1 plotting celestial lops junior navigation chapters 8 & 9 and part of chapter 13
TRANSCRIPT
11
Plotting Celestial LOPsPlotting Celestial LOPs
Junior NavigationJunior Navigation
Chapters 8 & 9 Chapters 8 & 9
and part of Chapter 13and 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 070060
050
040030
020010
000
260 250240
230
220210
209190
180
100110
120
130
140
150
160
170
180
280290
300
310
320
330
340
350
360
170 160150
140
130
350 340 330320
310
190200
210
220
230
010020
030
040
050
22
Learning ObjectivesLearning 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
Plotting Techniques
Don’t rush Sharp-pointed pencil (medium/hard) Complete plot before labeling Erase unnecessary lines
Errors result - working too fast - not checking plots
Recheck results if they differ by more than 0.5´ on CLS Sheets. Small variations are normal
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
Constant Latitude Scale Small Area Plotting Sheet
Plot 1258 DR at: L 44º 50.6’ N Lo 92º 21.2’ W
STEP 1 Label ‘Mid Lat’ that
will allow plot to be near center of form.
Label each of the 10’ increments.
30’
45ºN
30’
20’
10’
50’
40’
30’
Constant Latitude Scale Small Area Plotting Sheet
Plot 1258 DR at: L 44º 50.6’ N Lo 92º 21.2’ W
STEP 2 Lo varies to Mid-Lat Draw diagonal lines
between the bottom center & preprinted values for selected Mid-Lat
30’
45ºN
30’
20’
10’
50’
40’
30’
45º
Constant Latitude Scale Small Area Plotting Sheet
Plot 1258 DR at: L 44º 50.6’ N Lo 92º 21.2’ W
STEP 3 Intersections of
diagonal lines and solid arcs mark locations of 10’ meridians
Draw meridians Label meridians
30’
45ºN
30’
20’
10’
50’
40’
30’1º
lati
tude
1º longitude
60nm x 60nm
92ºW 50’
You are on your way in becoming a
cartographer
10’30’40’50’20’
TH
E O
UT
ER
SC
AL
E IS
RE
AD
FR
OM
A
ME
RID
IAN
OF
LO
NG
ITU
DE
. TH
E
INN
ER
SC
AL
E F
RO
M A
PA
RA
LL
EL
OF
LA
TIT
UD
E.
090
270
180
000
080
070
060
050
040030
020010 000
260
250
240
230
220210
209 190 180
100
110
120
130
140
150
160170 180
280
290
300
310
320
330
340350 360
170
160
150
140
130
350
340
330
320
310
190
200
210
220
230
010
020
030
040
050
45ºN
30’
20’
10’
50’
40’
30’
92ºW10’30’20’
40’50’ 50’
Constant Latitude Scale Small Area Plotting Sheet
Plot 1258 DR at: L 44º 50.6’ N Lo 92º 21.2’ W
STEP 4 Plot your position
30’
THE OUTER SCALE IS READ FROM A
MERIDIAN OF LONGITUDE. THE
INNER SCALE FROM A PARALLEL
OF LATITUDE.
090
270
180
000
080 070060
050
040030
020010
000
260 250240
230
220210
209190
180
100110
120
130
140
150
160
170
180
280290
300
310
320
330
340
350
360
170 160150
140
130
350 340 330320
310
190200
210
220
230
010020
030
040
050
TH
E O
UT
ER
SC
AL
E IS
RE
AD
FR
OM
A
ME
RID
IAN
OF
LO
NG
ITU
DE
. TH
E
INN
ER
SC
AL
E F
RO
M A
PA
RA
LL
EL
OF
LA
TIT
UD
E.
090
270
180
000
080
070
060
050
040030
020010 000
260
250
240
230
220210
209 190 180
100
110
120
130
140
150
160170 180
280
290
300
310
320
330
340350 360
170
160
150
140
130
350
340
330
320
310
190
200
210
220
230
010
020
030
040
050
1258
Constant Latitude Scale Small Area Plotting Sheet
Plot 1258 DR at: L 44º 50.6’ N Lo 92º 21.2’ W
30’
45ºN
30’
20’
10’
50’
40’
30’
92ºW10’30’20’
40’50’ 50’
1258
STEP 5 With sun intercept
4.0nm towards and azimuth 205º, plot your estimated position
THE
OU
TER
SC
ALE
IS R
EA
D F
RO
M A
ME
RID
IAN
OF
LON
GIT
UD
E. T
HE
INN
ER
SC
ALE
FR
OM
A P
AR
ALL
EL
OF
LATI
TUD
E.
