Hover or tap underlined Spanish terms to see their translation and exam tip.
A HRB = 19-00 en situación l = 36º-01,0’ N L = 005º-20,5’ W se da rumbo para pasar a 2,5 millas del Faro de isla Tarifa, dm = 3º NW, Desvío = 7º NE. Calcular el Ra.At 19:00 ship’s time in position l = 36º 01.0' N, L = 005º 20.5' W, you set course to pass 2.5 miles off Isla de Tarifa lighthouse (dm = 3º NW, Deviation = 7º NE). Calculate the compass course (Ra):
Show the answer
Correct answer: c) Ra = 250º
Why it is correct
From 36º 01.0′ N, 005º 20.5′ W, the tangent to a 2.5-mile arc south of Isla de Tarifa gives true course Rv = 254º. With Ct = −3º + 7º = +4º, the compass course is Ra = Rv − Ct = 254º − 4º = 250º.
Why the others are not
- a) Does not subtract Ct = +4º from the true course tangent to the 2.5-mile arc off Isla de Tarifa (254º).
- b) Does not subtract Ct = +4º from the true course tangent to the 2.5-mile arc off Isla de Tarifa (254º).
- d) Does not subtract Ct = +4º from the true course tangent to the 2.5-mile arc off Isla de Tarifa (254º).
How to work it out in the exam
- Draw from 36º 01.0′ N, 005º 20.5′ W the tangent to the 2.5-mile arc off Isla de Tarifa: Rv = 254º.
- With Ct = −3º + 7º = +4º, compute Ra = 254º − 4º = 250º.
Where this question comes from
- Junta de Andalucía · 2015 · 2ª convocatoria · PER Modelo A · question 45 Official paper · Official answer key
- Junta de Andalucía · 2015 · 2ª convocatoria · PER Modelo B · question 42 Official paper · Official answer key
Try it: Navigation calculations
Pending instructor review. Machine translation, not reviewed.