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Un yate se encuentra en un punto situado a 7 millas al Nv del faro de Punta Cires, y se pone a navegar al Ra = S65W, desvío = 8º NW, dm =4º NW, velocidad 12 nudos. ¿En qué posición se encontrará después de navegar 1 h. y 15 min?A yacht located 7 miles due North true of Punta Cires lighthouse steers compass course Ra = S65W (deviation 8º NW, variation 4º NW) at 12 knots. What is its position after steaming for 1 hour 15 minutes?

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Correct answer: d) l = 35º 52.6' N L = 005º 43.5' W

Why it is correct

The point 7 miles due North of Punta Cires (35º 54.7′ N, 005º 28.8′ W) is 36º 01.7′ N, 005º 28.8′ W. With Ra = S65W = 245º and Ct = −4º − 8º = −12º, true course is Rv = 245º − 12º = 233º. In 1h 15m (1.25 h) at 12 knots the yacht runs 15 miles along 233º, reaching l = 35º 52.6′ N, L = 005º 43.5′ W.

Why the others are not

  • a) Does not lay off 15 miles along true course Rv = 233º from 7′ N of Punta Cires.
  • b) Does not lay off 15 miles along true course Rv = 233º from 7′ N of Punta Cires.
  • c) Does not lay off 15 miles along true course Rv = 233º from 7′ N of Punta Cires.

How to work it out in the exam

  1. Plot the start 7′ N of Punta Cires (36º 01.7′ N, 005º 28.8′ W) and compute Rv = 245º − 12º = 233º.
  2. Measure 15 miles (1.25 h at 12 knots) along 233º: 35º 52.6′ N, 005º 43.5′ W.

Where this question comes from

Try it: Navigation calculations

Pending instructor review. Machine translation, not reviewed.