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Re: Exercise #15 Day's Run (almost)
From: Giuseppe Menga
Date: 2008 Jun 14, 22:32 +0200
From: Giuseppe Menga
Date: 2008 Jun 14, 22:32 +0200
Jeremy, On my account at 14�14' N (the course is due west, so no change of latitude) on the meridian passage the 10-6-2008 (decl. 23� 1.91'N) the height of the sun was 81�12.10', taking into account all corrections Hs should be almost 1� lower than yours. Did I do something wrong? Giuseppe ----- Original Message ----- From: "Anabasis"To: "NavList" Sent: Saturday, June 14, 2008 10:26 AM Subject: [NavList 5443] Exercise #15 Day's Run (almost) Exercise #15 Day�s Run (almost) There has been some request from members of the group to have an �old school� exercise where �DR�s� are actual dead reckoning positions and not GPS fixes; giving us a bit of ambiguity as to where the vessel was at the time of the sight. This exercise should fit that description. The scenario is departing anchorage and then heading out to sea, where position and other celestial checks will be done throughout the day. The only given position will be the departure point, and all sights will be based on the previous reductions and running DR tracks. This scenario is the exact trip we made on 10 June 2008 from departure until the end of my evening watch at 20h 00m. For all sights, height of eye is 106 ft, Index error is 0.0. All times are local zone time, and the ship is keeping ZD-10. The local date is 10 June 2008. A ship takes departure from the Saipan anchorage at 9h 00m local time. Position is fixed by visual and radar LOP�s and is determined to be Lat 14deg 14.0� N; Longitude 145deg 38� East. The ship steams on a course of 270 deg True at making turns (engine speed) for 12.0 knots. At 10h 25m 59s, a lower limb observation of the sun is made. Hs is 62deg 22.4�. Temp is 85deg F Pressure is 1010 MB. At 12h 19m LAN is observed. The Hs of the lower limb of the sun is 82deg 06.0�. Temp is 98 deg F Pressure is 1010 MB. Soon after LAN, the navigator sees that the moon has risen and takes an observation of the upper limb of the moon. Hs is 6deg 20.8� at 12h 23m 20s. Determine a running 12h 00m fix (noon position). Also determine distance run as well as course and speed made good since departure. At 16h 03m 42s a PM Azimuth of the Sun is observed on the starboard gyro repeater. The sun�s observed bearing is 286.4 degrees PGC. The course PGC is 273.5 degrees, Variation from the chart is 1.3 degrees East. Course per magnetic steering compass is 286.0 degrees. Determine Gyro error and Deviation on this heading. At 1645 the ship alters course to 180 degrees true, maintaining 12.0 knots. At 17h 25m 20s, a lower limb observation of the sun is made. Temp is 95deg Pressure is 1010MB. Hs is 18deg 55.6� Star time approaches, determine sunset, time of stars, determine LHA of Aries, and select stars to be shot. Around 18h 15m, the moon approaches Meridian Transit (LAM). The following data is collected: Moon UL: Hs 78deg 34.9� at 18h 11m 58s Moon UL: Hs 78deg 37.5� at 18h 13m 03s Moon UL: Hs 78deg 37.2� at 18h 13m 41s Moon UL: Hs 78deg 36.4� at 18h 14m 20s Moon UL: Hs 78deg 37.2� at 18h 14m 46s Moon UL: Hs 78deg 36.1� at 18h 15m 27s Moon UL: Hs 78deg 35.7� at 18h 16m 12s Moon UL: Hs 78deg 35.4� at 18h 16m 42s Moon UL: Hs 78deg 34.2� at 18h 17m 10s Moon UL: Hs 78deg 33.4� at 18h 17m 42s Sun UL: Hs 7deg 27.2� at 18h 18m 33s Sun UL: Hs 7deg 15.8� at 18h 19m 17s Sun UL: Hs 7 deg 08.8� at 18h 19m 50s Sun UL: Hs 7 deg 01.2� at 18h 20m 27s Determine the 18h 15m fix. As the sun was near setting, an amplitude was observed on the Celestial Horizon. The sun�s bearing was 294.7 degrees. The ship was steering 180 PGC, 168 per magnetic compass, and the variation off of the chart was 1.3 degrees East. Determine Magnetic Deviation at this heading. PM star time was poor with clouds and a hazy horizon. Only two bodies were observed. Temp was 84 deg F, pressure is 1010MB. Arcturus was shot at 19h 20m 51s Hs is 60deg 34.0� Dubhe was observed at 19h 13m 53s Hs is 41deg 58.6. Determine the 1900 star fix. Have fun Jeremy --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---