El día 26 de abril, al ser Hrb= 10:30, encontrándonos en la enfilación Punta Paloma-Isla Tarifa, tomamos demora de aguja a Punta Alcazar 184º. Situados damos rumbo de aguja Ra= 267º. Teniendo en cuenta que la velocidad de la embarcación es 7 nudos, se pide la situación estimada al ser Hrb= 12:00. Desvío= 1,5º(-) y la declinación magnética en toda la zona es 2,5º W.At 10:30 on the Punta Paloma–Isla Tarifa leading line, you observe Da Punta Alcázar = 184º, then steer Ra = 267º at 7 knots (deviation –1.5º, variation 2.5º W). What is your estimated position at 12:00?

Correct answer: c) l = 35º 57.2' N; L = 005º 46.4' W.

Why it is correct

With Ct = −2.5º − 1.5º = −4º, Dv(Alcázar) = 184º − 4º = 180º, intersecting the Punta Paloma–Isla Tarifa leading line SE of Tarifa at 35º 58.5′ N, 005º 33.4′ W. Running 1.5 h at 7 knots (10.5 miles) on Rv = 267º − 4º = 263º brings you at 12:00 to l = 35º 57.2′ N, L = 005º 46.4′ W.

Why the others are not

• a) Does not match running 10.5 miles on Rv = 263º from the intersection of the Paloma–Tarifa alignment with due north of Alcázar.
• b) Does not match running 10.5 miles on Rv = 263º from the intersection of the Paloma–Tarifa alignment with due north of Alcázar.
• d) Does not match running 10.5 miles on Rv = 263º from the intersection of the Paloma–Tarifa alignment with due north of Alcázar.

How to work it out in the exam

1. With Ct = −4º, Dv(Alcázar) = 180º: intersect the Paloma–Tarifa alignment at 35º 58.5′ N, 005º 33.4′ W.
2. Plot 10.5 miles (1.5 h at 7 knots) on Rv = 267º − 4º = 263º: 35º 57.2′ N, 005º 46.4′ W.

Where this question comes from

• Ministerio de Transportes (Madrid) · 2025 · Convocatoria de abril · PER Test 2 · question 43 Official paper · Official answer key
• Ministerio de Transportes (Madrid) · 2025 · Convocatoria de abril · PER Test 4 · question 45 Official paper · Official answer key

Try it: Navigation calculations

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