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Un buque navega a Ra= 117º y toma Da de Tarifa= 025º y Marcación de Punta Alcázar = 035º Er, Si la dm= 2º NW y el desvío= -2º calcular la posición en ese momento.A ship steering Ra = 117º takes a compass bearing of Tarifa Da = 025º and a relative bearing of Punta Alcázar = 035º Starboard (variation 2º NW, deviation –2º). Calculate its position:
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Correct answer: d) l = 35º 57.0' N and L = 005º 37.8' W
Why it is correct
With Ct = −2º − 2º = −4º, Rv = 117º − 4º = 113º, Dv(Tarifa) = 025º − 4º = 021º and Dv(Alcázar) = 113º + 35º = 148º. Plotting their reciprocals from Tarifa (201º) and Alcázar (328º) intersects at l = 35º 57.0′ N, L = 005º 37.8′ W.
Why the others are not
- a) Does not match the charted intersection of Dv(Tarifa) = 021º and Dv(Alcázar) = 148º.
- b) Does not match the charted intersection of Dv(Tarifa) = 021º and Dv(Alcázar) = 148º.
- c) Does not match the charted intersection of Dv(Tarifa) = 021º and Dv(Alcázar) = 148º.
How to work it out in the exam
- Compute Ct = −4º, Rv = 113º, Dv(Tarifa) = 021º and Dv(Alcázar) = 148º.
- Plot the position lines from both lights: they intersect at 35º 57.0′ N, 005º 37.8′ W.
Where this question comes from
- Junta de Andalucía · 2021 · 2ª convocatoria · PER Modelo B · question 44 Official paper · Official answer key
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Pending instructor review. Machine translation, not reviewed.