Pass Benchmark: 70% (21/30) • Standard: USCG NMC / 46 CFR
USCG Navigation Problems (Set 3)
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Question 1 of 30
The propeller on a vessel has a diameter of 21.5 feet and a pitch of 24.5 feet. What would be the apparent slip if the vessel cruised 458 miles in a 23 hour day (observed distance) at an average RPM of 78?
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30 MCQs #1 The propeller on a vessel has a diameter of 21.5 feet and a pitch of 24.5 feet. What would be the apparent slip if the vessel cruised 458 miles in a 23 hour day (observed distance) at an average RPM of 78? #2 On 26 November your 0535 DR position is LAT 27°18.9' S, LONG 30°18.4' E. You observe an unidentified planet bearing 085°T at an observed altitude (Ho) of 32°15.2'. The chronometer reads 03h 33m 16s, and is 01m 48s slow. What planet did you observe? #3 On 15 October your 0300 zone time DR position is LAT 27°14' S, LONG 99°46' E. You are on course 128°T at a speed of 19 knots. Considering their magnitude, azimuth, and altitude, which group includes the three bodies best suited for a fix at star time? #4 On 13 November at 0438 ZT, morning stars were observed and the vessel's position was determined to be LAT 22°14.0'S, LONG 79°23.0'E. Your vessel is steaming at 13.0 knots on a course of 242°T. A sextant observation of the Sun's lower limb is made at 0822 ZT. The chronometer reads 03h 20m 16s, and the sextant altitude (hs) is 45°49.7'. The index error is 1.0' on the arc, and the chronometer error is 01m 47s slow. Your height of eye on the bridge is 61.0 feet (18.6 meters). What is the azimuth (Zn) of this sight using the assumed position? #5 On 5 May your 1800 ZT DR position is LAT 26°11.5'N, LONG 65°35.0'W. You are on course 270°T at a speed of 12 knots. What will be the ZT of sunset at your vessel? #6 On 10 June your 1712 zone time DR position is LAT 25°10.0' S, LONG 06°58.0' E. You are on course 213°T at a speed of 9.0 knots. Considering their magnitude, azimuth, and altitude, which group includes the three stars best suited for a fix at star time? #7 On 16 March your 0330 ZT DR position is LAT 22°36.0'S, LONG 76°16.0'E. You are on course 098°T at a speed of 16 knots. What will be the ZT of sunrise at your vessel? #8 On 7 May you observe Polaris for latitude at 0303 ZT. Your DR position is LAT 56°35.4' N, LONG 05°38.9' W. The sextant altitude is 56°11.1'. The height of eye is 36', and the index error is 3.3' off the arc. What is the latitude at the time of the sight? #9 On 24 March your vessel is enroute from Cadiz to Norfolk. Evening twilight will occur at 1830 zone time and your vessel's DR position will be LAT 35°06' N, LONG 60°48' W. Considering their azimuth, altitude, and magnitude, which group of stars is best suited for plotting a star fix at star time? #10 On 6 March your 1854 zone time DR position is LAT 23°51.5' N, LONG 73°14.0' W. At that time you observe Polaris with a sextant altitude (hs) of 24°16.5'. The chronometer time of the sight is 11h 52m 40s, and the chronometer error is 01m 56s slow. The index error is 5.0' on the arc, and the height of eye is 43.5 feet (13.3 meters.) What is your latitude by Polaris? #11 On 3 February your 0547 zone time DR position is LAT 24°18.5' N, LONG 167°25.0' E. Considering their magnitude, azimuth, and altitude, which group includes the three bodies best suited for a fix at star time? #12 On 12 September your 0600 zone time (ZT) fix gives you a position of LAT 22°51.9'N, LONG 133°40.1'W. Your vessel is on course 062°T, and your speed is 12.3 knots. Local apparent noon (LAN) occurs at 1142 ZT, at which time a meridian altitude of the Sun's upper limb is observed. The observed altitude (Ho) for this sight is 70°33.2'. What is the calculated latitude at LAN? #13 On 10 October your 0930 zone time position is LAT 25°00.0'S, LONG 164°38.6'W. Your vessel is on course 180°T at a speed to 10.0 knots. What is the zone time of local apparent noon (LAN)? #14 On 2 October your 1845 DR position is 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 25°19.4' bearing 273°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 0m 51s fast. What star did you observe? #15 You are turning 105 