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The real exam is passed module by module: Rules of the Road requires 90%, most other modules 70%. Chart-plotting modules are taken on paper and not included.
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Master / Mate < 200 GRT is commonly referred to as the 200-ton license, or 200-ton master/mate.
You must pass each module separately. Rules of the Road requires 90%; most other modules require 70%. Chart-plotting modules are worked on paper.
The exam covers 4 modules: Rules of the Road, Deck General, Deck Safety, Navigation General.
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A selection of free questions from the official USCG sample examinations. Use the interactive modules above for timed, scored drills.
INLAND ONLY Which term is NOT defined in the Inland Navigation Rules?
Why: Inland Rule 3 defines seaplane, restricted visibility, and underway, but deliberately omits 'vessel constrained by her draft.' That category exists only in International Rule 3(h) and has no status in inland waters.
INLAND ONLY Which of the following may be displayed by a law enforcement boat?
Why: The Inland Rules specifically authorize law enforcement vessels to display a flashing blue light when engaged in direct law enforcement operations. None of the other signals listed is authorized for that purpose.
INLAND ONLY Which of the following is indicated by a vessel displaying a flashing blue light?
Why: Under the Inland Rules a flashing blue light is reserved for law enforcement vessels engaged in direct law enforcement or public safety activity, so sighting one identifies a police or Coast Guard boat.
BOTH INTERNATIONAL & INLAND By definition which vessel is unable to keep out of the way of another vessel?
Why: Rule 3(g) defines a vessel restricted in her ability to maneuver as one whose work makes her 'unable to keep out of the way of another vessel.' The definitions of towing, fishing, and sailing vessels contain no such wording.
BOTH INTERNATIONAL & INLAND A vessel that is defined as "restricted in her ability to maneuver" is unable to keep out of the way of another vessel due to __________.
Why: Under Rule 3(g) the restriction must arise from the nature of her work, such as dredging, cable laying, or buoy servicing. Draft creates 'constrained by draft' (International only), and exceptional circumstances make a vessel 'not under command.'
INTERNATIONAL ONLY You intend to overtake a vessel in a narrow channel on its port side. The vessel to be overtaken has to take action to permit safe passing. How should you signal your intentions?
Why: International Rule 34(c): when the vessel ahead must take action to permit passing in a narrow channel, the overtaker sounds two prolonged followed by two short blasts, meaning 'I intend to overtake you on your port side' (Rule 9(e)).
INTERNATIONAL ONLY You are operating a vessel in a narrow channel. Your vessel must stay within the channel to be navigated safely. Another vessel is crossing your course from starboard to port, and you are in doubt as to his intentions. According to Rule 9, which statement is TRUE?
Why: When vessels in sight are approaching and you doubt the other's intentions or actions, Rule 34(d) provides the signal of at least five short and rapid blasts. Backing down or bound-to-hold signals are not prescribed.
BOTH INTERNATIONAL & INLAND In which situation do the Rules require both vessels to change course?
Why: Rule 14 requires each power-driven vessel meeting head-on to alter course to starboard, so both act. In crossing situations only the give-way vessel must initially act, and with wind on the same side only the windward sailing vessel keeps clear.
BOTH INTERNATIONAL & INLAND When two power-driven vessels are meeting head-on and there is a risk of collision, which action is required to be taken?
Why: Rule 14: in a head-on meeting with risk of collision, each vessel shall alter course to starboard so they pass port-to-port. Stopping, backing, or the doubt signal are not the prescribed actions.
BOTH INTERNATIONAL & INLAND Which is TRUE of a power-driven stand-on vessel?
Why: Rule 17 requires the stand-on vessel to hold course and speed, but permits her to act as soon as it is apparent the give-way vessel is not taking appropriate action, and requires action when collision becomes unavoidable otherwise.
Which term defines when a vessel is swinging from side to side off course due to quartering seas?
Why: Yawing is the swinging of the bow from side to side off the intended heading, typical in quartering seas. Broaching is being thrown broadside in a trough; rolling is side-to-side rotation; pitchpoling is end-over-end capsizing.
Periodic surveys to renew the load line assignment must be made at which interval?
Why: Load line certificates are issued for five years, with renewal surveys at that interval; annual inspections in between verify nothing affecting the assignment has changed.
