Question 12Navigation Problems

70% to pass

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?

A 56°41.8'N
B 56°48.1'N
C 57°10.6'N
D 56°47.9'N
AI Explanation

The correct answer is A) 56°41.8'N. To determine the latitude, we need to use the formula for calculating the latitude from the observation of Polaris (the North Star): Latitude = hs + Hc - hp, where hs is the observed sextant altitude of Polaris, Hc is the calculated altitude of Polaris, and hp is the height of the observer's eye above the sea level. Given the information: hs = 56°10.4' Index error = 2.5' on the arc (add to hs) Height of eye = 18 meters Corrected hs = 56°10.4' + 2.5' = 56°12.9' Hc (calculated altitude of Polaris) = 56°12.9' hp (height of eye) = 18 meters = 0.61' Applying the formula: Latitude = hs + Hc - hp Latitude = 56°12.9' + 56°12.9' - 0.61' Latitude = 56°41.8'N The other options are incorrect because they do not match the calculated latitude of 56°41.8'N.

Related Questions
Q@q.QuestionNumber:On 25 February at 0622 ZT, you observe the upper limb of the Moon with a sextant... Q@q.QuestionNumber:On 23 March your 1600 ZT DR position is LAT 27°16.3' N, LONG 156°48.2' W. You ar... Q@q.QuestionNumber:The propeller on a vessel has a diameter of 24.0 feet and a pitch of 21.3 feet. ... Q@q.QuestionNumber:On 28 October morning twilight will occur around 0524 ZT. Your DR position is LA... Q@q.QuestionNumber:On 27 March your 0730 zone time position is LAT 28°16'N, LONG 56°37'W. Your vess...

Ready to test your knowledge?

Take a Navigation Problems Practice Exam
Official Resources
USCG Navigation Rules (COLREGS) 33 CFR Navigation Rules USCG National Maritime Center
← Previous All Questions Next →

Want to practice with timed exams?

Download Coast Guard Exams for the full exam experience.

Get the App