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A HRB = 16h 15m del 22 de marzo nos encontramos en situación 36º 00′ N, 006º 00′ W. Navegamos a 4 nudos al rumbo de aguja 323°. Calcular la situación de estima a HRB = 18h 30m. Declinación magnética = 2º NW y desvío de la aguja = –6° (menos).At ship’s clock 16h 15m on 22 March we are at 36º 00′ N, 006º 00′ W. We sail at 4 knots on compass course 323°. Calculate the dead reckoning position at 18h 30m. Magnetic variation = 2º NW and compass deviation = –6° (minus).
Show the answer
Correct answer: b) 36º 06.4' N; 006º 08.0' W
Why it is correct
Total correction = −2º − 6º = −8º, so true course = 323º − 8º = 315º. 2.25 h at 4 knots is 9 miles: 6.4′ north and 6.4 miles west, which is 7.9′ of longitude.
Why the others are not
- a) The working gives 36º 06,4′ N, 006º 07,9′ W, and this option does not match.
- c) The working gives 36º 06,4′ N, 006º 07,9′ W, and this option does not match.
- d) The working gives 36º 06,4′ N, 006º 07,9′ W, and this option does not match.
How to work it out in the exam
- Find the true course: true = compass + total correction.
- Distance = speed × time.
- Draw the course on the chart, measure the distance and read the position.
Where this question comes from
- Junta de Andalucía · 2025 · 1ª convocatoria · PER Modelo A · question 44 Official paper · Official answer key
- Junta de Andalucía · 2025 · 1ª convocatoria · PER Modelo B · question 44 Official paper · Official answer key
Try it: Navigation calculations
Pending instructor review. Machine translation, not reviewed.