1. Plotting Celestial LOPs
Junior Navigation
Chapters 8 & 9
and part of Chapter 13
THE OUTER SCALE IS READ FROM A
MERIDIAN OF LONGITUDE. THE
INNER SCALE FROM A PARALLEL
OF LATITUDE.
090
270
180
000
080
070
060
050
040
030
020
010
260
250
240
230
220
210
209
190
100
110
120
130
140
150
160
170
280
290
300
310
320
330
340
350
360
200

2. Learning Objectives
Set up a Constant Latitude Scale Small Area Plotting Sheet (CLS SAPS)
Plot a single celestial LOP
Plot a celestial running fix
Meridian Transit of the sun
Setup a Universal Plotting Sheet (UPS) – Chap 13

3. Plotting Techniques
Errors result - working too fast - not checking plots
Don’t rush
Sharp-pointed pencil (medium/hard)
Complete plot before labeling
Erase unnecessary lines
Recheck results if they differ by more than 0.5´ on CLS Sheets. Small variations are normal

4. Constant Latitude Scale Small Area Plotting Sheet
Directions from Compass Rose
Latitude Scale fixed, you select Mid-Lat
You create the Lo scale for your area using arcs on lower part of form 1’ 3’ 5’ 7’ 9’ 2’ 4’ 6’ 8’ 1º

5. Constant Latitude Scale Small Area Plotting Sheet
30’
Plot 1258 DR at:
L 44º 50.6’ N
Lo 92º 21.2’ W
30’
20’
10’
STEP 1
Label ‘Mid Lat’ that will allow plot to be near center of form.
Label each of the 10’ increments.
45ºN
50’
40’
30’

6. Constant Latitude Scale Small Area Plotting Sheet
30’
Plot 1258 DR at:
L 44º 50.6’ N
Lo 92º 21.2’ W
45ºN
30’
20’
10’
50’
40’
45º
STEP 2
Lo varies to Mid-Lat
Draw diagonal lines between the bottom center & preprinted values for selected Mid-Lat

7. Constant Latitude Scale Small Area Plotting Sheet
30’
Plot 1258 DR at:
L 44º 50.6’ N
Lo 92º 21.2’ W
45ºN
30’
20’
10’
50’
40’
1º latitude
1º longitude
60nm x 60nm
THE OUTER SCALE IS READ FROM A
MERIDIAN OF LONGITUDE. THE
INNER SCALE FROM A PARALLEL
OF LATITUDE.
090
270
180
000
080
070
060
050
040
030
020
010
260
250
240
230
220
210
209
190
100
110
120
130
140
150
160
170
280
290
300
310
320
330
340
350
360
200
STEP 3
Intersections of diagonal lines and solid arcs mark locations of 10’ meridians
Draw meridians
Label meridians
You are on your way in becoming a cartographer
20’
10’
30’
40’
50’
92ºW
50’

8. Constant Latitude Scale Small Area Plotting Sheet
30’
Plot 1258 DR at:
L 44º 50.6’ N
Lo 92º 21.2’ W
45ºN
30’
20’
10’
50’
40’
92ºW
THE OUTER SCALE IS READ FROM A
MERIDIAN OF LONGITUDE. THE
INNER SCALE FROM A PARALLEL
OF LATITUDE.
090
270
180
000
080
070
060
050
040
030
020
010
260
250
240
230
220
210
209
190
100
110
120
130
140
150
160
170
280
290
300
310
320
330
340
350
360
200
THE OUTER SCALE IS READ FROM A
MERIDIAN OF LONGITUDE. THE
INNER SCALE FROM A PARALLEL
OF LATITUDE.
090
270
180
000
080
070
060
050
040
030
020
010
260
250
240
230
220
210
209
190
100
110
120
130
140
150
160
170
280
290
300
310
320
330
340
350
360
200
STEP 4
Plot your position
1258

9. Constant Latitude Scale Small Area Plotting Sheet
30’
Plot 1258 DR at:
L 44º 50.6’ N
Lo 92º 21.2’ W
45ºN
30’
20’
10’
50’
40’
92ºW
1258
THE OUTER SCALE IS READ FROM A
MERIDIAN OF LONGITUDE. THE
INNER SCALE FROM A PARALLEL
OF LATITUDE.
090
270
180
000
080
070
060
050
040
030
020
010
260
250
240
230
220
210
209
190
100
110
120
130
140
150
160
170
280
290
300
310
320
330
340
350
360
200
STEP 5
With sun intercept 4.0nm towards and azimuth 205º, plot your estimated position
1258 Sun
EP L 44º 47.0’ N Lo 092º 24.5’ W

