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A HRB= 0605, se encuentran en situación estimada= 36º 10'N – 005º 14'W y le toman azimut de aguja a la estrella Polar (supuesta en el Polo)= 354º Desde esa posición dan rumbo al puerto de Ceuta (luz verde del extremo del espigón de poniente del puerto) a motor con velocidad de máquinas de 8 nudos, teniendo en cuenta la corriente de la zona con Rc= N76E e Intensidad horaria de la corriente de Ihc= 3 nudos. Calculan el rumbo de aguja a Ceuta:At HRB 0605 in DR position 36º 10' N – 005º 14' W, you observe Polaris at compass azimuth 354º and head for Ceuta (green entrance light) at 8 knots in a current Rc = N76E at Ihc = 3 knots. Calculate the compass course to Ceuta:
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Correct answer: c) 207º
Why it is correct
With Polaris at true north, Ct = 360º − 354º = +6º. From 36º 10′ N, 005º 14′ W to Ceuta green light (35º 53.8′ N, 005º 18.6′ W) the effective course is Ref = 193º. With a 3-knot current setting 076º and Vm = 8 knots, the current triangle gives Rv = 213º, so Ra = 213º − 6º = 207º.
Why the others are not
- a) Does not subtract total compass error Ct = +6º from the true heading Rv = 213º obtained from the current triangle.
- b) Does not subtract total compass error Ct = +6º from the true heading Rv = 213º obtained from the current triangle.
- d) Does not subtract total compass error Ct = +6º from the true heading Rv = 213º obtained from the current triangle.
How to work it out in the exam
- Find Ct = 360º − 354º = +6º and plot the effective course to Ceuta: Ref = 193º.
- Counteract the current (076º, 3 kn) with Vm = 8 kn to find Rv = 213º and subtract Ct = +6º: Ra = 207º.
Where this question comes from
- Región de Murcia · 2019 · 2ª convocatoria · PY Tipo 1 · question 33 Official paper · Official answer key
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Pending instructor review. Machine translation, not reviewed.