Pass Benchmark: 70% (21/30) • Standard: USCG NMC / 46 CFR
USCG Navigation Problems (Set 4)
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Question 1 of 30
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 27°17.0' S, LONG 83°17.0' E. Considering their magnitude and location, what are the three stars best suited to observe for a fix at star time?
Browse Questions in Set 4
30 MCQs #1 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 27°17.0' S, LONG 83°17.0' E. Considering their magnitude and location, what are the three stars best suited to observe for a fix at star time? #2 On 1 October you determine the zone time of evening twilight will be 1835. Your DR position will be LAT 27°18.0' N, LONG 48°52.0' W. Considering their magnitude and location, which group of three stars are best suited to be used in obtaining a fix at star time? #3 On 22 March your 1834 ZT DR position is LAT 26°13.5' S, LONG 108°36.5' W. You observe an unidentified star bearing 077°T, at an observed altitude (Ho) of 43°10.5'. The chronometer reads 01h 32m 37s and is 01m 50s slow. What star did you observe? #4 On 3 February your 0550 zone time DR position is LAT 26°16.0' N, LONG 112°05.0' W. Considering their magnitude, azimuth, and altitude, which group includes the three bodies best suited for a fix at star time? #5 On 11 March your 1846 zone time DR position is LAT 25°05.7' N, LONG 124°29.0' W. At that time you observe Polaris with a sextant altitude (hs) of 25°59.1'. The chronometer time of the sight is 02h 44m 01s, and the chronometer error is 02m 15s slow. The index error is 3.9' on the arc, and the height of eye is 42.7 feet (13.0 meters). What is your latitude by Polaris? #6 On 22 May your 0437 ZT DR position is LAT 25°18.5' N, LONG 51°18.0' W. You observe an unidentified star bearing 097°T at an observed altitude (Ho) of 48°20.0'. The chronometer reads 07h 40m 40s and is 03m 24s fast. What star did you observe? #7 On 27 March your 0330 zone time DR position is LAT 23°32'N, LONG 154°47'E. Your vessel is on a course of 105°T at a speed of 20 knots. What will be the zone time of sunrise at your vessel? #8 If the speed necessary for reaching port at a designated time is 16.8 knots and the pitch of the propeller is 22.3 feet, how many revolutions per minute will the shaft have to turn, assuming a 4% negative slip? #9 You observe the lower limb of the Sun at a sextant altitude (hs) of 46°20.3' on 1 April. The index error is 4.5' off the arc. The height of eye is 57 feet (17.4 meters). What is the observed altitude (Ho)? #10 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 019.0°T at a sextant altitude (hs) of 53°56.2'. 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? #11 From 1020, 3 March, to 1845, 5 March, your vessel steamed an observed distance of 845.6 miles. The average RPM was 78, and the pitch of the propeller was 20'03". What was the slip? #12 On 24 July your 1912 zone time DR position is LAT 24°28.0' N, LONG 73°46.5' W. Considering their magnitude, azimuth, and altitude, which group includes the three stars best suited for a fix at star time? #13 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 282.5°T at a sextant altitude (hs) of 14°22.3'. 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? #14 On 16 July your 1920 ZT DR position is LAT 25°36.0' N, LONG 172°18.9' W. Considering their magnitude, azimuth, and altitude, which group includes the three bodies best suited for a fix at star time? #15 On 14 January your 0550 ZT DR position is LAT 25°26.0' N, LONG 38°16.0' W. You observe an unidentified star bearing 004.5°T, at an observed altitude (Ho) of 40°10.0'. The chronometer reads 08h 48m 51s and is 01m 22s slow. What star did you observe? #16 On 17 November your 1530 ZT DR position is LAT 27°13.0'S, LONG 153°21.0'W. You are on course 