Grunt Productions 2007
Time, Rise/Set and Time, Rise/Set and Gyro ChecksGyro Checks
Using data in the Nautical Using data in the Nautical AlmanacAlmanac
A brief by Lance GrindleyA brief by Lance Grindley
Grunt Productions 2007
CoveringCovering
Time and time zones including Time and time zones including questions on passage planning.questions on passage planning.
Rising and setting, twilights and Rising and setting, twilights and Moonrise or MoonsetMoonrise or Moonset
Gyro checks at Sunrise or Sunset Gyro checks at Sunrise or Sunset using the True Amplitude Tables using the True Amplitude Tables (Nories)(Nories)
Grunt Productions 2007
Earth’s Annual OrbitEarth’s Annual Orbit
Winter Solstice
Summer Solstice
Grunt Productions 2007
Earth’s RotationEarth’s Rotation
Earth rotates 360Earth rotates 360oo in 24 hours = in 24 hours = 1515oo per hour. per hour.
The Sun moves through 15The Sun moves through 15oo of of longitude every hour - called Arc to longitude every hour - called Arc to Time.Time.
Used as a basic division of Used as a basic division of Standard Time Zones which are Standard Time Zones which are divided into areas 15° in longitude divided into areas 15° in longitude across.across.
Grunt Productions 2007
Uniform Time SystemUniform Time System Conceived to ensure all vessels at sea Conceived to ensure all vessels at sea
within same area are keeping the within same area are keeping the same zone timesame zone time
Based on Solar Day 360Based on Solar Day 360oo in 24 hours in 24 hours gives 15gives 15oo per hour per hour
Zones are described in ALRS Vol. 2 Zones are described in ALRS Vol. 2 page 255page 255
Ships may not necessarily keep to Ships may not necessarily keep to these Standard Time Zonesthese Standard Time Zones
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Standard Time ZonesStandard Time Zones
Grunt Productions 2007
Time Zone Time Zone ConventionsConventions
Time zones usually designated Time zones usually designated numerically by indicating correction numerically by indicating correction to zone time to obtain GMTto zone time to obtain GMT
Easterly zones negative, westerly Easterly zones negative, westerly zones positivezones positive
May be indicated by letter Z for May be indicated by letter Z for GMT, A to M increasing easterly GMT, A to M increasing easterly (omitting J), N to Y increasing (omitting J), N to Y increasing westerlywesterly
Grunt Productions 2007
Standard Time Zones (1)Standard Time Zones (1)Greenwich
71/2oW 71/2
oE 221/2oE 371/2
oE221/2oW371/2
oW
12001100100009000800
(-2)B
(-1)A
(0)Z
(+1)N
(+2)O
Grunt Productions 2007
Standard Time Zones (2)Standard Time Zones (2)Greenwich
71/2oW 71/2
oE 221/2oE 371/2
oE221/2oW371/2
oW
13001200110010000900
(-2)B
(-1)A
(0)Z
(+1)N
(+2)O
Grunt Productions 2007
Standard Time Zones (3)Standard Time Zones (3)Greenwich
71/2oW 71/2
oE 221/2oE 371/2
oE221/2oW371/2
oW
14001300120011001000
(-2)B
(-1)A
(0)Z
(+1)N
(+2)O
Grunt Productions 2007
Standard Time Zones (4)Standard Time Zones (4)Greenwich
71/2oW 71/2
oE 221/2oE 371/2
oE221/2oW371/2
oW
15001400130012001100
(-2)B
(-1)A
(0)Z
(+1)N
(+2)O
Grunt Productions 2007
Standard Time Zones (5)Standard Time Zones (5)Greenwich
71/2oW 71/2
oE 221/2oE 371/2
oE221/2oW371/2
oW
16001500140013001200
(-2)B
(-1)A
(0)Z
(+1)N
(+2)O
Grunt Productions 2007
Some Definitions of TimeSome Definitions of Time
Universal Time (UT1) is the Mean Solar Universal Time (UT1) is the Mean Solar Time of the prime meridian obtained by Time of the prime meridian obtained by direct astronomical observationdirect astronomical observation
Greenwich Mean Time generally equivalent Greenwich Mean Time generally equivalent to UT1 and used to define angular position to UT1 and used to define angular position relative to the prime meridianrelative to the prime meridian
International Atomic Time (TA1) based on International Atomic Time (TA1) based on Cesium clock - very accurate but not Cesium clock - very accurate but not corrected for polar variation - hence leap corrected for polar variation - hence leap secondsseconds
Grunt Productions 2007
Legal TimeLegal Time
Decreed time zone for each territory.Decreed time zone for each territory. May not conform to the longitude as May not conform to the longitude as
legal time is adjusted for political and legal time is adjusted for political and commercial reasons.commercial reasons.
