NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Exercise #15
From: Jeremy C
Date: 2008 Jun 15, 15:39 EDT
Vote for your city's best dining and nightlife. City's Best 2008.
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From: Jeremy C
Date: 2008 Jun 15, 15:39 EDT
Giuseppe,
You did very well. All of your answers are well within
tolerance. To answer your specific questions, our magnetic compass is very
much in need of alignment. The captain will not let me touch it, so we
live with up to 16 degrees of deviation on the intercardinal points. I
know it would be a fairly simple adjustment of the quadrantal spheres to at
least reduce the deviation, but it is his ship. I will try to remember to
take a photo of our deviation card before I go later this week.
As far as "best fix" for 1900, you would rightly think that adding the PM
moon and sun would increase accuracy and it would. I will post my solution
with a jpg of the plot in the next few days. A big change on the ship
occurred yesterday and I will be very busy.
This exercise is similar to one of our examination elements, except in the
US, the exercise is a terrestrial exercise instead of celestial.
In a message dated 6/15/2008 8:03:22 P.M. West Pacific Standard Time,
menga@polito.it writes:
All refraction correction under standard conditionsestim pos at 12h 15° 14'N, 145° 0.5'E distance run 36 nm
estim pos at 12h 23m 20s 15° 14'N, 144° 55.6'Eby estimating departures at 12h 23m 20s dep = deltaLong/COS(Lat) = 40.7 nm
speed made good is 13 kn
with this new speed the estim. pos. at 12h 23m 20s is corrected to 15° 13.5'N, 144° 54.8'E
From previous fix DR position at 16h 03m 42s is 15° 13.5'N, 144° 5.3'E Sun Zn 287.5° (compass Least error East)286.4-287.5 = -1.1° (east) error of gyro
deviation of the magnetic compass for course 275 dev = 286-274.6+1.3 = +12.7 W (isn't too much??)
DR at 16h 45m 15°N 13.52' 143°E 56.09'
Twilight at sunset (LMT) GMT = LMT - 143.9/15 (8h 54m)
(LMT) sunset start end Sun Zn
18:29:59 18:53:39 19:21:35 294°13.35'
stars (middle of the twilight) Date and time 10.6.2008 09:06:00 UT; G.H.A. Aries : 35°35.71
Mag. Name Const./SD G.H.A. decl. S.H.A. Zn Azimuth h altitude L.H.A. HP
to EAST
0.2 Arcturus alBoo 181°34.58' 19° 8.26' 145°58.88' 78°11.47' 56°52.29' 325°30.66'
0.1 Vega alLyr 116°16.83' 38°47.33' 80°41.13' 50°13.91' 2° 6.17' 260°12.91'
to South
0.9 Hadar beCen 184°28.82' -60°25.15' 148°53.12' 164°46.10' 10°13.04' 328°24.90'
0.1 Rigil Kent alCen 175°32.45' -60°52.52' 139°56.75' 161°24.37' 7°19.76' 319°28.54'
to North
1.7 Alioth epUMa 201°59.19' 55°55.00' 166°23.49' 11°43.93' 47°54.06' 345°55.27'
to West
-11.7Moon 15.40 228°30.30' 3° 4.63' 192°54.60' 226°28.69' 72°44.63' 12°26.38' 56.50863'1.5 Mars 0.04 255°10.47' 16°52.77' 219°34.77' 278° 1.91' 52°26.34' 39° 6.56'
0.7 Saturn 0.14 240° 5.01' 12° 2.01' 204°29.31' 265°11.94' 66°27.25' 24° 1.09'
0.6 Betelgeuse alOri 306°41.43' 7°24.58' 271° 5.73' 277°18.86' 1°20.54' 90°37.51'
0.5 Procyon alCMi 280°39.66' 5°12.24' 245° 3.96' 268°25.72' 25°51.16' 64°35.74'
1.3 Regulus alLeo 243°23.31' 11°55.57' 207°47.61' 266°19.27' 63°15.27' 27°19.39'
-1.6 Sirius alCMa 294°13.10' -16°43.65' 258°37.40' 250°38.35' 6°33.19' 78° 9.19'
Compass checking at twilight Gyro error 294.7- 294.2 = 0.5° W, magnetic compass deviation at 180° -10° (E) ?
Fix at 18h 15m 14°N 55.31' 143°E 59.68'
Fix by adding Sun, Moon and stars observations assuming 13 kn speed and 180° course at 19:0014°N 45.99' 143°E 59.66'
Fix by using only the two stars14°N 51.29' 144°E 2.58'
which of the two is the best?It is like a licence examination, however I used my program instead of the tables - How did I perfom, did I pass it, can I apply for a position?
Giuseppe
Vote for your city's best dining and nightlife. City's Best 2008.
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