200-Ton Master Navigation General Practice Questions

Sample questions — Navigation General

Drawn from the same bank used on USCG licensing exams. Correct answers and explanations are shown — read every explanation, even for questions you get right.

1. 1. A vessel departs a known position at 0800 on course 090°T at 12 knots. What is the DR position at 1100?

   • A.36 nautical miles east of the departure point✓
   • B.24 nautical miles east of the departure point
   • C.48 nautical miles east of the departure point
   • D.36 nautical miles west of the departure point

   Why: Time elapsed = 1100 - 0800 = 3 hours. Distance = Speed × Time = 12 × 3 = 36 nm. Course 090°T is due east, so the DR position is 36 nm east of departure.

2. 2. Which geometric arrangement of three simultaneous LOPs gives the most reliable three-bearing fix?

   • A.All three bearings within 30° of each other
   • B.Bearings approximately 60° apart
   • C.Two parallel bearings and one crossing them at 90°
   • D.Bearings approximately 120° apart✓

   Why: Three LOPs approximately 120° apart (cutting at 60° angles to each other) produce the best geometry, minimizing the cocked hat triangle error. LOPs that are nearly parallel greatly amplify position errors.

3. 3. Using the Rule of Twelfths, how much of the total tidal range occurs during the SECOND hour of a rising tide?

   • A.1/12 of the range
   • B.2/12 of the range✓
   • C.3/12 of the range
   • D.4/12 of the range

   Why: The Rule of Twelfths states that tidal rise/fall is not uniform. The distribution per hour is: 1st hour = 1/12, 2nd hour = 2/12, 3rd hour = 3/12, 4th hour = 3/12, 5th hour = 2/12, 6th hour = 1/12. So the 2nd hour = 2/12 of the range.

4. 4. A vessel is steering 180°T at 10 knots through the water. A current sets 090°T at 3 knots. Using the current triangle, the SMG is approximately:

   • A.10.0 knots
   • B.13.0 knots
   • C.10.4 knots✓
   • D.7.0 knots

   Why: The vessel moves south at 10 kts; current pushes east at 3 kts. These vectors are perpendicular. SMG = √(10² + 3²) = √(100 + 9) = √109 ≈ 10.4 knots. The CMG will be slightly east of south.

5. 5. A running fix is generally considered less reliable than a fix from simultaneous bearings because:

   • A.Only one lighthouse can be used for a running fix
   • B.The accuracy depends on the precision of the course and distance run between observations✓
   • C.Running fixes cannot be plotted on Mercator charts
   • D.A running fix always results in a larger cocked hat

   Why: A running fix requires advancing an earlier LOP, which depends on knowing the exact course made good and distance run between bearings. Any errors in CMG (from current, leeway, or compass error) or distance run will introduce error into the advanced LOP and the resulting fix.

6. 6. Lateral buoy numbers in U.S. waters increase in which direction?

   • A.From sea toward the head of navigation✓
   • B.From the head of navigation toward the sea
   • C.From south to north regardless of channel direction
   • D.From east to west along the coastline

   Why: Buoy numbers increase from seaward toward the head of navigation (harbor, river mouth, etc.). Even numbers are on the right (starboard/red) side going in.

7. 7. A FIXED light (F) is described as:

   • A.A light that shows a single flash at regular intervals
   • B.A continuous, steady light with no interruptions✓
   • C.A light that is on longer than it is off
   • D.A light that alternates between two colors at equal intervals

   Why: A Fixed (F) light is a continuous, uninterrupted light — it does not flash or occult. It remains on at constant intensity.

8. 8. Deviation is caused by:

   • A.The geographic location of the vessel
   • B.Magnetic materials and electrical currents aboard the vessel itself✓
   • C.Solar and lunar gravitational pull on the compass needle
   • D.The difference between geographic and magnetic poles

   Why: Deviation is the error in the magnetic compass caused by the vessel's own magnetic field — permanent magnetism in the hull, engines, electrical wiring, and cargo. It changes with the ship's heading.

9. 9. Variation: 20° W, Deviation: 4° W. A compass course of 350° converts to what true course?

   • A.326°✓
   • B.334°
   • C.366° (006°)
   • D.374° (014°)

   Why: Compass→True (correcting): add East, subtract West. Magnetic = 350° − 4°W = 346°. True = 346° − 20°W = 326°. Answer: 326°T.

10. 10. While entering a harbor, you observe a red-and-green horizontally banded buoy with the topmost band GREEN. You should treat it as:

    • A.A red (starboard-hand) aid — preferred channel is to starboard of the buoy
    • B.A green (port-hand) aid — preferred channel is to port of the buoy✓
    • C.A safe water mark — pass on either side
    • D.An isolated danger mark — give it wide berth on all sides

    Why: Under IALA Region B (33 CFR 62.25), a red-and-green banded preferred-channel (junction) mark with the TOPMOST band GREEN (GRG, light Fl(2+1)G) serves as a port-hand (green) aid for vessels following the preferred channel in the conventional direction. You keep it to PORT to stay in the preferred channel, so the preferred channel lies to the port side of the buoy (pass it on your starboard side only if you intend to take the lesser, secondary channel).

11. 11. On a nautical chart with a scale of 1:80,000, a measured distance of 2 inches on the chart represents approximately how many nautical miles?

    • A.2.19 nautical miles✓
    • B.4.38 nautical miles
    • C.1.09 nautical miles
    • D.8.76 nautical miles

    Why: At 1:80,000, one inch equals 80,000 inches on the earth. There are 72,913 inches in one nautical mile, so 2 inches equals 160,000 ÷ 72,913 ≈ 2.19 nautical miles.

