National Maritime Center

Transcription

1 National Maritime Center Providing Credentials to Mariners Q207 Navigation Problems-Oceans (Sample Examination) Page 1 of 6

2 Choose the best answer to the following Multiple Choice questions. 1. On 1 December your 1600 ZT DR position is LAT 'S, LONG 'E. You are on course 327 T at a speed of 16 knots. What will be the zone time of sunset at your vessel? o (A) 1823 (B) 1827 o (C) 1831 o (D) During twilight on 28 December around 1800 GMT, in DR position LAT 4 00'N, LONG 0 06'W, the sextant altitude (hs) of Venus was '. The height of eye was 36 feet, and the index error was 2.0' on the arc. The temperature was 68 F. The barometer read 1030 mb. Calculate the observed altitude (Ho). o (A) Ho ' o (B) Ho ' (C) Ho ' o (D) Ho ' If choice C is selected set score to You desire to make good a true course of 038. The variation is 5 E, magnetic compass deviation is 4 W, and gyrocompass error is 4 W. A southeasterly wind produces a 4 leeway. What is the course to steer per standard magnetic compass to make the true course good? o (A) 047 psc (B) 041 psc o (C) 043 psc o (D) 033 psc 4. On 24 August your vessel is enroute from Perth, Australia, to Bombay, India. Evening twilight will occur at 1807 zone time and your vessel's DR position will be LAT ' S, LONG ' E. Considering their magnitude and location, what are the three stars best suited to observe for a fix at star time? o (A) Arcturus, Antares, Atria o (B) Pollux, Canopus, Hamal (C) Spica, Altair, Acrux o (D) Rasalhague, Spica, Kochab If choice C is selected set score to 1. Page 2 of 6

3 5. A vessel at LAT 07 05'N, LONG 81 45'W is to proceed to LAT 08 40'N, LONG 88 00'W. What are the course and distance by mid-latitude sailing? o (A) T, miles (B) T, miles o (C) T, miles o (D) T, miles 6. ( ) On 18 May your 1030 ZT DR position is LAT 18 30'N, LONG 62 31'W. You are on course 286 T, speed 24 knots. Determine your 1200 position using the following observations of the Sun. Zone Time GHA Declination Ho ' N ' ' ' N ' ' o (A) LAT 'N, LONG 'W o (B) LAT 'N, LONG 'W o (C) LAT 'N, LONG 'W (D) LAT 'N, LONG 'W 7. You are on a great circle track departing from LAT 'N, LONG 'W and your initial course is T. The position of the vertex is LAT 'N, LONG 'W. What is the distance along the great circle track between the point of departure and the vertex? o (A) miles o (B) miles (C) miles o (D) miles If choice C is selected set score to 1. Page 3 of 6

4 8. On 14 January your 0746 zone time DR position is LAT 'N, LONG 'W. At that time, you observe the Sun bearing 123 psc. The chronometer reads 05h 49m 16s, and the chronometer error is 02m 29s fast. The variation is 3 W. What is the deviation of the standard magnetic compass? (A) 1.4 W o (B) 1.6 E o (C) 3.4 E o (D) 4.4 W 9. On 15 November your 0813 zone time (ZT) fix gives you a position of LAT 'N, LONG 'W. Your vessel is on course 164 T, and your speed is 13.5 knots. Local apparent noon (LAN) occurs at 1215 ZT, at which time a meridian altitude of the Sun's lower limb is observed. The observed altitude (Ho) for this sight is '. What is the latitude at 1200 ZT? (A) 'N o (B) 'N o (C) 'N o (D) 'N 10. ( ) On 4 December your 1500 ZT DR position is LAT ' N, LONG ' W. You are on course 020 T at a speed of 15.0 knots. You observed 3 celestial bodies. Determine the latitude and longitude of your 1548 running fix. Body Zone Time GHA Observed Altitude Declination Venus ' ' S ' Sun L/L ' ' S ' Moon L/L ' ' S ' o (A) LAT 'N, LONG 'W o (B) LAT 'N, LONG 'W o (C) LAT 'N, LONG 'W (D) LAT 'N, LONG 'W Page 4 of 6

5 11. On 12 June your 1845 DR position is LAT 21 47'N, LONG 46 52'W when you observe a faint unidentifiable star through a break in the clouds. The star bears 270 T at a sextant altitude (hs) of '. The index error is 0.5' on the arc, and the height of eye is 45 feet. The chronometer reads 09h 43m 27s, and the chronometer error is 1m 46s slow. What star did you observe? o (A) Scheat (B) Algeiba o (C) Epsilon Leonis o (D) Merak 12. On 8 April your 0830 zone time DR position is LAT 'N, LONG 'W. Your vessel is on course 228 T at a speed of 19.0 knots. What is the zone time of local apparent noon (LAN)? (A) 1144 o (B) 1147 o (C) 1150 o (D) On 18 November your 1750 zone time DR position is LONG ' W. At that time you observe Polaris with a sextant altitude (hs) of '. The chronometer time of the sight is 00h 52m 43s, and the chronometer error is 02m 18s fast. The index error is 3.2' on the arc, and the height of eye is 49.5 feet. What is your latitude by Polaris? (A) 'N o (B) 'N o (C) 'N o (D) 'N 14. The initial great circle course angle between LAT 23 00'S, LONG 42 00'W and LAT 34 00'S, LONG 18 00'E is What is the true course? o (A) T o (B) T o (C) T (D) T Page 5 of 6

6 15. You are planning a voyage from Cape May (LAT 38 45'N, LONG 74 45'W) to Lisbon (LAT 38 37'N, LONG 09 45'W). Which of the following is TRUE? (Use gnomonic chart WOXZC 5274) o (A) A composite sailing must be plotted to remain south of a limiting latitude of 44 N. o (B) The distance is measured by using the length of one degree of the meridian at the position of the vertex. o (C) Because the latitudes are almost the same, a great circle track approximates a parallel sailing. (D) The northern hemisphere vertex is approximately at longitude 42 26'W. Page 6 of 6