Hover or tap underlined Spanish terms to see their translation and exam tip.
Al cruzar la enfilación de los faros de C.º Roche y C.º Trafalgar, la marcamos en demora de aguja 316º. Dec. magnética = 2º W. Calcular la corrección total.While crossing the leading line of Cabo Roche and Cape Trafalgar lighthouses, you observe it at a compass bearing of 316º (variation 2º W). Calculate the total compass error:
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Correct answer: a) +7º (plus)
Why it is correct
On the leading line of Cape Trafalgar and Cabo Roche lighthouses (looking NW from southeast of Trafalgar), the charted true bearing is Dv = 323º. Subtracting the compass bearing Da = 316º directly gives total compass error Ct = 323º − 316º = +7º.
Why the others are not
- b) Subtracts or adds magnetic variation to Ct when Dv − Da already gives total compass error.
- c) Subtracts or adds magnetic variation to Ct when Dv − Da already gives total compass error.
- d) Subtracts or adds magnetic variation to Ct when Dv − Da already gives total compass error.
How to work it out in the exam
- Measure on the chart the true bearing of the Trafalgar–Roche alignment: Dv = 323º.
- Subtract the compass bearing: Ct = 323º − 316º = +7º.
Where this question comes from
- Junta de Andalucía · 2023 · 2ª convocatoria · PY Módulo de navegación · question 13 Official paper · Official answer key
Try it: Navigation calculations
Pending instructor review. Machine translation, not reviewed.