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Continúan navegando al rumbo verdadero= 134º y velocidad de 6 nudos y a HRB= 1320, el GPS les indica posición verdadera= 35º 57,4´N 005º 50,7´W y desde esa situación dan rumbo al Puerto de Tánger (luz de la farola del extremo del espigón del puerto), teniendo en cuenta que comienza a afectarles la corriente general de la zona con rumbo de corriente= 114º e intensidad horaria= 2 nudos y calculan el rumbo de aguja a Tánger (corrección total= - 8º).At HRB 1320 in GPS position 35º 57.4' N, 005º 50.7' W at 6 knots, you set course for Tangier port breakwater light in a current setting Rc = 114º at Ihc = 2 knots (Ct = –8º). Calculate your compass course to Tangier:
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Correct answer: b) 190º
Why it is correct
From 35º 57.4′ N, 005º 50.7′ W to Tangier breakwater light (35º 47.4′ N, 005º 48.2′ W) the effective course is Ref = 169º. Solving the current triangle with Rc = 114º, Ihc = 2 knots and Vb = 6 knots gives Rv = 182º. With Ct = −8º, the compass course is Ra = 182º − (−8º) = 190º.
Why the others are not
- a) Forgets to apply Ct = −8º to true heading Rv = 182º or applies it with the wrong sign.
- c) Forgets to apply Ct = −8º to true heading Rv = 182º or applies it with the wrong sign.
- d) Forgets to apply Ct = −8º to true heading Rv = 182º or applies it with the wrong sign.
How to work it out in the exam
- Plot the effective course to Tangier (Ref = 169º) and counteract the current (114º, 2 kn) with Vb = 6 kn ⇒ Rv = 182º.
- Convert to compass course with Ct = −8º: Ra = 182º + 8º = 190º.
Where this question comes from
- Región de Murcia · 2021 · 3ª convocatoria · PY Tipo 1 · question 36 Official paper · Official answer key
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Pending instructor review. Machine translation, not reviewed.