Many countries employ daylight saving Many countries employ daylight saving time (DST) when clocks are advanced by time (DST) when clocks are advanced by one hour.one hour.
Dates for DST must be checked in the Dates for DST must be checked in the Table of Legal Time.Table of Legal Time.
Grunt Productions 2007
Passage CalculationsPassage Calculations
Work out how long the passage will take.Work out how long the passage will take. Add the Time in Hand (TIH)Add the Time in Hand (TIH) This gives total time period of the This gives total time period of the
passagepassage Convert ETA/ETD to ZULU Time.Convert ETA/ETD to ZULU Time. Add/subtract total passage time.Add/subtract total passage time. Convert ETD/ETA to Legal TimeConvert ETD/ETA to Legal Time NB Legal to Zulu follow sign - Zulu to NB Legal to Zulu follow sign - Zulu to
Legal reverse the sign Legal reverse the sign
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Example Example
D14. Your ship is leaving D14. Your ship is leaving WELLINGTON (New Zealand) at 1000 WELLINGTON (New Zealand) at 1000 local time on 7 Feb 98, bound for local time on 7 Feb 98, bound for PANAMA, a distance of 6,480 nautical PANAMA, a distance of 6,480 nautical miles. Allowing a passage speed of miles. Allowing a passage speed of 12 knots, and allowing a zero TIH for 12 knots, and allowing a zero TIH for one hour per day or part of a day, one hour per day or part of a day, also allow 8 hours for refuelling at also allow 8 hours for refuelling at sea, what is your ETA?sea, what is your ETA?
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Example - WorkingExample - Working
6,480nm @ 12 knots = 540 hours = 22d 12h6,480nm @ 12 knots = 540 hours = 22d 12h Time in hand 23 hrs plus 8 hrs = Time in hand 23 hrs plus 8 hrs = 1d 07h1d 07h Total time on passage = 23d 19hTotal time on passage = 23d 19h ETD Wellington 071000(-13) 062100Z FEBETD Wellington 071000(-13) 062100Z FEB Passage +Passage +231900231900 ETA Panama 021600Z MARETA Panama 021600Z MAR Legal Time Zone (+5) Legal Time Zone (+5) -0500-0500 ETA Panama ETA Panama 021100(+5)021100(+5)
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Changing Time ZonesChanging Time Zones
A ship keeping the Standard Time Zone for A ship keeping the Standard Time Zone for 6060oo West is due to arrive at PARAMARIBO West is due to arrive at PARAMARIBO (Suriname). How must the clocks be altered (Suriname). How must the clocks be altered before entering harbour?before entering harbour?
Time Zone for 60Time Zone for 60oo W Zone (+4) W Zone (+4) Time Zone in Suriname (+3)Time Zone in Suriname (+3) Move from 4 hours behind GMT to 3 hours Move from 4 hours behind GMT to 3 hours
behind GMT, therefore clocks behind GMT, therefore clocks advanced by advanced by one hour.one hour.
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Alternative CalculationAlternative Calculation
Ship’s time assumed to be 1200 (+4)
Converted to GMT 1600
New Time Zone Suriname (+3) -3 hours
New time in Zone (+3) 1300
Clocks need to be advanced one hour from 1200 to 1300.