261°T at a speed of 14 knots. What will be the ZT of sunset at your vessel? #17 On 14 January your 1922 ZT DR position is LAT 27°18.5' S, LONG 67°18.0' E. You observe an unidentified star bearing 029°T, at an observed altitude (Ho) of 29°35.0'. The chronometer reads 03h 25m 43s and is 03m 15s fast. What star did you observe? #18 Your 0830 DR position is LAT 27°33'S, LONG 79°17'E. Your vessel is on a course of 066°T, at a speed of 19.5 knots. Determine the time of LAN on 10 December. #19 At 1000 ZT 21 October your DR position is LAT 29°00'N, LONG 134°40'E. Determine the computed altitude (Hc) of the Sun for the assumed position nearest to the above given latitude and longitude, given a chronometer time of 01h 00m 00s. #20 You observe the lower limb of the Sun at a sextant altitude (hs) of 22°58.6' on 16 June. The index error is 2.0' off the arc. The height of eye is 61 feet. What is the observed altitude (Ho)? #21 At 0520 zone time on 17 March, while taking stars for a morning fix, you observe an unidentified star bearing 050°T, at an observed altitude (Ho) of 45°00.0'. Your DR position at the time of the sight is LAT 27°23.0'N, LONG 39°42.0' W. The chronometer time of the sight is 08h 22m 15s, and the chronometer error is 01m 45s fast. Your vessel is steaming on a course of 300°T at a speed of 18 knots. What star did you observe? #22 On 1 November your 1600 zone time DR position is LAT 27°48'S, LONG 91°26'E. Your vessel is on a course of 327° T at a speed of 16 knots. What will be the zone time of sunset at your vessel? #23 On 30 August your 0554 zone time (ZT) position was LAT 25°39.0'S, LONG 31°51.0'E. Your vessel was steaming on course 325°T at a speed of 15.0 knots. An observation of the Sun's lower limb was made at 0836 ZT. The chronometer read 06h 38m 36s and was fast 02m 24s. The observed altitude (Ho) was 30°49.2'. LAN occurred at 1157 ZT. The observed altitude (Ho) was 56°40.0'. What was the longitude of your 1157 ZT running fix? #24 If the pitch of the propeller is 20.6 feet, and the revolutions per day are 107,341, calculate the day's run allowing 3% positive slip. #25 On 13 June your 0445 DR position is LAT 20°12.0' N, LONG 44°45.0' W. You observe an unidentified star bearing 168°T at an observed altitude (Ho) of 38°56.0'. The chronometer reads 07h 43m 20s, and is 01m 39s slow. Which star did you observe? #26 On 8 April your evening DR position is LAT 22°16' N, LONG 157°58.3' W. You observe an unidentified star bearing 246°T at an observed altitude (Ho) of 58°45.5'. The chronometer reads 05h 09m 57s, and is 01m 23s slow. What star did you observe? #27 On 8 April your evening DR position is LAT 22°16.0' N, LONG 157°58.3' W. You observe an unidentified star bearing 271°T at an observed altitude (Ho) of 44°08.2'. The chronometer reads 05h 09m 57s, and is 01m 23s slow. What star did you observe? #28 On 17 January your 0730 zone time fix gives you a position of LAT 22°26.0'S, LONG 152°17.0'E. Your vessel is steaming on a course of 116°T at a speed of 17 knots. An observation of the Sun's lower limb is made at 1015 zone time. The chronometer reads 00h 13m 23s, and the chronometer error is 01m 49s slow. The observed altitude (Ho) is 66°02.1'. LAN occurs at 1152 zone time and a meridian altitude of the Sun's lower limb is made. The observed altitude (Ho) is 87°54.2'. Determine the vessel's 1200 zone time position. #29 The propeller on a vessel has a diameter of 18.8 feet and a pitch of 21.4 feet. What would be the slip if the vessel cruised 378 miles in a 24 hour day (observed distance) at an average RPM of 76? #30 On 1 December your 1600 ZT DR position is LAT 22°48.0'S, LONG 91°26.0'E. You are on course 327°T at a speed of 16 knots. What will be the zone time of sunset at your vessel?
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