (close aboard charted aid “AID”)
Want to travel 040 True from AID
Set 040 on plotter
Align plotter rose with any Lat line
Align plotter edge with AID
Draw course line
Calculate VAR
Label
Aid 8

9. Bearings go UNDER the line
True Bearing of 130° N O R T H
Bearings go UNDER the line
130
/ 110 M
We need to travel towards a mark at a bearing of 130 TRUE
Point plotter towards aid
Set 130 on the plotter rose
Align plotter rose line with nearest Lo line and edge of plotter with Aid
Draw course line
Set VAR
Label bearing UNDER the line
Aid
110° Magnetic
Variation
20° East
Turn the Plotter Rose
to the bearing 130° 9

10. . Drawing Parallel Lines
Required distance
Original Line N O R T H
New Line
Bearing of 340° should be maintained on plotter
Parallel Lines
Method of finding parallel line
Assume we have an existing course line
Align plotter edge with the course line
Align plotter rose with Lo line with rose point North
Read off True direction (340)
Set required distance off (how?)
Slide plotter to new position while maintaining 340 set
Draw new course line
Plotter Rose
indicates a bearing of 340° 10

11. Standards of Accuracy For directions For time to the nearest degree
in 3 digits (e.g. 075)
For time
to the nearest minute
in 4 digits (e.g. 1345)
Directions
Nearest degree (round up)
For time
To nearest minute
In 4 digits 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
Distances
Nearest 10th of a nm (10.1 nm)
Lat/Long
Nearest 10th of a minute
Speed
Nearest 10th 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
We assume two crew – one to handle navigation full time 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 LOPs
course in TRUE & Magnetic
speed
LOPs 15

16. A FIX is plotted as a dot inside a small circle
The FIX
Always draw lines from FIXes
C 045 / 055 M
S 6.0
Known position = FIX X
FIX – a known and charted position
Dot in a circle
We draw lines from the FIX
Label appropriately
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 We start from a FIX – label it Label course line
0900
0800
C 045 / 055 M
Note how all symbols have a dot marking the EXACT position
S 6.0
FIX
We start from a FIX – label it
Label course line
Label the DR at convenient interval – we are using 60 minutes
The DOT marks the EXACT position (calculated!)
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. Finding the Compass Course to SteerV T
From
Course Plot
From
compass rose
T plus or minus V
in this course
To steer
Start with “T” and ask class where we find each piece of information
Slides builds with answers 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. Starting from FIX, calculate first DR and label Label course
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
Using DR and bearings
Starting from FIX, calculate first DR and label
Label course
Plan ahead to establish when abeam Pt Cowan light (what’s that?)
Measure Distance (how?) and use what (60Dst) to calculate time to reach that position (ETA) – why ETA?
When actually at bearing you can get the SMG
1000
Measured distance
0947 25

26. Work way through the build
At 2034, you pass close aboard CS 47 and change course to 119° to follow the range into the harbour.
You mark DRs for every whole hour.
You take a bearing of 347° True on a TV tower
At 1843, you spot a buoy ahead and think you are on track.
You realize the buoy straight ahead is CS 48 which marks an area of foul ground.
FIX
At 1852, you alter course to 023°, again heading for buoy CS 47.
You take a bearing of 091° True on a chimney.
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.
You plot DRs as every whole hour approaches.
2034
2100
1843
C 119 / 099 M
S 6.0
2000
1800
Refer to Fig D-5.7 in notes
Work way through the build
C 023 / 003 M
S 6.0
347 / 327 M
C 054 / 034 M
1700
S 6.0
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
Log pages at back of notes
This is the last slide 28