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These 10 free NM51GI questions are organized by exam domain, so you can see how each part of the National Master 500/1600 GL and Inland (NM51GI) blueprint is tested. Reveal the answer and explanation under each question.
On open inland waters in clear visibility, a power-driven vessel approaches on your port side on a crossing course. Before the encounter becomes close, she makes a substantial alteration to pass astern of your power-driven vessel. Successive observations confirm that her action is effective. Which bridge order preserves the appropriate response?
Correct answer: C - Maintain course and speed while continuing to monitor the passing situation.
The bridge log of a 38 m power-driven vessel in fog records: 'Engine stopped; no way through the water; drifting with the current at 2 knots over the ground.' She is neither anchored nor aground, and propulsion and steering remain available. Her prescribed sound signal, at intervals not exceeding two minutes, is:
Correct answer: B - Two prolonged blasts, about two seconds apart.
The lookout reports a vessel displaying three all-round lights vertically, red-white-red. Two additional all-round green lights are vertical on that vessel's starboard side, and two all-round red lights are vertical on her port side. In otherwise suitable navigation conditions, what information do these lights give you?
Correct answer: D - She is restricted by underwater work; her starboard side is the indicated passing side.
A single-screw vessel is making steady headway close to the starboard bank of a narrow channel. The bow begins to sheer to port while the stern moves toward the bank. The rudder indicator follows helm orders correctly, and no other vessel is passing. What most directly explains this combination of movements?
Correct answer: A - Bank cushion at the bow combined with bank suction at the stern.
A static lift has a total suspended weight of 8 tonne-force. Two identical sling legs share the load equally, and each has a working load limit of 6 tonne-force in the stated arrangement. At 30° above the horizontal, the planned rig is overloaded. Increasing both angles to 60° above the horizontal would produce which result? Ignore sling weight and dynamic effects.
Correct answer: C - 4.6 tonne-force per leg; within the working load limit.
Departure loading data: displacement 1,500 tonnes; KM 6.20 m; KG 5.35 m before free-surface correction; combined free-surface moment of all slack tanks 360 tonne-metres, already adjusted for liquid density. The approved loading instructions require a corrected GM of at least 0.50 m for this condition. Which entry belongs on this part of the stability check?
Correct answer: D - GM 0.61 m; the stated minimum is satisfied.
'No smoke is escaping now. Shall we restart the ventilation?' The engineer makes this request just after fixed CO2 has been discharged into a sealed machinery space. All personnel are accounted for, no rescue entry is needed, and boundary temperatures remain elevated. The master should direct the crew to:
Correct answer: B - Keep it sealed and continue boundary monitoring; opening it now risks re-ignition.
At a channel junction, you are proceeding in the conventional direction of buoyage under the U.S. lateral system. A buoy ahead has horizontal red and green bands, with red uppermost. Both branches are navigable for your vessel. To follow the preferred channel, how should you pass this buoy?
Correct answer: A - Leave it to starboard and take the branch to its left.
After a steel equipment cabinet is installed near the magnetic compass, checks against charted transits show new errors that differ substantially with the vessel's heading. The checks are made in the same harbor on the same day. The gyro checks correctly against those transits. Which error should be investigated first?
Correct answer: A - Magnetic-compass deviation caused by the changed onboard magnetic environment.
At 1012, a fixed lighthouse bears 045°T. Your vessel then makes good 090°T at 12 knots until 1028, when the same lighthouse bears 315°T. Both bearings are corrected, and the stated ground track and speed are constant. Where does the 1028 running fix place the vessel relative to the lighthouse?
Correct answer: D - 1.6 NM east and 1.6 NM south.
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