Pass Benchmark: 70% (21/30) • Standard: USCG NMC / 46 CFR
USCG Navigation Problems (Set 2)
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Question 1 of 30
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 162°T at a sextant altitude (hs) of 28°36.5'. 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?
Browse Questions in Set 2
30 MCQs #1 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 162°T at a sextant altitude (hs) of 28°36.5'. 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? #2 On 9 February your 0830 zone time DR position is LAT 22°19.0'N, LONG 64°37.0'E. Your vessel is on course 128°T at a speed of 19.0 knots. What is the zone time of local apparent noon? #3 On 12 February your 0930 zone time DR position is LAT 25°20.0'N, LONG 30°40.0'W. Your vessel is on course 135°T at a speed of 11.2 knots. What is the zone time of local apparent noon (LAN)? #4 You observe the lower limb of the Sun at a sextant altitude (hs) of 62°22.2' on 6 June. The index error is 1.2' on the arc. The height of eye is 28 feet (8.5 meters). What is the observed altitude (Ho)? #5 On 3 October your 0830 ZT position is LAT 26°15.0'S, LONG 73°16.0'E. Your vessel is on course 280°T at a speed of 19.0 knots. What is the ZT of local apparent noon (LAN)? #6 On 22 February your 1857 DR position is LAT 23°46.0'S, LONG 93°16.5'E. You observe an unidentified star bearing 108°T at an observed altitude (Ho) of 67°53.9'. The chronometer reads 01h 00m 35s, and is 03m 25s fast. What star did you observe? #7 The true course between two points is 078°. Your gyrocompass has an error of 2°E. You make an allowance of 3° leeway for a north wind. What gyro course should be steered to make the true course good? #8 On 2 October your 1845 DR position was LAT 28°09.2'S, LONG 167°48.1'E. You observe a faint star through a hole in the clouds at a sextant altitude (hs) of 20°45.6' T, bearing 201.5°T. The index error is 1.3' off the arc, and the height of eye is 42 feet. The chronometer reads 07h 46m 19s and is 00m 51s fast. What star did you observe? #9 On 15 November your 0813 zone time (ZT) fix gives you a position of LAT 22°30.0'N, LONG 67°28.0'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 49°46.0'. What is the latitude at 1200 ZT? #10 On 10 October your 1500 zone time DR position is LAT 27°35.6' S, LONG 44°49.0' W. You are on course 342°T at a speed of 24 knots. Considering their magnitude, azimuth, and altitude, which group includes the three bodies best suited for a fix at star time? #11 On 22 June your 0424 DR position is LAT 26°18.5' N, LONG 124°18.2' W. You observe an unidentified star bearing 154°T at an observed altitude (Ho) of 15°01.2'. The chronometer reads 12h 23m 24s, and is 01m 32s slow. What star did you observe? #12 On 7 March at 1838 ZT, in DR position LAT 34°26.9' N, LONG 58°16.2' W, you observe Polaris for latitude. The sextant altitude (hs) is 35°08.4'. The index error is 2.5' off the arc. The height of eye is 54 feet. What is the latitude at the time of the sight? #13 On 16 January at 1804 zone time, you take a sextant observation of Polaris. Your vessel's DR position is LAT 36°12' N, LONG 124°36' W, and your sextant reads (hs) 37°16.4'. Your chronometer reads 02h 02m 12s, and is 01m 36s slow. Your height of eye is 60 feet, and the index error is 1.5' on the arc. From your observation of Polaris, what is the latitude of your vessel? #14 If the pitch of the propeller is 26.7 feet, and the revolutions per day are 131,717, calculate the day's run allowing 4% negative slip. #15 If the pitch of the propeller is 19.4 feet, and the revolutions per day are 96,713, calculate the day's run allowing 6% positive slip. #16 On 25 April your 1130 DR position is LAT 24°50.0'N, LONG 61°25.0'W. Your vessel is on a course of 300°T at a speed of 16.0 knots. Determine the zone time of (LAN) for your vessel. #17 At 1300 ZT on 9 May your DR position is LAT 24°00'N, LONG 83°26'W. 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 07h 00m 00s. #18 Your vessel is steering course 166°psc, variation for the area is 8°W, and deviation is 3°W. The wind is from the west-southwest, producing a 2° leeway. What true course are you making good? #19 You desire to make good a true course of 329°. The variation is 13° W, magnetic compass deviation is 4°E, and gyrocompass error is 2°W. A southerly wind produces a 1° leeway. What is the course to steer per standard magnetic compass to make the true course good? #20 If the speed necessary for reaching port at a designated time is 17.4 knots and the pitch of the propeller is 25.6 feet, how many revolutions per minute will the shaft have to turn, assuming a 3% positive slip? #21 On 3 December evening twilight for your vessel will occur at 1901 zone time. Your vessel's DR position will be LAT 24°18.5' S, LONG 110°30.6' W. Considering their magnitude and location, what are the three stars best suited to observe for a fix at star time? #22 If the pitch of the propeller is 25.1 feet, and the revolutions per day are 91,591, calculate the day's run allowing 7% positive slip. #23 If the speed necessary for reaching port at a designated time is 23.7 knots and the pitch of the propeller is 20.8 feet, how many revolutions per minute will the shaft have to turn, assuming a 7% negative slip? #24 On 12 June your 1945 DR position is LAT 21°47.0'N, LONG 46°52.0'W when you observe a faint unidentifiable star through a break in the clouds. The star bears 130°T at a sextant altitude (hs) of 45°21.2'. The index error is 0.5' on the arc, and the height of eye is 45 feet. The chronometer reads 10h 43m 27s, and the chronometer error is 1m 46s slow. What star did you observe? #25 On 28 July your 0800 zone time fix gives you a position of LAT 25°16.0'N, LONG 71°19.0'W. Your vessel is on course 026°T, and your speed is 17.5 knots. Local apparent noon (LAN) occurs at 1149 zone time, at which time a meridian altitude of the Sun's lower limb is observed. The observed altitude (Ho) for this sight is 82°28.7'. What is the calculated latitude at LAN? #26 The true course between two points is 057°. Your gyrocompass has an error of 3° east and you make an allowance of 1° leeway for a north-northwest wind. Which gyro course should be steered to make the true course good? #27 On 2 January you are on a course of 094°T at a speed of 20 knots. At 0430 ZT, your DR position is LAT 24°12'N, LONG 71°24'W. Determine the zone time of sunrise. #28 On 3 February your 0451 zone time DR position is LAT 24°15.0' S, LONG 124°24.0' W. Considering their magnitude, azimuth and altitude, which group includes the three bodies best suited for a fix at star time? #29 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 313°T at a sextant altitude (hs) of 14°56.3'. 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? #30 On 16 July your 1810 zone time DR position is LAT 24°16.5' S, LONG 162°52.0' E. Considering their magnitude, azimuth, and altitude, which group includes the three bodies best suited for a fix at star time?
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