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Sunrise/SunsetSunrise/Sunset
Basis of tabulationsBasis of tabulations. At sunrise and . At sunrise and sunset 16’ is allowed for semi-sunset 16’ is allowed for semi-diameter and 34’ for horizontal diameter and 34’ for horizontal refraction, so that at the times given refraction, so that at the times given the Sun’s upper limb is on the visible the Sun’s upper limb is on the visible horizon; all time refer to the horizon; all time refer to the phenomena as seen from sea level phenomena as seen from sea level with a clear horizon.with a clear horizon.
((Nautical AlmanacNautical Almanac) )
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Northerly DeclinationNortherly Declination
N S
E
W
P
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Southerly DeclinationSoutherly Declination
N S
E
W
P
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Effect of DeclinationEffect of Declination
N S
E
W
P
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Calculating Sunrise/setCalculating Sunrise/set
Obtain times at specified latitudes from Obtain times at specified latitudes from Nautical Almanac.Nautical Almanac.
Interpolate times for the correct latitude.Interpolate times for the correct latitude. If not middle day, check for tri-daily If not middle day, check for tri-daily
change (previous or following page).change (previous or following page). Apply correction for Arc to Time Apply correction for Arc to Time
(longitude).(longitude). Convert time to event from Z to zone Convert time to event from Z to zone
time. time.
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Nautical Almanac Nautical Almanac EntryEntry
Morning Twilights Sunrise
Sunset Evening Twilights
Tabulated Latitudes
Dates 3 Day Period
Grunt Productions 2007
Extract from NA Extract from NA Twilight Moonrise
Lat Naut Civil Sunrise 22 23 24 25h m h m h m h m h m h m h m
N 72 05 29 06 49 08 05 19 01 20 50 22 31 24 08
N 70 05 29 06 41 07 48 19 55 21 23 22 53 24 22 68 05 29 06 34 07 34 20 28 21 48 23 10 24 33 66 05 28 06 29 07 23 20 52 22 06 23 24 24 42 64 05 28 06 24 07 14 21 10 22 21 23 35 24 50 62 05 28 06 20 07 06 21 26 22 34 23 45 24 57 60 05 27 06 16 06 59 21 38 22 44 23 53 25 02
N 58 05 27 06 12 06 53 21 49 22 54 24 00 00 00 56 05 26 06 09 06 48 21 59 23 02 24 06 00 06 54 05 25 06 07 06 43 22 07 23 09 24 12 00 12 52 05 25 06 04 06 39 22 15 23 15 24 17 00 17 50 05 24 06 02 06 35 22 22 23 21 24 22 00 22 45 05 22 05 56 06 26 22 36 23 34 24 32 00 32
N 40 05 20 05 51 06 19 22 48 23 44 24 40 00 40 35 05 17 05 47 06 13 22 58 23 53 24 47 00 47 30 05 15 05 43 06 07 23 07 24 00 00 00 00 53 20 05 09 05 35 05 58 23 23 24 14 00 14 01 04N 10 05 03 05 28 05 49 23 36 24 25 00 25 01 13 0 04 55 05 20 05 41 23 49 24 36 00 36 01 22
S 10 04 46 05 11 05 33 24 01 00 01 00 47 01 31 20 04 35 05 01 05 24 24 14 00 14 00 59 01 40 30 04 20 04 49 05 14 24 30 00 30 01 12 01 51 35 04 10 04 41 05 08 24 39 00 39 01 20 01 57 40 03 58 04 32 05 01 00 04 00 49 01 28 02 04 45 03 44 04 22 04 53 00 17 01 01 01 38 02 12
S 50 03 25 04 09 04 43 00 33 01 15 01 51 02 21 52 03 16 04 02 04 39 00 40 01 22 01 56 02 26 54 03 06 03 55 04 34 00 49 01 29 02 03 02 31 56 02 54 03 47 04 28 00 58 01 37 02 09 02 36 58 02 39 03 38 04 22 01 08 01 47 02 17 02 42S 60 02 22 03 28 04 15 01 20 01 57 02 26 02 49
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Calculation SheetCalculation Sheet
Port.................................. Date.........................................
