1. Emergency Navigation Quiz
Global Navigation
Chapter 7

2. Question 1
A vessel travels 30nm on course 045° from L30°32' N, Lo 40°43' W. What is the approximate latitude and longitude at the point of arrival?
Réponse : L30°53’N, Lo040°20’W

3. Question 2
29 october
GHA Aries 1500 hour °16,6’
14 m 58 s °45,1’
GHA Aries °01,7’
SHA Sirius °39,6’
Sub-total °41,3’
- 360°
GHA Sirius °41,3’
Since your latitude = Sirius declination, your latitude is approximately L16°43,0’S.
From the Nautical Almanac, you find that the SHA Sirius is 258°39,6’, and its declination is 16°43,0’S.
At UT on 29 October 20XX, you identify Sirius directly overhead. What is your position?
Solution:
Since Sirius is directly overhead, you are at GP of the body. To find your latitude and longitude, convert Sirius’ celestial coordinates for that date and time to terrestrial coordinates.
UT october
29 october
Since GHA<180°, GHA = Lo W, so your longitude is approximately Lo165°41,3’W.
To obtain longitude, calculate the GHA Sirius at the time of the sighting:
GHA Sirius = GHA (Aries) + SHA (Arcturus)
Answer : L16°43,0’, Lo165°41,3’W.

4. Emergency Navigation Quiz
End of
Global Navigation
Chapter 7