Your vessel is broken down and rolling in heavy seas. How can you reduce the danger of capsizing?
Why: A sea anchor streamed from the bow holds the vessel's head into the seas, keeping her from lying beam-on in the trough where rolling and capsize risk are greatest. Shifting passengers or working the rudder will not control a powerless vessel.
U.S. regulations require all tankships of 150 GT and above and all other ships of 400 GT and above, to prepare and maintain which of the following?
Why: U.S. regulations implementing MARPOL (33 CFR 151.26) require a Coast Guard approved Shipboard Oil Pollution Emergency Plan (SOPEP) on oceangoing tankships of 150 GT and above and other ships of 400 GT and above.
A marine chemist issues gas free certificates and is certified by which organization?
Why: Marine chemists who issue gas-free certificates are certificated by the National Fire Protection Association, which administers the marine chemist qualification program.
Cargo vessels being navigated, and fitted with emergency lighting and power systems, shall have their emergency systems tested at which interval?
Why: Regulations require the emergency lighting and power systems of cargo vessels being navigated to be tested at least once each week, so the systems are proven before an actual emergency.
How should a look-out, in the merchant service, report sightings?
Why: Lookouts report contacts in relative bearings measured from the bow (e.g., 'broad on the starboard bow'). No compass is needed at the lookout station, and the bridge instantly knows where to look relative to the ship's head.
The most likely time for oil pollution while bunkering is when __________.
Why: Topping off is when tanks are nearly full and an overflow can occur in seconds; flow may still be substantial and the remaining ullage is small, making it the most likely moment for a spill.
Inflatable liferafts shall be serviced at an approved servicing facility every 12 months or not later than the next vessel inspection for certification. However, the total elapsed time between servicing cannot exceed which time frame?
Why: Inflatable liferafts are serviced annually, but the interval may extend to the next inspection for certification provided the total elapsed time between servicings never exceeds 17 months.
How would the exhaust of a properly operating diesel engine appear?
Why: A properly operating diesel burns its fuel completely, so the exhaust is nearly invisible. Blue smoke means burning lube oil, black means overload or incomplete combustion, and white can mean water or unburned fuel.
Which is the region containing 3/4 of the mass of the atmosphere and to which are confined such phenomena as clouds, storms, precipitation and changing weather conditions?
Why: The troposphere, the lowest layer of the atmosphere, contains about three quarters of its mass and nearly all its water vapor, so clouds, precipitation, storms, and changing weather occur there.
A safe water daymark has what shape?
Why: Safe water daymarks are octagonal and colored red and white. Triangles are starboard-hand marks and squares are port-hand marks, so safe water gets its own distinctive eight-sided shape.
Which agency publishes the Light Lists?
Why: The U.S. Coast Guard publishes the Light List, describing lights, buoys, and other aids to navigation in U.S. waters. Charts and tide data come from the National Ocean Service.
Which weather element cannot be measured accurately while on board a moving vessel?
Why: Estimating visibility requires reference objects at known distances, and at sea there are none, so it can only be roughly judged. Wind, temperature, and pressure are measured by instruments, with corrections for the vessel's motion.
Why is a VLCC (100,000 DWT+) with a 30,000 Shaft Horsepower Steam Turbine slow to respond to engine movements, and has less stopping power than normal ships?
Why: A loaded VLCC has enormous displacement but comparatively modest horsepower, a small power-to-weight ratio, so the engine has little leverage over the ship's huge momentum, making her slow to respond and hard to stop.
Which states the requirements for the access to a cargo pumproom in a tank vessel carrying grades C or D liquid cargo?
Why: Regulations require pumproom access on these tankships to be from the open deck, so personnel never pass through enclosed spaces where cargo vapors could accumulate and escape or rescue is direct.
Who must approve the vessel's trim and stability booklet?
Why: For U.S. inspected vessels the trim and stability booklet must be approved by the Coast Guard, which reviews the stability data and inclining experiment results during plan approval.
Who has the authority to grant an alternate procedure for oil transfer operations?
Why: Under 33 CFR 156.107 the Captain of the Port may consider and approve alternatives to the required oil transfer procedures when they provide an equivalent level of safety and pollution protection.
What is the period of validity of a Merchant Mariner Credential?
