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These 10 free NM1N questions are organized by exam domain, so you can see how each part of the National Master 100 NC (NM1N) blueprint is tested. Reveal the answer and explanation under each question.
At night in clear visibility under International Rules, a yacht under sail alone approaches your power-driven launch from astern. Initially, the yacht can see your sternlight but neither sidelight. As it draws up on your port quarter, your port sidelight becomes visible. How does that change affect the vessels' obligations?
Correct answer: B - The yacht remains the overtaking vessel and must keep clear until finally past and clear.
Your power-driven vessel and another are in sight of each other, crossing in open water under International Rules. The other vessel is on your port bow and has made an early, substantial turn to pass well astern. Successive observations confirm a safe passing distance, and there are no other navigation hazards. How should you handle your vessel while that maneuver takes effect?
Correct answer: A - Hold course and speed, and continue checking the passing situation.
You are conning a power-driven vessel in U.S. Inland waters. Another power-driven vessel crosses nearby, in sight at a distance of 0.3 nautical mile, and sounds two short blasts. In this encounter, the signal means:
Correct answer: C - I intend to leave you on my starboard side.
A launch lies port side to a quay, with the current tending to carry it ahead along the berth. The master needs a line led nearly parallel to the quay to check that forward movement. Which lead provides the required restraint?
Correct answer: C - From a forward cleat to a shore bollard well aft of that cleat.
At unchanged cruising rpm, the port diesel's temperature rises and the cooling-water discharge from its wet exhaust drops markedly. The engine has a closed freshwater circuit cooled by a seawater heat exchanger; the coolant level was correct before departure. The master secures the engine once navigation permits. Which fault best accounts for both observations?
Correct answer: D - A seawater strainer clogged enough to restrict raw-water flow.
An intact passenger vessel remains upright after a fuel transfer. The loading calculation shows that its free-surface-corrected GM has fallen from 0.68 m to 0.24 m, with no change in displacement. Both conditions comply with the vessel's approved loading limits. The new condition is best described as:
Correct answer: D - More tender, with less initial resistance to heeling but still a positive initial righting tendency.
A fire is confirmed in an enclosed engine compartment fitted with a fixed carbon-dioxide system. Everyone is accounted for outside the space, the engines are stopped, and the fuel supply is shut off. The compartment's ventilation fan is still running. What must be completed before the system is discharged?
Correct answer: A - Stop the fan and close the compartment's ventilation openings.
The plotted course for a coastal leg is 008° true. Variation is 11° west, and the applicable deviation is 3° east. With negligible current and leeway, what compass course should the helmsman steer?
Correct answer: A - 016° compass
Warm, moisture-laden air moves over substantially colder coastal water. Dense fog persists through the afternoon even though sunshine is reported above the fog layer. What mechanism best explains the loss of visibility?
Correct answer: C - Advection fog formed when moist air is cooled over colder water.
A lighthouse is the only charted landmark visible during a coastal passage. It bears 000° true at 0800 and 315° true at 0824. Between observations, your vessel maintains 090° true at 7.5 knots through the water, with no current or leeway. Both bearings are taken from the vessel toward the lighthouse. Which position at 0824 is consistent with both observations?
Correct answer: B - 3.0 nautical miles east and 3.0 nautical miles south of the lighthouse.
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