090
270
180
000
080
070
060050
040 030 020 010
260
250
240230
220 210 209 190180
100
110
120
130
140
150
160
170
180
280
290
300
310
320
330
340
350
360
170
160
150140
130
350
340
330 320 310
190
200
210
220
230
010
020
030
040
050
1258 Sun
EP L 44º 47.0’ N Lo 092º 24.5’ W
Constant Latitude Scale Small Area Plotting Sheet30’
45ºN
30’
20’
10’
50’
40’
30’
92ºW10’30’20’
40’50’ 50’
1258 GPS
1258 Sun
EP L 44º 47.0’ N Lo 092º 24.5’ W
Sight reduced from FIX: Not an EP, do
not draw a square
Sight Error (SErr) intersection of LOP and azimuth
S Err 4.0nm
1111
Celestial FixesCelestial 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
45ºN
30’
20’
10’
50’
40’
30’
45ºN
30’
20’
10’
50’
40’
30’
Advancing a LOP using a construction line that parallels the DR track
0800
Sun
1200
Sun
0800-1200
Sun1200 RFix
C 260
S 6.0C
200
S 6
.0
0800
0900
1000
1100
1200
18nm @ 260
6nm @ 200
Plotting a Celestial R FixPlotting a Celestial R Fix
0800 @ 0.9nm T 245º 1200 @ 0.8nm A 332º
45ºN
30’
20’
10’
50’
40’
30’
45ºN
30’
20’
10’
50’
40’
30’
0800
Sun
1200
Sun
0800-1200
Sun1200 RFix
C 2
00
S 6
.0
0800
0900
1000
1100
1200
Advancing a LOP using direction and distance between DR’s.
Plotting a Celestial R FixPlotting a Celestial R Fix
C 260
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 050040
030
020
010000
260 250 240 230220
210
209190
180
100
110
120
130
140
150
160
170
180
280
290
300
310
320
330
340
350
360
170 160 150 140130
350 340 330 320 310190
200
210
220
230
010
020
030
040
050
0800 @ 0.9nm T 245º 1200 @ 0.8nm A 332º
45ºN
30’
20’
10’
50’
40’
30’
45ºN
30’
20’
10’
50’
40’
30’
0800
Sun
1200
Sun
0800-1200
Sun1200 RFix
C 2
00
S 6
.0
0800
0900
1000
1100
1200
Advancing a LOP using the original intercept and azimuth
Plotting a Celestial R FixPlotting a Celestial R Fix
C 260
S 6.0
0800 @ 0.9nm T 245º 1200 @ 0.8nm A 332º
Sight Folder PlottingSight Folder Plotting
45ºN
30’
20’
10’
50’
40’
30’
93ºW 30’50’40’
20’10’ 10’
1245
Sun
085
8S
un
0858-1245GPS
S Err 3.6nm
1245 RFix
Sight Folder PlottingSight Folder Plotting
45ºN
30’
20’
10’
50’
40’
30’
93ºW 30’50’40’
20’10’ 10’
1245
Sun
085
8S
un
0858GPS
S Err 4.0nm
085
8-
124
5S
un
1245 RFix
1245GPS
Changing position where sights taken.
Resulting RFix must still be within 5.0nm of later sight.
1717
Offshore: plotting & labeling of courses & Offshore: plotting & labeling of courses & bearings – referenced to bearings – referenced to TRUETRUE Universal plotting sheets used in any Universal plotting sheets used in any
part of the ocean except Polar Regionspart of the ocean except Polar Regions Likely to cross several lines of variation Likely to cross several lines of variation
offshore.offshore. Using True, apply Var & Dev for each leg Using True, apply Var & Dev for each leg
to determine Compass course to steer.to determine Compass course to steer.
Universal Plotting SheetsUniversal Plotting Sheets
1818
Universal Plotting SheetsUniversal Plotting Sheets The UPS covers about
4° of latitude and 4° of longitude
Draw meridian through marks on Compass Rose at desired mid-latitude
1919
Universal Plotting SheetsUniversal Plotting Sheets Setup for mid-latitude of 37° N
and mid-longitude of 68° WT
HE
OU
TE
R S
CA
LE
IS R
EA
D F
RO
M A
ME
RID
IAN
OF
LO
NG
ITU
DE
. TH
E
INN
ER
SC
AL
E F
RO
M A
PA
RA
LL
EL
OF
LA
TIT
UD
E.