DR Lat............................. DR Long.............................. Zone........
TIMESHigherLatitude
DifferenceTabularInterval
Daily ChangeLowerLatitudeLatitude Increment Time Diff
Daily Change/Long Corrn Apply correction to SR/SS andtwilights if date is not the middle day
Local Mean Time (LMT) Longitude Correction from Table II isonly applied to MR/MS
Arc to Time (Longitude)
Universal Time (UT/GMT)
Zone ( ) (Change the sign)
ZONE TIME
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Sunset ExampleSunset Example
Date 5 Feb 1997Date 5 Feb 1997 DR Position 48DR Position 48oo 30’N 022 30’N 022oo 20’W 20’W Zone Time (+1)Zone Time (+1) 5050ooNN 16591659 4545ooNN 17121712
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Rising/SettingRising/SettingPort……..……… Date…………..DR Lat…..….. DR Long…….... Zone....
Higher Lat.
Lower Lat.
Latitude Increment
Daily Change/Long Corrn
Local Mean Time (LMT)
Arc to Time (Longitude)
Universal Time (UT/GMT)
Zone ( )(Change sign)
Zone Time
Diff.
Daily Change
Time Diff.
5 Feb 8748o30N 22o20W +1
50oN
45oN
1659
1712-13
Grunt Productions 2007
Table 1 - LatitudeTable 1 - Latitude
TABLES FOR INTERPOLATING SUNRISE, MOONRISE, ETC.TABLE 1-FOR LATITUDE
Tabular Interval Difference between the times for consecutive latitudes10 5 2 5m 10m 15m 20m 25m 30m 35m 40m 45m 50m 55m 60m 1h 05m 1h 10m 1h 15m 1h 20m
‘ ‘ ‘ m m m m m m m m m m m m h m h m h m h m0 30 0 15 0 06 0 0 1 1 1 1 1 2 2 2 2 2 0 02 0 02 0 02 0 021 00 0 30 0 12 0 1 1 2 2 3 3 3 4 4 4 5 05 05 05 051 30 0 45 0 18 1 1 2 3 3 4 4 5 5 6 7 7 07 07 07 072 00 1 00 0 24 1 2 3 4 5 5 6 7 7 8 9 10 10 10 10 102 30 1 15 0 30 1 2 4 5 6 7 8 9 9 10 11 12 12 13 13 13
3 00 1 30 0 36 1 3 4 6 7 8 9 10 11 12 13 14 0 15 0 15 0 16 0 163 30 1 45 0 42 2 3 5 7 8 10 11 12 13 14 16 17 18 18 19 194 00 2 00 0 48 2 4 6 8 9 11 13 14 15 16 18 19 20 21 22 224 30 2 15 0 54 2 4 7 9 11 13 15 16 18 19 21 22 23 24 25 265 00 2 30 1 00 2 5 7 10 12 14 16 18 20 22 23 25 26 27 28 29
5 30 2 45 1 06 3 5 8 11 13 16 18 20 22 24 26 28 0 29 0 30 0 31 0 326 00 3 00 1 12 3 6 9 12 14 17 20 22 24 26 29 31 32 33 34 366 30 3 15 1 18 3 6 10 13 16 19 22 24 26 29 31 34 36 37 38 407 00 3 30 1 24 3 7 10 14 17 20 23 26 29 31 34 37 39 41 42 447 30 3 45 1 30 4 7 11 15 18 22 25 28 31 34 37 40 43 44 46 48
8 00 4 00 1 36 4 8 12 16 20 23 27 30 34 37 41 44 0 47 0 48 0 51 0 538 30 4 15 1 42 4 8 13 17 21 25 29 33 36 40 44 48 0 51 0 53 0 56 0 589 00 4 30 1 48 4 9 13 18 22 27 31 35 39 43 47 52 0 55 0 58 1 01 1 049 30 4 45 1 54 5 9 14 19 24 28 33 38 42 47 51 56 1 00 1 04 1 08 1 1210 00 5 00 2 00 5 10 15 20 25 30 35 40 45 50 55 60 1 05 1 10 1 15 1 20
Grunt Productions 2007
Rising/SettingRising/SettingPort……..……… Date…………..DR Lat…..….. DR Long…….... Zone....
