Hover or tap underlined Spanish terms to see their translation and exam tip.
Navegando obtenemos una demora de aguja al faro de Cabo Trafagar de 315°, simultáneamente tomamos otra demora de aguja al faro de la Isla de Tarifa de 070°. El desvío de la aguja es 1° (+) y la declinación magnética 1° W. Indicar cuál es nuestra situación más aproximada.While underway you simultaneously take compass bearings Da = 315° to Cape Trafalgar lighthouse and Da = 070° to Isla de Tarifa lighthouse (deviation +1°, variation 1° W). Find your position:
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Correct answer: b) l = 35° 57.4' N; L = 005° 45.3' W.
Why it is correct
With variation −1º and deviation +1º, total compass error is Ct = 0º, so true bearings equal compass bearings: Dv(Trafalgar) = 315º and Dv(Tarifa) = 070º. Their charted intersection is l = 35º 57.4′ N, L = 005º 45.3′ W.
Why the others are not
- a) Does not match the intersection of Dv(Trafalgar) = 315º and Dv(Tarifa) = 070º (or has wrong longitude degree 006º).
- c) Does not match the intersection of Dv(Trafalgar) = 315º and Dv(Tarifa) = 070º (or has wrong longitude degree 006º).
- d) Does not match the intersection of Dv(Trafalgar) = 315º and Dv(Tarifa) = 070º (or has wrong longitude degree 006º).
How to work it out in the exam
- With Ct = −1º + 1º = 0º, use Dv(Trafalgar) = 315º and Dv(Tarifa) = 070º.
- Plot their reciprocals (135º from Trafalgar and 250º from Tarifa): 35º 57.4′ N, 005º 45.3′ W.
Where this question comes from
- Ministerio de Transportes (Madrid) · 2023 · Convocatoria de junio · PER Test 2 · question 43 Official paper · Official answer key
- Ministerio de Transportes (Madrid) · 2023 · Convocatoria de junio · PER Test 4 · question 42 Official paper · Official answer key
Try it: Navigation calculations
Pending instructor review. Machine translation, not reviewed.