090
270
180
000
080070
060050
040030
020010000
260250
240230
220210
209190180100
110
120
130
140
150
160170180
280290
300
310
320
330
340350360
170160
150140
130
350340
330320
310
190200
210
220
230
010020
030
040
050
30
7
30
7
Will be used for chapter 13 homework cruise
2020
Setup for mid-latitude of 37° N and mid-longitude of 68° W
Universal Plotting SheetsUniversal Plotting Sheets
Set dividers to the spacing between central meridian and the one drawn
Measure off and draw remaining meridians
Label
68ºW69º70º 66º67º
37ºN
38º
39º
36º
35º
2121
Universal Plotting SheetsUniversal Plotting Sheets68ºW69º70º 66º67º
37ºN
38º
39º
36º
35º
Distance & latitude -measured along Latitude scale on central meridian
Longitude - measured on pre-printed scale
draw line across at value of mid-lat
35º 36º 37º 38º 39º
2222
Longitude MeasurementsLongitude Measurements Measure 15’ of Longitude
at 37° Latitude. Precision on UPS – 1.0nm or
1’ of Latitude/Longitude.
10’ 5’+
2323
Universal Plotting SheetsUniversal Plotting Sheets68ºW69º70º 66º67º
37ºN
38º
39º
36º
35º
(ZD+5) (ZD+4)
Time Zone Boundaries Vertical dashed line, with ZD on
both sides
15º W Var
Isogonic Lines Lines of equal magnetic variation Dashed line, with variation shown
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…
15º W Var
YOU WILL USE THIS UPS FOR PLOTTING THE CHAPTER 13 HOMEWORK CRUISE
2424
Universal Plotting SheetsUniversal Plotting Sheets68ºW69º70º 66º67º
37ºN
38º
39º
36º
35º
(ZD+5) (ZD+4)15º W Var
15º W Var
DOUBLING THE SCALE
37ºN
30’
38º
30’
36º
68ºW30’69º 67º30’(ZD+5) (ZD+4)15º W
Var
15º W Var
5
10
15
20
25
2525
Meridian TransitMeridian Transit 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
Observer
GP SunEquator
Greenwich
Pn
Meridian Transit of Sun also known as
Local Apparent Noon (LAN)
2626
Finding Time of TransitFinding Time of Transit
Mean time of transit is calculated
2727
Find ZT of MT on 14 Find ZT of MT on 14 Nov at Lo 092° 21.2Nov at Lo 092° 21.2´W´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
092 21.2
Finding Time of TransitFinding Time of Transit
2828
092 21.2
Step 3 Record GHA
Step 4 Subtract whole
hour GHA from DR Lo
Step 5 Browse increments
/ corrections pages
18
092 10.9
0 10.3
Finding Time of TransitFinding Time of TransitFind ZT of MT on 14 Find ZT of MT on 14 Nov at Lo 092° 21.2Nov at Lo 092° 21.2´W´W
2929
Step 6 Record increment
Step 7 Add to GHA whole
hour
Step 5 Correct for ZD
00 4118 00
41612 00 41
+
ZD: 21.2’ / 60 = 0.3533
092.3533º / 15 = 6.15
Finding Time of TransitFinding Time of TransitFind ZT of MT on 14 Find ZT of MT on 14 Nov at Lo 092° 21.2Nov at Lo 092° 21.2´W´W 092
21.218
092 10.9
0 10.3
3030
The Ultimate BackupThe 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
Computing LatitudeComputing Latitude
3131
Computing LatitudeComputing 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
3232
Observer North of Sun
50°N
50°S
Equator
CoAlt
Sun
Observer70201030
Computing LatitudeComputing Latitude
3333
50°N
50°S
Equator
CoAlt
Sun
Observer
Computing LatitudeComputing Latitude
Observer South of Sun
30602040
3434
Taking the Noon SightTaking 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 sightsHelpful to plot run of sights
3535
Latitude from MT SightLatitude from MT Sight DR position on DR position on 20 20
AprilApril:: L 48° 54.0´ NL 48° 54.0´ N Lo 125° 26.0´ WLo 125° 26.0´ W
From a series of From a series of sights around noon, sights around noon, you selected the you selected the maximum observed maximum observed altitude altitude hs of sun (LL) is hs of sun (LL) is
52° 28.9´52° 28.9´ at at 12–18–2612–18–26. .
WE WE 2s slow2s slow. . HE HE 10.210.2 feet, IC feet, IC +1.2+1.2´́
20
20 29
8+12-20-29
125 25 0120 17 8
5 07 2
20-20-29
20 Apr 201212-18-26
02+12-18-28
8+20-18-2820 Apr
48 54 0
2
125 26 0
10 252 28 9
1 23 13 11 2
1 9–52 27 0
15 2
52 42 2+
20 11 45 9
+ 0 3+ 0 9
11 46 2
Sun
52 42 237 17 811 46 249 04 048 54 0
10 0C
o-A
lt You
What’s your azimuth angle?
3636
Meridian Transit of the SunMeridian Transit of the SunEnd ofEnd of
Junior NavigationJunior Navigation
Chapter 9Chapter 9
Bring your Pilot Chart next Bring your Pilot Chart next week andweek and
Begin Preparing Sight Begin Preparing Sight FoldersFolders