12. 12. The abbreviation 'PA' appearing next to a charted feature on a nautical chart means:

    • A.Position approximate✓
    • B.Prohibited anchorage
    • C.Partial above-water
    • D.Private aid

    Why: Per Chart No. 1, 'PA' stands for 'Position Approximate,' indicating the charted position of the feature is not precisely known and mariners should exercise caution.

13. 13. One degree of latitude on a nautical chart is equal to:

    • A.60 nautical miles✓
    • B.60 statute miles
    • C.69 nautical miles
    • D.One nautical mile

    Why: By definition, one minute of latitude equals one nautical mile; therefore one degree of latitude (60 minutes) equals exactly 60 nautical miles, which is the basis for using the latitude scale to measure nautical miles.

14. 14. Using the memory aid 'Can Dead Men Vote Twice At Elections,' the correct order for converting a compass heading to a true heading is:

    • A.Compass → Deviation → Magnetic → Variation → True✓
    • B.Compass → Variation → Magnetic → Deviation → True
    • C.True → Deviation → Magnetic → Variation → Compass
    • D.Compass → Magnetic → Deviation → Variation → True

    Why: The mnemonic 'Can Dead Men Vote Twice At Elections' represents Compass, Deviation, Magnetic, Variation, True — the order used when converting from compass to true. Add easterly errors, subtract westerly errors (ADDEAST rule).

15. 15. On a nautical chart, variation is shown in the:

    • A.Compass rose printed on the chart, as degrees and direction✓
    • B.Title block in the upper right corner of the chart
    • C.Caution notes along the chart borders
    • D.Depth contour legend at the bottom of the chart

    Why: Nautical charts printed by NOAA show magnetic variation on the compass rose, which includes both the true (outer) and magnetic (inner) roses. The amount of variation and its annual rate of change are printed inside the compass rose.

16. 16. A depth contour line on a chart can be used as a line of position when:

    • A.The echo sounder shows a depth that corresponds to a charted depth contour in the area✓
    • B.The vessel is in shallow water where GPS is unreliable
    • C.The tidal range is less than 1 foot at the time of observation
    • D.Two contour lines of different depths are available simultaneously

    Why: A depth sounding matched to a charted depth contour gives a circular (or curvilinear) line of position — the vessel must be somewhere along that contour. This technique is especially useful in poor visibility when cross-bearing fixes are unavailable.

17. 17. A chart symbol showing an anchor with a circle around it indicates:

    • A.A prohibited anchorage
    • B.A recommended anchorage✓
    • C.A fish haven obstruction
    • D.An abandoned anchor wreck

    Why: In Chart No. 1, an anchor with a surrounding circle denotes a recommended or designated anchorage. A prohibited anchorage is typically shown with the same anchor symbol but with a magenta circle and cross (prohibition symbol) or magenta text. Fish havens use an obstruction symbol with foul-ground notation.

18. 18. To reduce sea clutter on a radar display, the operator should adjust:

    • A.The FTC (Fast Time Constant) or rain clutter control
    • B.The STC (Sensitivity Time Control) or sea clutter control✓
    • C.The antenna rotation rate
    • D.The pulse repetition frequency (PRF)

    Why: Sea clutter is suppressed using the STC (Sensitivity Time Control) control, which reduces receiver sensitivity for the short ranges where wave returns appear. FTC (Fast Time Constant) — also called the rain or differentiation control — reduces rain clutter by differentiating the signal to enhance target edges. Overusing either control can eliminate real targets.

19. 19. A major limitation of ARPA that the watchkeeper must understand is:

    • A.ARPA cannot display targets at ranges greater than 12 miles
    • B.ARPA cannot detect targets that are stationary
    • C.ARPA tracking accuracy depends on the quality of the radar echo; small or poor-reflecting targets may be tracked inaccurately or lost✓
    • D.ARPA requires manual input of own ship's speed and course to compute target vectors

    Why: ARPA tracking relies on the consistency and quality of the radar echo. Targets with poor radar cross-section, those in heavy clutter, or those undergoing evasive maneuvers may be tracked inaccurately or dropped. The watchkeeper must never rely solely on ARPA alarms and must verify CPA data against manual observation. Modern ARPA uses own ship sensors (GPS/gyro/log) for motion input, not manual entry.

20. 20. Under what circumstance should a vessel's AIS transmitter be switched off or its transmission suspended?

    • A.Whenever anchored in a designated anchorage
    • B.In areas of heavy vessel traffic to prevent display clutter
    • C.When the master determines that continuous AIS broadcasting would compromise the vessel's security✓
    • D.Automatically when vessel speed drops below 2 knots

    Why: IMO guidelines allow the master to switch off AIS transmissions when, in professional judgment, continuous transmitting would compromise the vessel's safety or security (e.g., when transiting piracy-prone areas). Anchoring alone does not justify disabling AIS, and AIS does not have an automatic speed-based shutoff. VTS or flag-state authority may also direct suspension.

Frequently asked questions

Is Navigation General on the 200-Ton Master exam?

Yes — Navigation General is one of the tested modules on the 200-Ton Master licensing exam. Candidates must score 70% on each module to pass.

How many Navigation General questions are on the 200-Ton Master exam?

The USCG draws from a bank of 213 Navigation General questions across all exams. The exact number on any single sitting varies, but Rules of the Road is typically the largest module and has the highest passing threshold (90%).

What is the best way to study Navigation General for the 200-Ton Master exam?

Work through the practice questions in this bank until you can answer them consistently above the passing threshold. Review every explanation — understanding why the wrong answers are wrong matters more than memorizing facts.