10. Constant Latitude Scale Small Area Plotting Sheet
30’
Sight reduced from FIX:
Not an EP, do not draw a square
Sight Error (SErr) intersection of LOP and azimuth
45ºN
30’
20’
10’
50’
40’
92ºW
1258 GPS
1258 Sun
S Err 4.0nm
EP L 44º 47.0’ N Lo 092º 24.5’ W

11. Celestial Fixes
Celestial fix - sights on two/more different bodies taken within a short time
Time interval within 20 minutes - a “Fix”
Time interval longer - a “Running Fix”
Offshore navigators rely on Sun RFix
Morning LOP advanced to midday
Midday LOP advanced to evening
Evening LOP advanced to next morning .

12. Plotting a Celestial R Fix
Advancing a LOP using a construction line that parallels the DR track
45ºN
30’
20’
10’
50’
40’
0.9nm T 245º 0.8nm A 332º
0800
0900
C 260
S 6.0
1000
1100
0800
Sun
C 200
S 6.0
260
1200
200
1200 RFix
1200
Sun
Sun

13. Plotting a Celestial R Fix
Advancing a LOP using direction and distance between DR’s.
45ºN
30’
20’
10’
50’
40’
0.9nm T 245º 0.8nm A 332º
0800
0900
C 260
S 6.0
1000
1100
0800
Sun
C 200
S 6.0
THE OUTER SCALE IS READ FROM A
MERIDIAN OF LONGITUDE. THE
INNER SCALE FROM A PARALLEL
OF LATITUDE.
090
270
180
000
080
070
060
050
040
030
020
010
260
250
240
230
220
210
209
190
100
110
120
130
140
150
160
170
280
290
300
310
320
330
340
350
360
200
1200
1200 RFix
1200
Sun
Sun

14. Plotting a Celestial R Fix
Advancing a LOP using the original intercept and azimuth
45ºN
30’
20’
10’
50’
40’
0.9nm T 245º 0.8nm A 332º
0800
0900
C 260
S 6.0
1000
1100
0800
Sun
C 200
S 6.0
1200
1200 RFix
1200
Sun
Sun

15. Sight Folder Plotting S Err 3.6nm 45ºN 30’ 20’ 10’ 50’ 40’ 40’ 10’
0858
Sun
1245
Sun
1245 RFix
GPS
S Err 3.6nm
40’
10’
93ºW
50’
30’
20’
10’

16. Sight Folder Plotting Changing position where sights taken.
30’
20’
10’
50’
40’
Changing position where sights taken.
Sun
0858
Sun
1245
Sun
1245 RFix
1245
GPS
Resulting RFix must still be within 5.0nm of later sight.
0858
GPS
S Err 4.0nm
40’
10’
93ºW
50’
30’
20’
10’

17. Universal Plotting Sheets
Offshore: plotting & labeling of courses & bearings – referenced to TRUE
Universal plotting sheets used in any part of the ocean except Polar Regions
Likely to cross several lines of variation offshore.
Using True, apply Var & Dev for each leg to determine Compass course to steer.

18. Universal Plotting Sheets
The UPS covers about 4° of latitude and 4° of longitude
Draw meridian through marks on Compass Rose at desired mid-latitude 18 18

19. Universal Plotting Sheets
Setup for mid-latitude of 37° N and mid-longitude of 68° W 30 7
THE OUTER SCALE IS READ FROM A
MERIDIAN OF LONGITUDE. THE
INNER SCALE FROM A PARALLEL
OF LATITUDE.
090
270
180
000
080
070
060
050
040
030
020
010
260
250
240
230
220
210
209
190
100
110
120
130
140
150
160
170
280
290
300
310
320
330
340
350
360
200
Will be used for chapter 13 homework cruise 30 7 19 19

20. Universal Plotting Sheets
Setup for mid-latitude of 37° N and mid-longitude of 68° W
68ºW
69º
70º
66º
67º
37ºN
38º
39º
36º
35º
Set dividers to the spacing between central meridian and the one drawn
Measure off and draw remaining meridians
Label 20 20

21. Universal Plotting Sheets
68ºW
69º
70º
66º
67º
37ºN
38º
39º
36º
35º
Distance & latitude -measured along Latitude scale on central meridian
35º
36º
37º
38º
39º
Longitude - measured on pre-printed scale
draw line across at value of mid-lat 21 21