RPM, with a propeller pitch of 17 feet, and an estimated slip of -1%. What is the speed of advance? #16 On 22 April your 1852 ZT DR position is LAT 23°54.5' N, LONG 117°36.8' W. You observe an unidentified star bearing 129°T at an observed altitude (Ho) of 27°10.0'. The chronometer reads 02h 54m 53s and is 02m 51s fast. What star did you observe? #17 On 4 January your 0800 zone time DR position is LAT 25°25.0 S, LONG 16°09.0'W. Your vessel is on course 290°T at a speed of 13.5 knots. What is the zone time of local apparent noon (LAN)? #18 On 11 November your 0200 zone time DR position is LAT 26°32' S, LONG 154°16' E. You are on course 058°T at a speed of 21 knots. Considering their magnitude, azimuth, and altitude, which group includes the three bodies best suited for a fix at star time? #19 On 28 October morning twilight will occur around 0524 ZT. Your DR position is LAT 25°25.0' N, LONG 32°33.3' W. Considering their magnitude and location, which group will be the three stars best suited to observe for a star fix at star time? #20 On 17 May at 0501 zone time, morning stars were observed, and the vessel's position was determined to be LAT 22°16.0'S, LONG 103°46.0'W. Your vessel is steaming at 24.0 knots on a course of 301°T. A sextant observation of the Sun's lower limb is made at 0845 zone time. The chronometer reads 03h 43m 32s, and the sextant altitude is 28°24.7'. The index error is 1.5' off the arc, and the chronometer error is 02m 02s slow. Your height of eye on the bridge is 85.5 feet. What is the azimuth (Zn) of this sight using the assumed position? #21 On 14 January your 0550 DR position is LAT 25°26.0'N, LONG 38°16.0'W. You observe an unidentified star bearing 212°T at an observed altitude (Ho) of 41°42.3'. The chronometer reads 08h 48m 51s, and is 01m 22s slow. What star did you observe? #22 On 22 July your 1759 ZT DR position is LAT 24°50.2' S, LONG 05°16.0' E. You observe an unidentified star bearing 231°T, at an observed altitude (Ho) of 26°10.0'. The chronometer reads 06h 01m 31s and is 02m 15s fast. What star did you observe? #23 On 23 March your 1600 ZT DR position is LAT 27°16.3' N, LONG 156°48.2' W. You are on course 063°T at a speed of 18.0 knots. Considering their magnitude, azimuth, and altitude, which group includes the three stars best suited for a fix at star time? #24 On 24 September your 1841 zone time DR position is LONG 129°34.5' E. At that time you observe Polaris with a sextant altitude (hs) of 25°20.8'. The chronometer time of the sight is 09h 38m 12s, and the chronometer error is 03m 12s slow. The index error is 4.3' off the arc, and the height of eye is 52 feet (15.9 meters). What is your latitude by Polaris? #25 On 20 June your 1742 zone time DR position is LAT 24°55.0' S, LONG 8°19.6' E. Considering their magnitude, azimuth, and altitude, which three stars are best suited for a fix at star time? #26 On 30 October an ex-meridian altitude of the Sun's lower limb at upper transit was observed at 1144 ZT. Your DR position is LAT 22°42.0'S, LONG 137°16.0'W, and your sextant altitude (hs) is 80°59.4'. The index error is 2.5' off the arc, and your height of eye is 42.5 feet. The chronometer time of the observation is 08h 46m 15s, and the chronometer error is 02m 12s fast. Find the latitude at meridian transit from the ex-meridian observation. #27 On 22 July your 1759 DR position is LAT 24°50.2' S, LONG 05°16.0' E. You observe an unidentified star bearing 293°T at an observed altitude (Ho) of 17°52.8'. The chronometer reads 06h 01m 31s, and is 02m 15s fast. What star did you observe? #28 On 22 July your 0442 DR position is LAT 26°35.6' N, LONG 22°16.7' W. You observe an unidentified star bearing 149°T at an observed altitude (Ho) of 12°55.0'. The chronometer reads 05h 39m 03s, and is 03m 14s slow. What star did you observe? #29 On 12 July your 0800 ZT DR position is LAT 24°15.0'N, LONG 132°30.0'W. Your vessel is on course 045°T at a speed of 15.0 knots. What is the ZT of local apparent noon (LAN)? #30 On 16 February your 0300 ZT DR position is LAT 28°32.0'S, LONG 176°49.0'E. You are on course 082°T at a speed of 21 knots. What will be the zone time of sunrise at your vessel?
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