ASA 105 Coastal Navigation (Latest 2026/2027 Update) Sample
Exam Test| Questions with Approved Answers | 100% Correct
SECTION I — NAUTICAL CHARTS, PUBLICATIONS & BASIC CHARTWORK
Questions 1–50
1. What is the primary purpose of a nautical chart?
A. To display weather forecasts only
B. To provide information for marine navigation
C. To calculate boat fuel consumption only
D. To replace all navigation instruments
Answer: B
Rationale: Nautical charts provide navigational information such as
depths, hazards, aids to navigation, shoreline features, and geographic
positions.
2. Which chart is generally preferred for close-in coastal navigation?
A. Small-scale chart
B. Large-scale chart
C. World plotting chart
D. Climatic chart
Answer: B
Rationale: A large-scale chart covers a smaller geographic area but
provides greater detail, making it more useful for close navigation.
,3. Which chart scale provides the greatest detail?
A. 1:500,000
B. 1:250,000
C. 1:100,000
D. 1:20,000
Answer: D
Rationale: The smaller the denominator, the larger the scale and the
greater the chart detail.
4. A chart scale of 1:80,000 means:
A. One chart unit represents 80,000 units on Earth.
B. 80,000 chart units equal one Earth unit.
C. One nautical mile equals 80,000 nautical miles.
D. One inch always equals exactly one mile.
Answer: A
Rationale: The scale ratio means one unit measured on the chart
represents 80,000 of the same units on the Earth's surface.
5. Why should distance on a Mercator chart normally be measured
using the latitude scale?
A. Longitude scales are used only for depth
B. One minute of latitude corresponds to approximately one nautical
mile
,C. Latitude scales never change
D. Longitude is unrelated to distance
Answer: B
Rationale: On a nautical chart, distance is commonly measured from
the latitude scale because one minute of latitude represents
approximately one nautical mile.
6. What is the principal navigational advantage of the Mercator
projection?
A. Great circles appear as straight lines
B. Rhumb lines appear as straight lines
C. All distances are exact everywhere
D. The poles occupy no space
Answer: B
Rationale: A constant-bearing rhumb line plots as a straight line on a
Mercator chart, making traditional course plotting convenient.
7. A rhumb line is:
A. A route crossing every meridian at a constant angle
B. Always the shortest route on Earth
C. A line of equal depth
D. A line of equal latitude only
Answer: A
Rationale: A rhumb line maintains a constant true bearing.
, 8. Which projection is commonly associated with great-circle routes?
A. Mercator
B. Gnomonic
C. Lambert only
D. Cylindrical equal-area
Answer: B
Rationale: Great circles appear as straight or nearly straight lines on a
gnomonic projection, making it useful for great-circle planning.
9. What does a chart's compass rose provide?
A. Current speed only
B. Directional reference, including true and often magnetic information
C. Depth information
D. Weather forecasts
Answer: B
Rationale: The compass rose is used to measure and convert directions
on the chart.
10. Which direction is represented by 000° or 360°?
A. East
B. South
C. West
D. North
Exam Test| Questions with Approved Answers | 100% Correct
SECTION I — NAUTICAL CHARTS, PUBLICATIONS & BASIC CHARTWORK
Questions 1–50
1. What is the primary purpose of a nautical chart?
A. To display weather forecasts only
B. To provide information for marine navigation
C. To calculate boat fuel consumption only
D. To replace all navigation instruments
Answer: B
Rationale: Nautical charts provide navigational information such as
depths, hazards, aids to navigation, shoreline features, and geographic
positions.
2. Which chart is generally preferred for close-in coastal navigation?
A. Small-scale chart
B. Large-scale chart
C. World plotting chart
D. Climatic chart
Answer: B
Rationale: A large-scale chart covers a smaller geographic area but
provides greater detail, making it more useful for close navigation.
,3. Which chart scale provides the greatest detail?
A. 1:500,000
B. 1:250,000
C. 1:100,000
D. 1:20,000
Answer: D
Rationale: The smaller the denominator, the larger the scale and the
greater the chart detail.
4. A chart scale of 1:80,000 means:
A. One chart unit represents 80,000 units on Earth.
B. 80,000 chart units equal one Earth unit.
C. One nautical mile equals 80,000 nautical miles.
D. One inch always equals exactly one mile.
Answer: A
Rationale: The scale ratio means one unit measured on the chart
represents 80,000 of the same units on the Earth's surface.
5. Why should distance on a Mercator chart normally be measured
using the latitude scale?
A. Longitude scales are used only for depth
B. One minute of latitude corresponds to approximately one nautical
mile
,C. Latitude scales never change
D. Longitude is unrelated to distance
Answer: B
Rationale: On a nautical chart, distance is commonly measured from
the latitude scale because one minute of latitude represents
approximately one nautical mile.
6. What is the principal navigational advantage of the Mercator
projection?
A. Great circles appear as straight lines
B. Rhumb lines appear as straight lines
C. All distances are exact everywhere
D. The poles occupy no space
Answer: B
Rationale: A constant-bearing rhumb line plots as a straight line on a
Mercator chart, making traditional course plotting convenient.
7. A rhumb line is:
A. A route crossing every meridian at a constant angle
B. Always the shortest route on Earth
C. A line of equal depth
D. A line of equal latitude only
Answer: A
Rationale: A rhumb line maintains a constant true bearing.
, 8. Which projection is commonly associated with great-circle routes?
A. Mercator
B. Gnomonic
C. Lambert only
D. Cylindrical equal-area
Answer: B
Rationale: Great circles appear as straight or nearly straight lines on a
gnomonic projection, making it useful for great-circle planning.
9. What does a chart's compass rose provide?
A. Current speed only
B. Directional reference, including true and often magnetic information
C. Depth information
D. Weather forecasts
Answer: B
Rationale: The compass rose is used to measure and convert directions
on the chart.
10. Which direction is represented by 000° or 360°?
A. East
B. South
C. West
D. North
