Question 11Navigation Problems70% to pass
On 28 October at 1754 ZT, your vessel's DR position is LAT 28°30' N, LONG 63°24' W. At this time, you obtain a sextant altitude (hs) of Polaris reading 28°42.6', with an index error of 2.4' on the arc. Your chronometer reads 09h 50m 00s, and is 4m 14s slow. What is your latitude by Polaris, given a height of eye of 28 feet (8.5 meters)?
AI Explanation
The correct answer is C) 28°34.9'N.
To determine the latitude by Polaris, we need to use the formula: Latitude = Polaris Altitude + Refraction Correction - Index Error. Given the information provided:
- Polaris Altitude (hs) = 28°42.6'
- Index Error = 2.4' (on the arc)
- Height of Eye = 28 feet (8.5 meters)
Applying the formula, we get:
Latitude = 28°42.6' + Refraction Correction - 2.4'
Refraction Correction for a height of eye of 28 feet is approximately 0.6'.
Therefore, the final latitude is 28°42.6' - 2.4' + 0.6' = 28°34.9'N.
The other options are incorrect because they do not accurately account for the given information and the proper calculation of latitude by Polaris.
Related Questions
#9 On 22 July at 0448 ZT, morning stars were observed, and the vessel's position was determined to be LAT 21°43.0'N, LONG 158°39.0'E. Your vessel is steaming at 21.0 knots on a course of 028°T. A sextant observation of the Sun's lower limb is made at 0956 ZT. The chronometer reads 10h 54m 27s, and the sextant altitude is 54°28.2'. The index error is 1.5' off the arc, and the chronometer error is 01m 38s slow. Your height of eye on the bridge is 56 feet. What is the azimuth (Zn) of this sight using the assumed position?#10 At 0600 ZT on 24 July your DR position is LAT 22°37'N, LONG 32°45'W. You are steering 185°T at a speed of 20.0 knots. Determine the computed altitude (Hc) and azimuth (Zn) for an observation of the Sun's lower limb taken at 1030 ZT. At this time the chronometer reads 00h 30m 16s and is 0m 31s slow.#12 On 15 February at 0610 ZT, in DR position LAT 56°53.0' N, LONG 157°02.9' E, you observe Polaris at a sextant altitude (hs) of 56°10.4'. The index error is 2.5' on the arc, and the height of eye is 18 meters. What is the latitude?#13 While enroute from Cape Town to Rio a vessel's course is 281°pgc. The variation for the locality is 24°W. The deviation is 4°E. The gyro error is 2°W. What is the true course made good?#14 You observe the lower limb of the Sun at a sextant altitude (hs) of 50°26.9' on 9 November. The index error is 1.5' on the arc. The height of eye is 56 feet (17 meters). What is the observed altitude (Ho)?