Higher Lat.
Lower Lat.
Latitude Increment
Daily Change/Long Corrn
Local Mean Time (LMT)
Arc to Time (Longitude)
Universal Time (UT/GMT)
Zone ( )(Change sign)
Zone Time
Diff.
Daily Change
Time Diff.
5 Feb 8748o30N 22o20W +1
50oN
45oN
1659
1712-13
-0009 1716 +4/3
+0001
1704
Grunt Productions 2007
Arc to Time Arc to Time
CONVERSION OF ARC TO TIME0 -59 60 -119 120 -179 180 -239 240 -299 300 -359 0 00 0 25 0 50 0 75
h m h m h m h m h m h m m s m s m s m s0 0 00 60 4 00 120 8 00 180 12 00 240 16 00 300 20 00 0 0 00 0 01 0 02 0 031 0 04 61 4 04 121 8 04 181 12 04 241 16 04 301 20 04 1 0 04 0 05 0 06 0 072 0 08 62 4 08 122 8 08 182 12 08 242 16 08 302 20 08 2 0 08 0 09 0 10 0 113 0 12 63 4 12 123 8 12 183 12 12 243 16 12 303 20 12 3 0 12 0 13 0 14 0 154 0 16 64 4 16 124 8 16 184 12 16 244 16 16 304 20 16 4 0 16 0 17 0 18 0 19
5 0 20 65 4 20 125 8 20 185 12 20 245 16 20 305 20 20 5 0 20 0 21 0 22 0 236 0 24 66 4 24 126 8 24 186 12 24 246 16 24 306 20 24 6 0 24 0 25 0 26 0 277 0 28 67 4 28 127 8 28 187 12 28 247 16 28 307 20 28 7 0 28 0 29 0 30 0 318 0 32 68 4 32 128 8 32 188 12 32 248 16 32 308 20 32 8 0 32 0 33 0 34 0 359 0 36 69 4 36 129 8 36 189 12 36 249 16 36 309 20 36 9 0 36 0 37 0 38 0 39
10 0 40 70 4 40 130 8 40 190 12 40 250 16 40 310 20 40 10 0 40 0 41 0 42 0 4311 0 44 71 4 44 131 8 44 191 12 44 251 16 44 311 20 44 11 0 44 0 45 0 46 0 4712 0 48 72 4 48 132 8 48 192 12 48 252 16 48 312 20 48 12 0 48 0 49 0 50 0 5113 0 52 73 4 52 133 8 52 193 12 52 253 16 52 313 20 52 13 0 52 0 53 0 54 0 5514 0 56 74 4 56 134 8 56 194 12 56 254 16 56 314 2056 14 0 56 0 57 0 58 0 59
15 1 00 75 5 00 135 9 00 195 13 00 255 17 00 315 21 00 15 1 00 1 01 1 02 1 0316 1 04 76 5 04 136 9 04 196 13 04 256 17 04 316 21 04 16 1 04 1 05 1 06 1 0717 1 08 77 5 08 137 9 08 197 13 08 257 17 08 317 21 08 17 1 08 1 09 1 10 1 1118 1 12 78 5 12 138 9 12 198 13 12 258 17 12 318 21 12 18 1 12 1 13 1 14 1 1519 1 16 79 5 16 139 9 16 199 13 16 259 17 16 319 21 16 19 1 16 1 17 1 18 1 19
20 1 20 80 5 20 140 9 20 200 13 20 260 17 20 320 21 20 20 1 20 1 21 1 22 1 2321 1 24 81 5 24 141 9 24 201 13 24 261 17 24 321 21 24 21 1 24 1 25 1 26 1 2622 1 28 82 5 28 142 9 28 202 13 28 262 17 28 322 21 28 22 1 28 1 29 1 30 1 31
Grunt Productions 2007
Rising/SettingRising/SettingPort……..……… Date…………..DR Lat…..….. DR Long…….... Zone....
