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Navegamos al rumbo verdadero 227º a 5,1 nudos de velocidad. A HRB 14:00 nos encontramos en la enfilación de los faros de Punta Europa y Punta Carnero y a 6 millas del faro de Punta Europa. A HRB 16:00 nos encontramos al Sur verdadero del faro de Punta Europa y al Este verdadero del faro de la Isla de Tarifa. Calcular el rumbo de la corriente e intensidad horaria de la misma.Steaming on Rv = 227º at 5.1 knots, at HRB 14:00 you are on the Punta Europa–Punta Carnero leading line at 6 miles from Punta Europa, and at HRB 16:00 you are due South of Punta Europa and due East of Isla de Tarifa. Find Rc and Ihc:
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Correct answer: d) Rc = SE; Ihc = 1.5'
Why it is correct
Starting at 14:00 6 miles NE of Punta Europa on the Carnero–Europa leading line (36º 09.1′ N, 005º 14.0′ W), 2 hours at 5.1 knots (10.2 miles along 227º) puts the 16:00 DR at 36º 02.1′ N, 005º 23.2′ W. The 16:00 observed fix (due South of Europa, due East of Tarifa) is 36º 00.0′ N, 005º 20.7′ W. From DR to fix is 3.0 miles towards SE (135º) ⇒ Ihc = 3.0 / 2 = 1.5 knots.
Why the others are not
- a) Does not divide the 3.0-mile drift by the 2 hours elapsed or reverses the direction.
- b) Does not divide the 3.0-mile drift by the 2 hours elapsed or reverses the direction.
- c) Does not divide the 3.0-mile drift by the 2 hours elapsed or reverses the direction.
How to work it out in the exam
- Plot 10.2 miles along Rv = 227º from the start to find the 16:00 DR (36º 02.1′ N, 005º 23.2′ W).
- Join DR to fix (36º 00.0′ N, 005º 20.7′ W): Rc = SE and d = 3.0′ in 2 h ⇒ Ihc = 1.5 knots.
Where this question comes from
- Junta de Andalucía · 2016 · 2ª convocatoria · PY Módulo de navegación · question 15 Official paper · Official answer key
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Pending instructor review. Machine translation, not reviewed.