Emergency Navigation Quiz Global Navigation Chapter 7

Question 1 A vessel travels 30nm on course 045° from L30°32' N, Lo 40°43' W. What is the approximate latitude and longitude at the point of arrival? Réponse : L30°53’N, Lo040°20’W

Question 2 29 october GHA Aries 1500 hour 263°16,6’ 14 m 58 s 3°45,1’   GHA Aries 15-14-58 267°01,7’ SHA Sirius 258°39,6’ Sub-total 525°41,3’ - 360° GHA Sirius 165°41,3’ Since your latitude = Sirius declination, your latitude is approximately L16°43,0’S. From the Nautical Almanac, you find that the SHA Sirius is 258°39,6’, and its declination is 16°43,0’S. At UT 15-14-58 on 29 October 20XX, you identify Sirius directly overhead. What is your position?   Solution: Since Sirius is directly overhead, you are at GP of the body. To find your latitude and longitude, convert Sirius’ celestial coordinates for that date and time to terrestrial coordinates. UT 15-14-58 29 october 29 october Since GHA<180°, GHA = Lo W, so your longitude is approximately Lo165°41,3’W. To obtain longitude, calculate the GHA Sirius at the time of the sighting: GHA Sirius = GHA (Aries) + SHA (Arcturus) Answer : L16°43,0’, Lo165°41,3’W.

Emergency Navigation Quiz End of Global Navigation Chapter 7