ASA 105 Practice Exam Questions With
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. What is the primary purpose of a nautical chart?
A. To show weather patterns
B. To display underwater marine life
C. To provide detailed navigational information for safe passage
D. To show political boundaries
Correct Answer: C
Rationale: Nautical charts are designed to provide critical navigation
information such as depths, hazards, aids to navigation, and shoreline
details to ensure safe vessel passage.
2. What does “depth soundings” on a chart indicate?
A. Air temperature above water
B. Water depth at chart datum
C. Boat speed in knots
D. Distance between buoys
Correct Answer: B
,Rationale: Depth soundings show the depth of water relative to chart
datum, helping navigators avoid shallow areas.
3. What is the function of a compass rose on a chart?
A. Shows tide heights
B. Displays magnetic and true directions
C. Indicates boat speed
D. Marks fishing zones
Correct Answer: B
Rationale: The compass rose provides both true and magnetic
bearings for navigation and course plotting.
4. What is variation in navigation?
A. Change in wind speed
B. Difference between true north and magnetic north
C. Difference in boat speed
D. Tide height change
Correct Answer: B
Rationale: Variation is the angular difference between true north
(geographic) and magnetic north due to Earth's magnetic field.
5. What is deviation?
A. Wind direction change
B. Error caused by currents
,C. Magnetic error caused by onboard metal/equipment
D. Difference in tide levels
Correct Answer: C
Rationale: Deviation is caused by magnetic interference from the
vessel itself, affecting compass readings.
6. What is a Dead Reckoning (DR) position?
A. Exact GPS position
B. Estimated position based on course and speed only
C. Position based on radar
D. Anchoring location
Correct Answer: B
Rationale: DR position is calculated using known course, speed, and
time without accounting for external influences like wind or current.
7. What is a fix in navigation?
A. Estimated position only
B. Position determined using at least two lines of position
C. Compass error
D. Engine setting
Correct Answer: B
Rationale: A fix is a precise position determined by intersecting two or
more lines of position.
, 8. What does a nautical mile represent?
A. 1 km
B. 1.15 miles
C. 1 minute of latitude
D. 1000 meters exactly
Correct Answer: C
Rationale: A nautical mile equals one minute of latitude,
approximately 1.852 km.
9. What is the standard unit of speed at sea?
A. Miles per hour
B. Kilometers per hour
C. Knots
D. Feet per second
Correct Answer: C
Rationale: Nautical speed is measured in knots, where 1 knot equals 1
nautical mile per hour.
10. What does a “chart datum” refer to?
A. Highest tide level
B. Reference level for depth measurements
C. Boat launch point
D. Weather baseline
Correct Answer: B
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of a nautical chart?
A. To show weather patterns
B. To display underwater marine life
C. To provide detailed navigational information for safe passage
D. To show political boundaries
Correct Answer: C
Rationale: Nautical charts are designed to provide critical navigation
information such as depths, hazards, aids to navigation, and shoreline
details to ensure safe vessel passage.
2. What does “depth soundings” on a chart indicate?
A. Air temperature above water
B. Water depth at chart datum
C. Boat speed in knots
D. Distance between buoys
Correct Answer: B
,Rationale: Depth soundings show the depth of water relative to chart
datum, helping navigators avoid shallow areas.
3. What is the function of a compass rose on a chart?
A. Shows tide heights
B. Displays magnetic and true directions
C. Indicates boat speed
D. Marks fishing zones
Correct Answer: B
Rationale: The compass rose provides both true and magnetic
bearings for navigation and course plotting.
4. What is variation in navigation?
A. Change in wind speed
B. Difference between true north and magnetic north
C. Difference in boat speed
D. Tide height change
Correct Answer: B
Rationale: Variation is the angular difference between true north
(geographic) and magnetic north due to Earth's magnetic field.
5. What is deviation?
A. Wind direction change
B. Error caused by currents
,C. Magnetic error caused by onboard metal/equipment
D. Difference in tide levels
Correct Answer: C
Rationale: Deviation is caused by magnetic interference from the
vessel itself, affecting compass readings.
6. What is a Dead Reckoning (DR) position?
A. Exact GPS position
B. Estimated position based on course and speed only
C. Position based on radar
D. Anchoring location
Correct Answer: B
Rationale: DR position is calculated using known course, speed, and
time without accounting for external influences like wind or current.
7. What is a fix in navigation?
A. Estimated position only
B. Position determined using at least two lines of position
C. Compass error
D. Engine setting
Correct Answer: B
Rationale: A fix is a precise position determined by intersecting two or
more lines of position.
, 8. What does a nautical mile represent?
A. 1 km
B. 1.15 miles
C. 1 minute of latitude
D. 1000 meters exactly
Correct Answer: C
Rationale: A nautical mile equals one minute of latitude,
approximately 1.852 km.
9. What is the standard unit of speed at sea?
A. Miles per hour
B. Kilometers per hour
C. Knots
D. Feet per second
Correct Answer: C
Rationale: Nautical speed is measured in knots, where 1 knot equals 1
nautical mile per hour.
10. What does a “chart datum” refer to?
A. Highest tide level
B. Reference level for depth measurements
C. Boat launch point
D. Weather baseline
Correct Answer: B