Higher Lat.
Lower Lat.
Latitude Increment
Daily Change/Long Corrn
Local Mean Time (LMT)
Arc to Time (Longitude)
Universal Time (UT/GMT)
Zone ( )(Change sign)
Zone Time
Diff.
Daily Change
Time Diff.
5 Feb 8748o30N 22o20W +1
50oN
45oN
1659
1712-13
-0009 1716 +4/3
+0001
1704
+0129
1833
-0100
1733
Grunt Productions 2007
TwilightTwilight
At the times given for the beginning and At the times given for the beginning and end of twilight, the Sun’s zenith distance is end of twilight, the Sun’s zenith distance is 9696oo for civil, and 102 for civil, and 102oo for nautical twilight. for nautical twilight.
The degree of illumination at the times The degree of illumination at the times given for civil twilight is such that the given for civil twilight is such that the brightest stars are visible and the horizon brightest stars are visible and the horizon is clearly defined.is clearly defined.
At the times given for nautical twilight, the At the times given for nautical twilight, the horizon is in general not visible.horizon is in general not visible.
Nautical AlmanacNautical Almanac
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Twilight ExplainedTwilight Explained
Celestial Horizon
Zenith
Civil Twilight
96o
Nautical Twilight
102o
Grunt Productions 2007
Twilight ExampleTwilight Example
What time will Evening Civil What time will Evening Civil Twilight (ECT) occur on 22Twilight (ECT) occur on 22ndnd October 1997 in position October 1997 in position 3333oo 20’S 042 20’S 042oo 45’E? Give 45’E? Give your answer in Zone Time your answer in Zone Time (-3).(-3).
Grunt Productions 2007
Twilight ExampleTwilight ExamplePort……..……… Date…………..DR Lat…..….. DR Long…….... Zone....
Higher Lat.
Lower Lat.
Latitude Increment
Daily Change/Long Corrn
Local Mean Time (LMT)
Arc to Time (Longitude)
Universal Time (UT/GMT)
Zone ( )(Change sign)
Zone Time
Diff.
Daily Change
Time Diff.
22 Oct 8733o20S 42o45E -3
35oS
30oS
1848
1840+8
+0005 1838 -2/3
-0001
1844
-0251
1553
+0300
1853
Grunt Productions 2007
Moonrise/MoonsetMoonrise/Moonset The times of Moonrise and Moonset generally The times of Moonrise and Moonset generally
become later each day by about 50 minutes.become later each day by about 50 minutes. The “lunar day” is therefore roughly 25 hours The “lunar day” is therefore roughly 25 hours
and the angular movement of the Moon would and the angular movement of the Moon would be about 360/25 = 14.4be about 360/25 = 14.4oo per hour. per hour.
Using arc to time of 15Using arc to time of 15oo per hour is not per hour is not accurate but an allowance can be made called accurate but an allowance can be made called the longitude correction.the longitude correction.