Why: A Merchant Mariner Credential is issued for a five-year term and must be renewed before it expires.
A ship station license for your radiotelephone is valid for which of the following terms?
Why: FCC ship station licenses are issued for a ten-year term.
A drill must be conducted in the use of the line throwing appliance. How often is this drill required to be conducted?
Why: Regulations require a drill in the use of the line-throwing appliance at least once every three months.
Which defines the function of a spark arrestor?
Why: A spark arrestor traps glowing carbon particles in an engine's exhaust, preventing them from escaping the exhaust system and igniting flammable vapors or materials nearby.
Which term is used to describe the horizontal port or starboard movement of a vessel?
Why: Sway is the bodily side-to-side (translational) motion of a vessel. Yaw is rotation about the vertical axis, surge is fore-and-aft bodily motion, and heave is vertical bodily motion.
If a vessel takes a sudden, severe list or trim from an unknown cause, which action should you take FIRST?
Why: A sudden unexplained list could be negative GM, flooding, or shifted weight, and each requires a different remedy. Counterflooding or shifting weight against the wrong cause, such as negative GM, can capsize the vessel, so find the cause first.
While proceeding up a channel on course 010° per gyrocompass, you notice a pair of range lights in alignment with the masts of your vessel when viewed forward. A check of the chart shows the range to be 009°T and the variation to be 15°W. If the ship's course is 026°psc, what is the deviation for the present heading?
Why: Range true 009 plus variation 15W gives 024 magnetic. On the range dead ahead the compass reads 026 psc. Deviation = magnetic minus compass = 024 - 026 = 2W.
The shoreline shown on nautical charts of areas affected by large tidal fluctuations is usually the line of mean __________.
Why: The charted shoreline in tidal areas is the mean high water line, the average of the high tides, so charted land may be surrounded by water at lower stages. Soundings, by contrast, use a low-water datum.
Two well-developed high-pressure areas may be separated by which item?
Why: An elongated extension of low pressure is called a trough, while an elongated high is a ridge. Two well-developed highs are therefore separated by a trough of low pressure between them.
What do red sectors of navigation lights warn mariners of?
Why: Red sectors of lights are positioned to cover dangers such as shoals or nearby land; when the light appears red, your line of bearing crosses the charted danger area.
What does the lubber's line on a magnetic compass indicate?
Why: The lubber's line is the fixed mark on the compass bowl aligned with the vessel's fore-and-aft line. Reading the card against it gives the vessel's compass heading, not north or any bearing.
What are Cirrus clouds primarily composed of?
Why: Cirrus clouds form at high altitudes where temperatures are well below freezing, so they are composed of ice crystals, giving them their thin, wispy, fibrous appearance.
The buoy symbol printed on your chart is leaning to the northeast. What does this indicate?
Why: Buoy symbols are drawn leaning on charts purely for legibility; the tilt has no navigational meaning. The buoy's position is the small circle or dot at the base of the symbol.
Information about the pilotage available at Miami harbor may best be obtained from which publication?
Why: The United States Coast Pilot supplements charts for U.S. waters with information on pilotage, anchorages, bridges, and port facilities. Sailing Directions and the World Port Index cover foreign ports.
How can you follow the approach of a dangerous cyclonic storm?
Why: Following a storm's approach requires forecast and synoptic information: weather maps, fax charts, broadcast forecasts, or news reports. Sea temperature and observation handbooks do not show a storm's position and movement.
Which condition(s) is(are) necessary for the formation of dew?
Why: Dew forms on clear, calm nights when surfaces radiate heat away and cool below the air's dew point; clouds blanket that radiational cooling. A surface warmer than the dew point would prevent condensation, and wind mixes the air.
While navigating in fog off a coastline of steep cliffs, you hear the echo of the ship's foghorn 3 seconds after the signal was sounded. What is the distance to the shore?
Why: Sound travels about 1,100 feet per second in air. A 3-second echo means 1.5 seconds each way: 1.5 x 1,100 = 1,650 feet, which is 550 yards.
Which of the following is a standard correction applied to the reading of an aneroid barometer?
Why: Aneroid barometer readings are corrected for the instrument's height above sea level so they represent sea-level pressure. Temperature and latitude corrections apply to mercurial barometers, not aneroids.
To find the specific phase characteristic of a lighthouse on a sound of the United States you would use which reference?
