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El 10 de marzo de 2018 al ser HRB = 11h00m nos encontramos en situación verdadera 36º 00´ N y 005º 50´W y damos rumbo al puerto de Tánger (punto de llegada Luz de la farola del espigón) a 4 nudos de velocidad. Declinación magnética = 3º NW y desvío de la aguja = +3º (más). Se pide Rumbo de aguja y HRB de llegada a Tánger.On 10 March 2018 at 11h 00m in true position 36º 00' N, 005º 50' W, you set course for the port of Tangier (breakwater light) at 4 knots (variation = 3º NW, deviation = +3º). Find the compass course and ETA at Tangier:
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Correct answer: d) Ra = 171º and HRB = 14h 09m
Why it is correct
From 36º 00.0′ N, 005º 50.0′ W to the Tangier breakwater light (35º 47.4′ N, 005º 48.2′ W), Rv = 171º and distance d = 12.6 miles. Since Ct = −3º + 3º = 0º, Ra = 171º; at 4 knots the run takes 12.6 / 4 = 3h 09m, arriving at 14h 09m.
Why the others are not
- a) Does not match Rv = Ra = 171º (Ct = 0º) and the 3h 09m run time for 12.6 miles at 4 knots.
- b) Does not match Rv = Ra = 171º (Ct = 0º) and the 3h 09m run time for 12.6 miles at 4 knots.
- c) Does not match Rv = Ra = 171º (Ct = 0º) and the 3h 09m run time for 12.6 miles at 4 knots.
How to work it out in the exam
- Measure on the chart from 36º 00′ N, 005º 50′ W to Tangier breakwater: Rv = 171º and d = 12.6 miles.
- With Ct = 0º (Ra = 171º), divide d / v = 12.6 / 4 = 3h 09m and add to 11h 00m: 14h 09m.
Where this question comes from
- Junta de Andalucía · 2018 · 1ª convocatoria · PER Modelo A · question 45 Official paper · Official answer key
- Junta de Andalucía · 2018 · 1ª convocatoria · PER Modelo B · question 44 Official paper · Official answer key
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Pending instructor review. Machine translation, not reviewed.