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A las 18h 20m del 15 de noviembre de 2025, nos encontramos en situación verdadera 36º 00,0' N, 005º 50,0' W. Navegamos a 6 nudos al rumbo de aguja 311°. Calcular la situación de estima a las 20h 35m, sabiendo que el desvío de la aguja es –6° (menos) y que la declinación magnética es 5º NW.At 18h 20m on 15 November 2025 we are at true position 36º 00.0' N, 005º 50.0' W. We sail at 6 knots on compass course 311°. Calculate the dead reckoning position at 20h 35m, given that compass deviation is –6° (minus) and magnetic variation 5º NW.
Show the answer
Correct answer: a) 36º 06.8' N; 006º 04.4' W
Why it is correct
Total correction = −5º − 6º = −11º, so true course = 311º − 11º = 300º. 2.25 h at 6 knots is 13.5 miles: 6.8′ north and 11.7 miles west, which is 14.5′ of longitude.
Why the others are not
- b) The working gives 36º 06,7′ N, 006º 04,5′ W, and this option does not match.
- c) The working gives 36º 06,7′ N, 006º 04,5′ W, and this option does not match.
- d) The working gives 36º 06,7′ N, 006º 04,5′ 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 · 3ª convocatoria · PER Modelo A · question 43 Official paper · Official answer key
- Junta de Andalucía · 2025 · 3ª convocatoria · PER Modelo B · question 45 Official paper · Official answer key
Try it: Navigation calculations
Pending instructor review. Machine translation, not reviewed.