Why: The Light List gives each light's complete characteristic, including rhythm, period, and colors, in more detail than the chart abbreviation. The Coast Pilot describes waters generally but is not the reference for light characteristics.
The four standard light colors used for lighted aids to navigation are red, green, white, and __________.
Why: Lighted aids to navigation use red, green, white, and yellow. Yellow lights mark special-purpose aids; blue, purple, and orange are not standard light colors for aids to navigation.
What kind of pressure systems travel in tropical waves?
Why: Tropical waves are westward-moving troughs of low pressure in the trade-wind belt; convergence and showers accompany the wave axis, and some waves develop into tropical depressions or hurricanes.
When using GPS without Selective Availability, what can you expect your horizontal accuracy to be of the unit?
Why: With Selective Availability discontinued, standard civilian GPS gives horizontal accuracy on the order of 20 meters or better. 100 meters was the SA-degraded figure, and 3 meters requires differential corrections.
What is the period of validity of a De-Rat certificate?
Why: Deratting and deratting exemption certificates are valid for six months under the international sanitary regulations.
When should the lubricating oil be changed on a heavy-duty diesel engine?
Why: Heavy-duty diesels follow scheduled preventive maintenance: lube oil is changed at the specified service interval of operating hours or time. Color and feel are unreliable, since oil normally darkens quickly in service while still protecting the engine.
You are docking a vessel. When are the wind and current most favorable in this situation?
Why: With wind and current from ahead and parallel to the pier, you can stem them, keeping steerageway with little speed over the ground for maximum control. Cross-setting forces push you onto or off the berth unpredictably.
Which term defines the total weight of a box containing cargo?
Why: Gross weight is the contents plus the container; tare weight is the empty box alone; net weight is the cargo by itself. Gross equals net plus tare.
An alien crewmember with a D-1 permit leaves the vessel in a U.S. port and fails to return. The first report you make should be to which organization?
Why: A D-1 landing permit is issued under immigration law, so a crewmember who fails to return must first be reported to the immigration authorities, who control alien crew landings and departures.
Which agency must approve the safety equipment on board inspected vessels?
Why: On inspected vessels, lifesaving and other safety equipment must be of types approved by the U.S. Coast Guard, the agency that inspects and certificates the vessel. OSHA and private safety organizations have no such approval authority.
A vessel that has which of the following will ensure that it will keep its draft at or below the load line mark?
Why: The load line exists to guarantee reserve buoyancy, the watertight volume above the waterline. A vessel that preserves adequate reserve buoyancy is by definition floating at or above the minimum freeboard the mark requires.
According to Coast Guard Regulations (46 CFR), when loading, or discharging oil in bulk at a dock, which of the following signals must be displayed?
Why: Coast Guard regulations (33 CFR 35.30-1) require a red warning signal during bulk oil transfer at a dock: the red flag (flag Bravo) by day or a red light at night, warning others of the hazardous operation.
Close link chain of not less the 3/4" (or the wire rope equivalent) is required for lashing deck cargoes of timber. What size flexible wire rope would provide the strength equivalent to 3/4" chain, using a safety factor of 5?
Why: Wire rope is weaker than chain of the same nominal size. The timber deck cargo regulations' equivalency, applying a safety factor of 5, requires 1-inch flexible wire rope to match the strength of 3/4-inch close link chain.
Where a propeller shaft passes through the hull, which device prevents water from entering the hull?
Why: The stuffing box surrounds the shaft where it penetrates the hull; packing compressed by a gland seals against sea water while still letting the shaft rotate. A sea cock is a hull valve, not a shaft seal.
What power source actuates a solenoid valve?
Why: A solenoid is a coil of wire; electric current through the coil creates a magnetic field that moves a plunger to open or close the valve. No hydraulic, pneumatic, or mechanical input operates it.
The Master of a cargo or tank vessel shall be responsible that each lifeboat, except those free-fall launched, is lowered to the water with crew and maneuvered. Which time interval is this action required?
Why: Regulations (46 CFR 199.180) require each lifeboat, except free-fall boats, to be launched, lowered to the water with its assigned crew, and maneuvered at least once every three months, normally during an abandon-ship drill.
Which extinguishing agent is most effective on a mattress fire?