Grunt Productions 2007
Nautical Nautical Almanac Almanac MR/MSMR/MS
Moonrise
Moonset
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Table II - for LongitudeTable II - for Longitude
TABLE II-FOR LONGITUDEDifference between the times for given date and preceding date (for east longitude)
or for given date and following date (for west longitude)1h+ 1h+
LongEast orWest
10m 20m 30m 40m 50m 60m 10m 20m 30m 40m 50m 60m 2h 10m 2h 20m 2h 30m 2h 40m 2h 50m 3h 00m
m m m m m m m m m m m m h m h m h m h m h m h m0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 00 0 00 0 00 0 00 0 00
10 0 1 1 1 1 2 2 2 2 3 3 3 04 04 04 04 05 0520 1 1 2 2 3 3 4 4 5 6 6 7 07 08 08 09 09 1030 1 2 2 3 4 5 6 7 7 8 9 10 11 12 12 13 14 1540 1 2 3 4 6 7 8 9 10 11 12 13 14 16 17 18 19 20
50 1 3 4 6 7 8 10 11 12 14 15 17 0 18 0 19 0 21 0 22 0 24 0 2560 2 3 5 7 8 10 12 13 15 17 18 20 22 23 25 27 28 3070 2 4 6 8 10 12 14 16 17 19 21 23 25 27 29 31 33 3580 2 4 7 9 11 13 16 18 20 22 24 27 29 31 33 36 38 4090 2 5 7 10 12 15 17 20 22 25 27 30 32 35 37 40 42 45
100 3 6 8 11 14 17 19 22 25 28 31 33 0 36 0 39 0 42 0 44 0 47 0 50110 3 6 9 12 15 18 21 24 27 31 34 37 40 43 46 49 52 0 55120 3 7 10 13 17 20 23 27 30 33 37 40 43 47 50 53 57 1 00130 4 7 11 14 18 22 25 29 32 36 40 43 47 51 54 0 58 1 01 1 05140 4 8 12 16 19 23 27 31 35 39 43 47 51 54 0 58 1 02 1 06 1 10
150 4 8 13 17 21 25 29 33 38 42 46 50 0 54 0 58 1 03 1 07 1 11 1 15160 4 9 13 18 22 27 31 36 40 44 49 53 0 58 1 02 1 07 1 11 1 16 1 20170 5 9 14 19 24 28 33 38 42 47 52 57 1 01 1 06 1 11 1 16 1 20 1 25180 5 10 15 20 25 30 35 40 45 50 55 60 1 05 1 10 1 15 1 20 1 25 1 30
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Moonrise Example Moonrise Example (Halifax, Nova Scotia)(Halifax, Nova Scotia)
What is the legal time of What is the legal time of moonrise on 17moonrise on 17thth June in June in Halifax, Nova Scotia?Halifax, Nova Scotia?
From Nories Tables:From Nories Tables: Halifax 44Halifax 44oo 40’N 063 40’N 063oo
34’W 34’W
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Moonrise/MoonsetMoonrise/MoonsetPort…………… Date…………..DR Lat…….. DR Long…….... Zone....
Higher Lat.
Lower Lat.
Latitude Increment
Daily Change/Long Corrn
Local Mean Time (LMT)
Arc to Time (Longitude)
Universal Time (UT/GMT)
Zone ( )(Change sign)
Zone Time
Diff.
Daily Change
Time Diff.
HALIFAX 17 Jun 97
44o 40’N 63o 34’W +3
45oN
40oN
1614
1605
+09
+08 1706 +61min
+11
1624
+0414
2038
+3 -0300
1738
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Example (Wuhu)Example (Wuhu)
What are the legal times What are the legal times of sunset and moonset of sunset and moonset at Wuhu, Yangtse River, at Wuhu, Yangtse River, on 22on 22ndnd October? October?
From Nories Tables:From Nories Tables: Wuhu 31Wuhu 31oo 20’N 118 20’N 118oo 21’E 21’E
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Sunset at WuhuSunset at WuhuPort……..……… Date…………..DR Lat…..….. DR Long…….... Zone....
Higher Lat.
Lower Lat.
Latitude Increment
Daily Change/Long Corrn
Local Mean Time (LMT)
Arc to Time (Longitude)
Universal Time (UT/GMT)
Zone ( )(Change sign)
Zone Time
Diff.
Daily Change
Time Diff.
22 Oct 8731o20N 118o21E -8
35oN
30oN
1715
1721-6
-0001 1724 +3/3
+0001
1721
-0753
0928
+0800
1728
Grunt Productions 2007
Moonset at WuhuMoonset at WuhuPort……..……… Date…………..DR Lat…..….. DR Long…….... Zone....