22. Longitude Measurements
Measure 15’ of Longitude at 37° Latitude.
Precision on UPS – 1.0nm or 1’ of Latitude/Longitude.
10’ 5’ + 22 22

23. YOU WILL USE THIS UPS FOR PLOTTING THE CHAPTER 13 HOMEWORK CRUISE
Universal Plotting Sheets
68ºW
69º
70º
66º
67º
37ºN
38º
39º
36º
35º
15º W Var
(ZD+5) (ZD+4)
Plot the 15º W isogonic line using points: L1 39º 00’ N, Lo1 69º 20’ W and L2 35º 00’ N, Lo2 66º 45’ W…
Time Zone Boundaries
Vertical dashed line, with ZD on both sides
YOU WILL USE THIS UPS FOR PLOTTING THE CHAPTER 13 HOMEWORK CRUISE
Isogonic Lines
Lines of equal magnetic variation
Dashed line, with variation shown
15º W Var 23 23

24. Universal Plotting Sheets
15º W Var
68ºW
30’
69º
67º
68ºW
69º
70º
66º
67º
15º W Var
37ºN
30’
38º
36º
37ºN
38º
39º
36º
35º
(ZD+5) (ZD+4)
(ZD+5) (ZD+4) 5 10 15 20 25
DOUBLING THE SCALE
15º W Var
15º W Var 24 24

25. Meridian Transit of Sun also known as Local Apparent Noon (LAN)
Celestial body crosses upper branch of observer’s meridian – body reaches maximum altitude
LHA is 000°
Body due north/south
Azimuth 360º or 180º
Nav. triangle collapses to straight line - elevated pole, observer, & GP of body - all on same great circle: the observer’s meridian
Meridian Transit of Sun also known as Local Apparent Noon (LAN)
Observer
GP Sun
Equator
Greenwich Pn 25 25

26. Finding Time of Transit
Mean time of transit is calculated 26 26

27. Finding Time of Transit
Find ZT of MT on 14 Nov at Lo 092° 21.2´W
Step 1
Record the DR Lo
Step 2
Find whole hour GHA from daily page of Nautical Almanac, closest to, but still smaller than DR Lo 14 27 27

28. Finding Time of Transit
Find ZT of MT on 14 Nov at Lo 092° 21.2´W
Step 3
Record GHA
Step 4
Subtract whole hour GHA from DR Lo
Step 5
Browse increments / corrections pages 18 28 28

29. Finding Time of Transit
Find ZT of MT on 14 Nov at Lo 092° 21.2´W
Step 6
Record increment
Step 7
Add to GHA whole hour
Step 5
Correct for ZD 18 6 +
ZD: 21.2’ / 60 =
º / 15 = 6.15 29 29

30. Computing Latitude The Ultimate Backup
Determine Lat w/o calculator, tables, or plotting
Simple and easy to teach to crew members
Quick check of GPS latitude
However, limited availability
Only once a day, at a specific time
Ann
Changed wording of a few bullets 30 30

31. Computing Latitude Correct WT and hs of the sight at maximum altitude
Subtract Ho from 90° to obtain Co-Alt
For UT of the sight, obtain Dec of sun from Almanac
Combine Co-Alt and Dec to obtain your latitude
L = Dec + Co-Alt 31 31

32. Computing Latitude Observer North of Sun 70 20 10 30 50°N Observer
CoAlt 70
Observer 20 10
Sun 30
Equator
50°S 32 32

33. Computing Latitude Observer South of Sun 30 60 20 40 50°N Sun Equator
CoAlt
Observer
50°S 33 33

34. Taking the Noon Sight
Begin taking sights 10 to 20 minutes before ZT of MT
Take observations every minute or two
Note altitude and time
Rate of altitude increase slows as sun approaches meridian transit
Near transit, altitude may appear nearly constant for a few minutes
Helpful to plot run of sights 34 34

35. What’s your azimuth angle?
Latitude from MT Sight
DR position on 20 April:
L 48° 54.0´ N
Lo 125° 26.0´ W
From a series of sights around noon, you selected the maximum observed altitude
hs of sun (LL) is 52° 28.9´ at –18–26.
WE 2s slow.
HE 10.2 feet, IC +1.2´ 20
20 29 8 +
What’s your azimuth angle?
20 Apr 2012 02 + 8
20 Apr 2
10 2
1 2
3 1
1 2
1 9 –
You
Co-Alt
Sun 20
15 2 +
10 0 35 35

36. Meridian Transit of the Sun
End of
Junior Navigation
Chapter 9
Bring your Pilot Chart next week and Begin Preparing Sight Folders 36 36