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A HRB= 06:00, navegando al Ra (rumbo de aguja) = 132º con Velocidad = 12 nudos, sin viento ni corriente, se toma azimut de aguja a la estrella Polar= 007º. A HRB= 06:10, se toma primera demora de aguja al faro de Trafalgar= 037º. A HRB= 06:30, se toma segunda demora de aguja al faro de Trafalgar= 337º. Indique el Rumbo verdadero al que se navega:At 06:00 ship’s time, steering compass course Ra = 132º at 12 knots with no wind or current, you observe a compass azimuth of Polaris = 007º (and later bearings of Trafalgar at 06:10 and 06:30). What true course are you steering?
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Correct answer: b) 125º
Why it is correct
Taking Polaris at true north (Zv = 000º), total compass error is Ct = Zv − Za = 000º − 007º = −7º. Therefore the true course is Rv = Ra + Ct = 132º − 7º = 125º.
Why the others are not
- a) Does not apply Ct = 000º − Za = −7º to compass course Ra = 132º.
- c) Does not apply Ct = 000º − Za = −7º to compass course Ra = 132º.
- d) Does not apply Ct = 000º − Za = −7º to compass course Ra = 132º.
How to work it out in the exam
- Find total compass error from Polaris: Ct = 000º − 007º = −7º.
- Add Ct to the compass course: Rv = 132º + (−7º) = 125º.
Where this question comes from
- Región de Murcia · 2025 · 2ª convocatoria · PY Tipo 1 · question 33 Official paper · Official answer key
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Pending instructor review. Machine translation, not reviewed.