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A HRB= 1524 el GPS les da situación verdadera= 36º 00,6'N – 006º 05,1’W y desde esta posición dan rumbo al Puerto de Barbate (luz roja extremo espigón) con velocidad de 8 nudos. La corriente general de la zona (rumbo corriente= 112º e intensidad horaria de la corriente=2 nudos) les afectará en todo el recorrido y teniendo en cuenta estos datos, calculan la HRB de llegada a Barbate:At HRB 1524 in GPS position 36º 00.6' N – 006º 05.1' W, you set course for Barbate port (red breakwater light) at 8 knots in a current setting Rc = 112º at Ihc = 2 knots. Calculate your HRB of arrival at Barbate:
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Correct answer: c) 1657
Why it is correct
From 36º 00.6′ N, 006º 05.1′ W to Barbate red breakwater light (36º 11.3′ N, 005º 55.3′ W) is 13.4 miles along effective course Ref = 037º. Solving the current triangle (Rc = 112º, Ihc = 2 knots, Vb = 8 knots) gives effective speed Vef = 8.65 knots; time is 13.4 / 8.65 = 1.55 h (1h 33m) ⇒ HRB = 15:24 + 1h 33m = 1657.
Why the others are not
- a) Does not compute the time using effective speed Vef = 8.65 knots over the 13.4 miles to Barbate.
- b) Does not compute the time using effective speed Vef = 8.65 knots over the 13.4 miles to Barbate.
- d) Does not compute the time using effective speed Vef = 8.65 knots over the 13.4 miles to Barbate.
How to work it out in the exam
- Measure the effective course (037º) and distance (13.4 miles) from the GPS position to Barbate.
- Solve the triangle with Rc = 112º (2 kn) and Vb = 8 kn: Vef = 8.65 kn ⇒ t = 1h 33m ⇒ arrival at 1657.
Where this question comes from
- Región de Murcia · 2021 · 2ª convocatoria · PY Tipo 1 · question 37 Official paper · Official answer key
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Pending instructor review. Machine translation, not reviewed.