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 NBS questions are organized by exam domain, so you can see how each part of the National Barge Supervisor blueprint is tested. Reveal the answer and explanation under each question.
A self-propelled MODU and a supply vessel are in sight of each other on crossing courses in open International waters. Both are ordinary power-driven vessels. The supply vessel is to port and takes early, substantial action to pass astern; continued observations confirm a safe passing distance. The MODU should now:
Correct answer: A - Maintain course and speed while monitoring the passage.
In International waters during fog, a 90-m self-propelled MODU is neither anchored, aground, nor made fast. Her engines remain ready, but she is stopped through the water. Current produces a GPS speed over ground of 2 knots. She is not engaged in towing or work restricting her ability to maneuver. What sound signal is required?
Correct answer: B - Two prolonged blasts, about 2 seconds apart, at intervals not exceeding 2 minutes.
Two power-driven vessels approach head-on in U.S. Inland waters, in sight and 0.4 nautical mile apart. No radiotelephone passing agreement has been made. One vessel sounds one short blast, and the other answers with one short blast. Those exchanged signals establish:
Correct answer: C - An agreement for a port-to-port passage.
At midafternoon, warm, humid air flows across much colder seawater around a MODU. Visibility deteriorates despite a steady 12-knot wind and an overcast sky. There is no precipitation or frontal passage. What process most directly accounts for the fog?
Correct answer: D - Advection fog: moving moist air is cooled by the colder sea surface.
Maintenance of a MODU's fixed carbon dioxide extinguishing system is complete, all personnel are clear of the protected space, and the prescribed restoration checks have passed. The system is governed by 46 CFR 108.444 and is being returned to normal service. In what condition must its manual lockout valve be left?
Correct answer: D - Open and locked in the open position.
For a MODU's planned channel entry, charted depth is 8.8 m and transit draft is 9.0 m. The passage plan requires at least 1.0 m of static under-keel clearance and a current speed no greater than 1.0 knot. Tide heights use the chart datum. Predictions at the entry point are: 0900, tide +0.9 m/current 0.5 knot; 1100, tide +1.6 m/current 0.7 knot; 1300, tide +1.9 m/current 1.6 knots; 1500, tide +1.0 m/current 0.2 knot. Which predicted entry window meets both requirements?
Correct answer: B - 1100.
During a port-to-starboard ballast transfer, the control-room display shows the port tank level falling but the starboard tank level unchanged. The transfer is paused. Independent soundings confirm that the intended starboard tank gained the volume lost from the port tank, and the draft readings are consistent with that transfer. Which fault best explains the discrepancy?
Correct answer: C - A fault in the starboard tank's remote level indication.
A static rigging check concerns a 60-kN load supported symmetrically by two equal sling legs, each at 60 degrees above horizontal. The allowable direct tension in each leg is 40 kN; the crane, master link, and attachment points have adequate capacity. Neglect rigging weight and dynamic effects for this check. Using sin 60 degrees = 0.866, which assessment is valid?
Correct answer: B - Each leg carries about 34.6 kN, within its allowable tension.
A worker has collapsed in an enclosed pump room. Remote sampling shows hydrogen sulfide at 140 ppm and oxygen at 20.8%; personnel outside no longer notice a rotten-egg odor. The alarm has been raised, and a trained team is preparing under the unit's confined-space rescue procedure. Which respiratory protection is appropriate for rescue entry into the measured atmosphere?
Correct answer: A - Full-face self-contained breathing apparatus in pressure-demand mode.
A moored semisubmersible remains 6 m from its target position, within the approved 15-m offset limit. One mooring line carries 920 kN against an 800-kN maximum operating tension. The other lines remain below their individual limits, and average line tension is 540 kN. The overloaded line's minimum breaking load is 2,400 kN. How should the supervisor interpret this condition?
Correct answer: A - One line exceeds its operating limit despite the acceptable position.
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