10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
These 10 free USCG-CM-UNL questions are organized by exam domain, so you can see how each part of the National Chief Mate Unlimited OC or NC blueprint is tested. Reveal the answer and explanation under each question.
In dense fog under the International Rules, a cargo ship detects another vessel by radar alone, 30° on the port bow. Systematic plotting establishes a risk of collision; this is not an overtaking situation. The officer of the watch says, "The contact is to port, so we are stand-on." Which assessment is correct?
Correct answer: C - No stand-on status arises here; your ship must take avoiding action in ample time.
Two power-driven ships are crossing in clear visibility under the International Rules. The other ship is on your port side and has made an early, substantial alteration to pass well astern. Its bearing is opening, repeated plots confirm a safe passing distance, and no other hazard requires you to maneuver. What is your proper response at this stage?
Correct answer: D - Maintain course and speed while continuing to monitor the passage.
While making headway close to a channel’s starboard bank, a loaded ship begins sheering to port and its stern closes the bank. The rudder is responding correctly, and the effect strengthens as bank clearance decreases. Which hydrodynamic mechanism accounts for both movements?
Correct answer: B - Bow cushion pushes the bow off while bank suction draws the stern in.
A shipboard crane has lifted a heavy unit clear of the quay and slewed it over the hatch. With the crane head fixed, the operator lowers the freely suspended unit toward the tank top without landing it. Neglect changes in the weight distribution of the hoisting gear. What happens to the ship’s effective KG during this lowering?
Correct answer: A - It remains unchanged while the unit is freely suspended.
Remote sampling from a sealed coal hold shows a sustained rise in carbon monoxide and cargo temperature, while methane remains undetected. A deck officer proposes forced ventilation to clear the accumulated gas. Which response addresses the developing cargo hazard?
Correct answer: D - Minimize air ingress because added oxygen can intensify self-heating.
Fixed CO₂ has been released into a machinery space after everyone was accounted for, fuel supplies were isolated, and ventilation was secured. Only a few minutes have passed since discharge; external temperatures are falling, but extinction has not been confirmed. A team requests ventilation so it can enter and inspect. Which instruction should the chief mate give?
Correct answer: A - Keep the space sealed; continue boundary monitoring and authorized cooling.
A departure condition has displacement 18,000 metric tonnes, KM 9.20 m, and KG 8.15 m before free-surface correction. The combined free-surface moment of all slack tanks is 5,400 tonne-metres. The vessel’s approved loading information requires a corrected GM of at least 0.60 m for this condition. Which result should the chief mate record?
Correct answer: B - Corrected GM 0.75 m; the condition meets the stated GM requirement.
An offshore forecast gives a significant wave height of 4 m. During the forecast period, the bridge observes an individual wave about 6 m high. The junior officer treats this as proof that the forecast understated the sea state. How should the chief mate interpret the observation?
Correct answer: D - The observation can fit the forecast: significant wave height averages the highest third of waves.
For an evening star fix, the navigator can observe any of four three-star groups. All stars are bright enough and the horizon is clear. Which group offers the strongest combination of line-of-position geometry and usable sight altitudes? In each group, altitudes are listed in the same order as azimuths.
Correct answer: C - Azimuths 020°, 140°, 260°; altitudes 30°, 45°, 55°.
At 1000, a fixed lighthouse bears 045°T from the ship. The ship then maintains heading 090°T at 10 knots through the water. A steady current sets 090°T at 2 knots, with no leeway. At 1030, the same lighthouse bears 000°T. Using a local plane chart, what is the ship’s distance from the lighthouse at 1030?
Correct answer: A - 6.0 nautical miles.
The USCG-CM-UNL exam also covers these domains. Drill them in the full free practice test:
The full bank has 1,020 more USCG-CM-UNL questions with explanations.
Continue in the free practice test →
View plans