Higher Lat.
Lower Lat.
Latitude Increment
Daily Change/Long Corrn
Local Mean Time (LMT)
Arc to Time (Longitude)
Universal Time (UT/GMT)
Zone ( )(Change sign)
Zone Time
Diff.
Daily Change
Time Diff.
22 Oct 8731o20N 118o21E -8
35oN
30oN
1215
1206+9
+0002 1117 -49
-0016
1152
-0753
0359
+0800
1159
Grunt Productions 2007
Gyro ChecksGyro Checks Checking the gyro at sunrise/sunset is:Checking the gyro at sunrise/sunset is: Accurate because the sun is on the Accurate because the sun is on the
horizonhorizon Easy to check using Easy to check using True Amplitudes.True Amplitudes. Bearing is taken when the lower limb Bearing is taken when the lower limb
appears to lie a semi diameter above the appears to lie a semi diameter above the horizon.horizon.
The amplitude table is entered with ship’s The amplitude table is entered with ship’s latitude and the declination of the Sun.latitude and the declination of the Sun.
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True and Visible True and Visible Rise/set Rise/set
Celestial Horizon
Visible Horizon
Visible SunriseSunset
True SunriseSunset
Civil Twilight
6 deg
34’
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Celestial SphereCelestial Sphere
Horizon
EquatorPole
Zenith
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Path of the SunPath of the Sun
North
EquatorPole
South
West
East
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AmplitudeAmplitude
North
EquatorPole
South
West
East
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Amplitude (Dec Amplitude (Dec opposite)opposite)
North
EquatorPole
South
West
East
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Elements of CalculationElements of Calculation Convert time to GMTConvert time to GMT Work out declination of the sun Work out declination of the sun
rounding up/down to the nearest rounding up/down to the nearest hour.hour.
Note latitude (given in the Note latitude (given in the question)question)
Find true amplitude using tableFind true amplitude using table Apply amplitude to East/West in Apply amplitude to East/West in
direction of declination.direction of declination.
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Example Example
At about 2000(-11) 0n 15 Jun 97, At about 2000(-11) 0n 15 Jun 97, in DR position 48º 50’N, 164º in DR position 48º 50’N, 164º 30’E, the sun bore 309º when the 30’E, the sun bore 309º when the lower limb was one semi-lower limb was one semi-diameter above the visible diameter above the visible horizon. What was the gyro horizon. What was the gyro error?error?
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Sun’s Sun’s DeclinationDeclination
Sun’s Declination
Sun’s SD and “d” correction
Hourly GMT over three day period
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Example (Working)Example (Working)
Time: Time: 152000(-11) JUN152000(-11) JUN GMT:GMT: 150900Z JUN150900Z JUN Dec:Dec: N23N23oo 18.9’ or 23.3 18.9’ or 23.3oo
Lat:Lat: 4848oo 50’N or 48.8º 50’N or 48.8º
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Amplitude Amplitude Table page Table page
4B-174B-17
Declination
Latitude
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Example (Working)Example (Working)
Time: Time: 152000(-11) JUN152000(-11) JUN GMT:GMT: 150900Z JUN150900Z JUN Dec:Dec: N23N23oo 18.9’ or 23.3 18.9’ or 23.3o o
(page 4A-19)(page 4A-19) Lat:Lat: 4848oo 50’N or 48.8º 50’N or 48.8º Amp:Amp: W 37W 37oo N N Bearing:Bearing: 270270oo + 37 + 37oo = 307 = 307oo
Error:Error: 309309ooG/307G/307ooT = 2T = 2oo HIGH HIGH
Grunt Productions 2007
Amplitude DiagramAmplitude Diagram
Declination North
Declination South
N
S
EW
- ve
+ve
+ve
- ve
Grunt Productions 2007
FormulaFormula
Sine DeclinationSine Amplitude =Cosine Latitude
Grunt Productions 2007
Any Questions?Any Questions?