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Determinar el rumbo de aguja (Ra) para navegar desde la luz roja del dique del puerto de Algeciras hasta el faro de Punta Almina con un viento de levante que abate 4°. Desvío de la aguja para dicho rumbo = -5° y declinación magnética la obtenida en la carta de enseñanza del Estrecho de Gibraltar para el año 2020.Determine the compass course (Ra) to sail from Algeciras port breakwater red light to Punta Almina lighthouse with an easterly wind causing 4° leeway (deviation –5° and chart variation for the year 2020):
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Correct answer: a) Ra = 156°.
Why it is correct
From Algeciras breakwater red light (36º 07.9′ N, 005º 26.0′ W) to Punta Almina lighthouse (35º 54.0′ N, 005º 16.5′ W) the charted surface course is Rs = 154º. With an easterly wind on the port side (+4º starboard leeway), steer 4º to port: Rv = 154º − 4º = 150º. In 2020 charted variation is dm ≈ −1º; with deviation −5º, Ct = −6º and Ra = 150º + 6º = 156º.
Why the others are not
- b) Does not offset the easterly leeway to port (−4º) or fails to add the 6º negative compass error.
- c) Does not offset the easterly leeway to port (−4º) or fails to add the 6º negative compass error.
- d) Does not offset the easterly leeway to port (−4º) or fails to add the 6º negative compass error.
How to work it out in the exam
- Measure on the chart the direct course from Algeciras red light to Punta Almina: Rs = 154º.
- Subtract 4º starboard leeway (Rv = 150º) and apply Ct = −6º: Ra = 156º.
Where this question comes from
- Ministerio de Transportes (Madrid) · 2020 · Convocatoria de diciembre · PY Test 1 · question 31 Official paper · Official answer key
Try it: Navigation calculations
Pending instructor review. Machine translation, not reviewed.