ASA 105 Coastal Navigation Exam V2 – Practice
Questions & Verified Answers (Latest 2026/2027) |
Chart Plotting & Navigation Problems
Section 1: Chartwork & Piloting (28 questions)
Q1. While plotting on NOAA chart 13205 you measure 4.7 nautical miles between two
way-points. The scale bar shows 1 nm = 1.85 cm. What distance in centimetres do you
lay off on your dividers?
A) 7.03 cm
B) 8.70 cm
C) 9.25 cm
D) 10.15 cm
Correct: B
Rationale: 4.7 nm × 1.85 cm/nm = 8.695 cm → round to 8.70 cm (B). Mis-scaling (A, C,
D) would introduce plotting error.
,Q2. You take a hand-bearing-compass reading of 047° on a lighthouse. The compass
card reads “5° W deviation” for that heading. Variation on the chart is 14° E. What is the
True bearing to the lighthouse?
A) 028° T
B) 038° T
C) 048° T
D) 058° T
Correct: B
Rationale: “Compass to True: add West, subtract East; add West deviation, subtract
East variation.”
047° (C) − 5° W dev + 14° E var = 038° T (B).
Q3. (Plotting) At 0930 you fix your position at Lat 40° 51.0′ N, Long 070° 29.0′ W. You
then steer 125° T at 5.5 kn. What is your DR position at 1030?
A) 40° 49.2′ N, 070° 26.0′ W
B) 40° 48.5′ N, 070° 25.3′ W
C) 40° 47.8′ N, 070° 24.5′ W
,D) 40° 47.0′ N, 070° 23.8′ W
Correct: A
Rationale: 1 h × 5.5 kn = 5.5 nm along 125° T.
dLat = 5.5 cos 125° = −3.15′ → Lat 40° 51.0′ − 3.2′ ≈ 40° 49.2′ N
dLo = 5.5 sin 125° / cos 40.85° ≈ +4.0′ → Lo 070° 29.0′ W − 4.0′ ≈ 070° 26.0′ W
Closest option: A.
Q4. (Multiple select) Which three conditions improve the accuracy of a two-bearing fix?
(Select 3.)
A) Objects 60–90° apart
B) Bearings taken simultaneously
C) Objects at similar distances from vessel
D) Large-scale chart used
E) Objects close to the vessel
Correct: A, B, D
, Rationale: Wide angle (A), simultaneity (B), and large scale (D) minimise error. Similar
distances (C) helps but is secondary; close objects (E) increase angular error.
Q5. (True/False) A position line derived from a single vertical angle sextant
measurement must be labelled with the time of observation.
Answer: TRUE
Rationale: Time labelling allows DR transfer and correlation with log entries; omitting
time invalidates subsequent dead-reckoning.
Q6. You measure a vertical angle of 2° 15′ on a lighthouse whose charted height is 45
ft. Using the vertical angle table (extract provided), the calculated distance off is closest
to:
A) 1.1 nm
B) 1.4 nm
C) 1.7 nm
D) 2.0 nm
Correct: B
Questions & Verified Answers (Latest 2026/2027) |
Chart Plotting & Navigation Problems
Section 1: Chartwork & Piloting (28 questions)
Q1. While plotting on NOAA chart 13205 you measure 4.7 nautical miles between two
way-points. The scale bar shows 1 nm = 1.85 cm. What distance in centimetres do you
lay off on your dividers?
A) 7.03 cm
B) 8.70 cm
C) 9.25 cm
D) 10.15 cm
Correct: B
Rationale: 4.7 nm × 1.85 cm/nm = 8.695 cm → round to 8.70 cm (B). Mis-scaling (A, C,
D) would introduce plotting error.
,Q2. You take a hand-bearing-compass reading of 047° on a lighthouse. The compass
card reads “5° W deviation” for that heading. Variation on the chart is 14° E. What is the
True bearing to the lighthouse?
A) 028° T
B) 038° T
C) 048° T
D) 058° T
Correct: B
Rationale: “Compass to True: add West, subtract East; add West deviation, subtract
East variation.”
047° (C) − 5° W dev + 14° E var = 038° T (B).
Q3. (Plotting) At 0930 you fix your position at Lat 40° 51.0′ N, Long 070° 29.0′ W. You
then steer 125° T at 5.5 kn. What is your DR position at 1030?
A) 40° 49.2′ N, 070° 26.0′ W
B) 40° 48.5′ N, 070° 25.3′ W
C) 40° 47.8′ N, 070° 24.5′ W
,D) 40° 47.0′ N, 070° 23.8′ W
Correct: A
Rationale: 1 h × 5.5 kn = 5.5 nm along 125° T.
dLat = 5.5 cos 125° = −3.15′ → Lat 40° 51.0′ − 3.2′ ≈ 40° 49.2′ N
dLo = 5.5 sin 125° / cos 40.85° ≈ +4.0′ → Lo 070° 29.0′ W − 4.0′ ≈ 070° 26.0′ W
Closest option: A.
Q4. (Multiple select) Which three conditions improve the accuracy of a two-bearing fix?
(Select 3.)
A) Objects 60–90° apart
B) Bearings taken simultaneously
C) Objects at similar distances from vessel
D) Large-scale chart used
E) Objects close to the vessel
Correct: A, B, D
, Rationale: Wide angle (A), simultaneity (B), and large scale (D) minimise error. Similar
distances (C) helps but is secondary; close objects (E) increase angular error.
Q5. (True/False) A position line derived from a single vertical angle sextant
measurement must be labelled with the time of observation.
Answer: TRUE
Rationale: Time labelling allows DR transfer and correlation with log entries; omitting
time invalidates subsequent dead-reckoning.
Q6. You measure a vertical angle of 2° 15′ on a lighthouse whose charted height is 45
ft. Using the vertical angle table (extract provided), the calculated distance off is closest
to:
A) 1.1 nm
B) 1.4 nm
C) 1.7 nm
D) 2.0 nm
Correct: B
