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USCG Master / Chief Mate of Ocean or Near-Coastal Self-Propelled Vessels of Unlimited Tonnage practice questions are available now; exam metadata is being verified.

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2026 Statistics

Key Facts: USCG Master Unlimited Exam

ONC01

NMC Exam Code

USCG National Maritime Center

~330 questions

Oceans Module Battery

USCG NMC ONC01

90%

Rules of the Road Pass Mark

USCG NMC Q100

70%

Most Module Pass Mark

USCG NMC ONC01

46 CFR 11.404

Master Service Requirement

Code of Federal Regulations

5 years

Credential Validity

USCG Merchant Mariner Credential

The USCG Master / Chief Mate of Unlimited Tonnage exam (NMC ONC01) is the highest U.S. national deck license test, taken by merchant marine officers qualifying under 46 CFR 11.404. The oceans battery runs roughly eight modules totaling about 330 questions: Q100 Rules of the Road (50 questions, 90% to pass), Q101 and Q102 Deck General (50 each, 70%), Q103 Deck Safety (70, 70%), Q104 Deck Safety Stability Problems (15, 70%), Q106 Navigation General Oceans (70, 70%), Q107 Chart Plot (10, 90%), and Q108 or Q109 Navigation Problems. Content spans the COLREGS and Inland Rules; shiphandling, anchoring, cargo stowage and securing, maritime law and ship's business; ship construction, damage control, firefighting and lifesaving; stability and trim including GM, free surface, and loll; and navigation general plus problems in sailings, tides, current, and celestial sights. A Chief Mate endorsement raises to Master without a further professional exam.

Sample USCG Master Unlimited Practice Questions

Try these sample questions to test your USCG Master Unlimited exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Under the International Rules (COLREGS), what does a power-driven vessel underway exhibit at night when not constrained or restricted in any special way?
A.Sidelights and a sternlight only
B.An all-round white light and sidelights
C.Masthead light(s), sidelights, and a sternlight
D.Two all-round red lights in a vertical line
Explanation: Rule 23 requires a power-driven vessel underway to show a forward masthead light, sidelights, and a sternlight (vessels 50 m or more must also show a second, after masthead light higher than the forward one).
2Two power-driven vessels are meeting head-on at night. Under the International Rules, what is each vessel required to do?
A.Both vessels shall stop their engines until the situation is resolved
B.Each shall alter course to port and pass starboard to starboard
C.The vessel to the other's starboard side shall hold course and speed
D.Each shall alter course to starboard and pass port to port
Explanation: Rule 14 states that when two power-driven vessels meet head-on so as to involve risk of collision, each shall alter course to starboard so that each passes on the port side of the other.
3Under the International Rules, in a crossing situation between two power-driven vessels where risk of collision exists, which vessel is the give-way vessel?
A.The vessel that has the other on her own port side
B.The faster of the two vessels regardless of bearing
C.The vessel that has the other on her own starboard side
D.The vessel with the greater draft
Explanation: Rule 15 makes the vessel that has the other on her own starboard side the give-way vessel; she shall keep out of the way and, if circumstances permit, avoid crossing ahead of the other vessel.
4Under the International Rules, a vessel constrained by her draft may, in addition to her normal lights for a power-driven vessel, exhibit which signal?
A.A black diamond shape by day only
B.Two all-round red lights in a vertical line, or a ball by day
C.An all-round red light over an all-round white light
D.Three all-round red lights in a vertical line, or a cylinder by day
Explanation: Rule 28 provides that a vessel constrained by her draught may exhibit three all-round red lights in a vertical line, or a cylinder by day, in addition to the lights prescribed for a power-driven vessel in Rule 23.
5Under the International Rules, what sound signal must a power-driven vessel make in or near an area of restricted visibility when making way through the water?
A.One short blast at intervals of not more than 2 minutes
B.Two prolonged blasts at intervals of not more than 2 minutes
C.One prolonged blast at intervals of not more than 2 minutes
D.Three short blasts at intervals of not more than 1 minute
Explanation: Rule 35(a) requires a power-driven vessel making way through the water to sound one prolonged blast at intervals of not more than 2 minutes.
6Under the Inland Navigation Rules, when two power-driven vessels are crossing and the give-way vessel intends to pass astern of the stand-on vessel, what whistle signal exchange initiates the maneuver?
A.The give-way vessel sounds one short blast; agreement is one short blast in reply
B.The give-way vessel sounds five short and rapid blasts
C.The give-way vessel sounds two short blasts; agreement is two short blasts in reply
D.No whistle signal is exchanged; the rule operates silently
Explanation: Under Inland Rule 34, a proposed maneuver to leave the other vessel on the proposing vessel's port side (passing astern in this crossing) is signaled by two short blasts, with agreement indicated by two short blasts in reply.
7Under both the International and Inland Rules, which statement about the overtaking situation is correct?
A.An overtaking vessel becomes the stand-on vessel once abeam of the other vessel
B.Any subsequent alteration of bearing between the two vessels relieves the overtaking vessel of her duty to keep clear
C.The overtaking vessel must keep out of the way until finally past and clear
D.A vessel is overtaking when approaching from more than 22.5 degrees forward of the other vessel's beam
Explanation: Rule 13 provides that an overtaking vessel shall keep out of the way of the vessel being overtaken, and this duty continues until she is finally past and clear.
8Under the International Rules, a vessel at anchor of 100 meters or more in length is required to do what regarding her lights?
A.Show a single all-round white light forward only
B.Show two all-round red lights in a vertical line
C.Show all-round white lights forward and near the stern, and use working or equivalent lights to illuminate her decks
D.Show sidelights and a sternlight as if underway
Explanation: Rule 30 requires a vessel at anchor to show an all-round white light forward and one at or near the stern; vessels of 100 m or more shall also use available working lights to illuminate their decks.
9Under the International Rules, a vessel engaged in towing where the length of the tow exceeds 200 meters shall exhibit what additional day signal?
A.A black ball where it can best be seen
B.A cylinder where it can best be seen
C.A diamond shape where it can best be seen
D.Two black balls in a vertical line
Explanation: Rule 24(a) requires a vessel towing, when the length of the tow exceeds 200 m, to exhibit a diamond shape where it can best be seen (and three masthead lights in a vertical line at night).
10Under the International Rules, when a vessel is in doubt whether a close-quarters situation is developing or risk of collision exists, she shall:
A.Sound the danger signal and stop
B.Maintain course and speed and continue observing
C.Immediately make a substantial alteration to port
D.Assume risk of collision exists and act accordingly
Explanation: Rule 7(a) provides that if there is any doubt, such risk shall be deemed to exist; the mariner must err on the side of caution and act as though collision risk is present.

About the USCG Master Unlimited Practice Questions

Verified exam format metadata for USCG Master / Chief Mate of Ocean or Near-Coastal Self-Propelled Vessels of Unlimited Tonnage is pending. The practice questions above remain available while official exam length, timing, passing score, fee, and administrator details are reviewed.