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A las 10h 00m del 25 de marzo de 2023, navegando al Rumbo verdadero 340º, nos encontramos al Sur verdadero del faro de Cabo Trafalgar y obtenemos marcación al faro de Punta Camarinal 110º ER. Situados, damos rumbo para pasar a 5 millas del faro de Cabo Roche. Calcular el rumbo de aguja, sabiendo que la declinación magnética es 4º NW y que el desvío de la aguja es +4º (más)At 10h 00m on 25 March 2023, steering true course 340º due South true of Cape Trafalgar with Punta Camarinal bearing 110º Starboard, you set course to pass 5 miles off Cabo Roche (variation 4º NW, deviation +4º). What is the compass course?
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Correct answer: c) 316º
Why it is correct
With Rv = 340º and relative bearing 110º starboard, Dv(Camarinal) = 340º + 110º − 360º = 090º (due west of Camarinal and due south of Trafalgar: 36º 05.4′ N, 006º 02.0′ W). From there, the tangent to pass 5 miles off Cabo Roche is Rv = 316º; since Ct = −4º + 4º = 0º, Ra = 316º.
Why the others are not
- a) Does not match the tangent to the 5-mile arc off Cabo Roche (Rv = Ra = 316º).
- b) Does not match the tangent to the 5-mile arc off Cabo Roche (Rv = Ra = 316º).
- d) Does not match the tangent to the 5-mile arc off Cabo Roche (Rv = Ra = 316º).
How to work it out in the exam
- Fix the vessel due south of Trafalgar (006º 02.0′ W) and due west of Camarinal (Dv = 090º, l = 36º 05.4′ N).
- Draw the tangent to the 5-mile arc off Cabo Roche: Rv = 316º, and with Ct = 0º, Ra = 316º.
Where this question comes from
- Junta de Andalucía · 2023 · 1ª convocatoria · PER Modelo A · question 45 Official paper · Official answer key
- Junta de Andalucía · 2023 · 1ª convocatoria · PER Modelo B · question 43 Official paper · Official answer key
Try it: Navigation calculations
Pending instructor review. Machine translation, not reviewed.