Why: A mattress fire is a deep-seated Class A fire. Water soaks into the material, cooling below ignition temperature throughout. Gas agents like CO2 or Halon only smother the surface, so the fire can rekindle inside.
Your vessel has been damaged and is partially flooded. The first step to be taken in attempting to save the vessel is to __________.
Why: Damage control priority is to stop the flooding from spreading: establish and hold flooding boundaries first. Pumping, plugging, and stability calculations come after the water is contained, otherwise flooding may outpace everything else you do.
In ship construction, which is TRUE concerning frame spacing?
Why: Frames are spaced closer together at the bow and stern because those areas take extra stresses, panting and pounding from wave impact, so they need more structural support than the midbody.
When an azimuth of the Sun has been taken and the deviation of the standard magnetic compass computed, the watch officer should record the results __________.
Why: Computed deviations are recorded in the compass deviation log so a running record of deviation on various headings is maintained and trends or changes can be detected. The deviation card is only updated after adjustment.
Ultrasonic testing is used to determine the thickness of a vessel's shell plating and which other testing?
Why: Ultrasonic testing sends sound pulses through metal and reads reflections, so besides gauging plate thickness it detects subsurface defects in welds, voids, cracks, and lack of fusion invisible from the surface.
The safety discs on carbon dioxide cylinders are set to release at 2,700 psi. Under normal circumstances this pressure will be reached at which temperature?
Why: CO2 cylinder pressure rises with temperature. At about 135°F a normally charged cylinder reaches roughly 2,700 psi, so the safety disc is set to rupture there, venting the gas before the cylinder can burst.
You must medevac a critically injured seaman by helicopter hoist. Which statement is TRUE?
Why: Rotor downwash will blow loose items like baseball hats off, creating debris that can be drawn into the helicopter's rotors or engine. The drop line must never be secured to the ship, and the sling goes under the armpits.
When evacuating a seaman by helicopter lift, which statement is TRUE?
Why: Flags give the pilot a visible indication of apparent wind direction over the ship. The vessel should maintain steady way with wind on the bow, not stopped, and the static-charged drop line is never secured to the ship.
BOTH INTERNATIONAL & INLAND When action to avoid a close-quarters situation is taken, a course change alone may be the most effective action provided that __________.
Why: Rule 8 says an alteration of course alone may be the most effective action if it is substantial (large enough to be readily apparent), made in good time, and does not create another close-quarters situation. Small successive changes are to be avoided.
BOTH INTERNATIONAL & INLAND You are approaching another vessel at night. You can see both red and green sidelights and, above the level of the sidelights, three white lights in a vertical line. Which vessel is required to have these lights?
Why: Under Rule 24, a towing vessel whose tow extends more than 200 meters astern shows three masthead lights in a vertical line, plus sidelights, which explains seeing red, green, and three white lights.
INLAND ONLY When two power-driven vessels are meeting on the Great Lakes, Western Rivers, or waters specified by the Secretary, where there is a current, which vessel shall sound the first passing signal?
Why: Inland Rule 14(d): on these waters the downbound vessel with a following current has the right-of-way, proposes the manner of passage, and sounds the first signal, because the current makes her harder to stop and maneuver.
BOTH INTERNATIONAL & INLAND When is your vessel traveling at a "safe speed" as defined in the COLREGS?
Why: Rule 6 defines safe speed as one allowing proper and effective action to avoid collision and stopping within a distance appropriate to conditions. It is not measured against other vessels, wake, or simply stopping within visibility range.
INLAND ONLY A law enforcement vessel patrolling a marine regatta may exhibit a flashing blue light or which of the following alternates?
Why: Under the Inland Rules, a vessel engaged in public safety activities, such as patrolling a regatta, may display an alternately flashing red and yellow identity light as the alternative to the law-enforcement flashing blue light.
BOTH INTERNATIONAL & INLAND Which is TRUE for a vessel using a traffic separation scheme?
Why: Rule 10 directs vessels to avoid anchoring within a traffic separation scheme or near its terminations, where converging traffic concentrates. Crossing, when obliged, must be at as near a right angle as practicable, not a small angle.
BOTH INTERNATIONAL & INLAND You are approaching another vessel on crossing courses. She is about one mile distant and is on your starboard bow. You believe she will cross ahead of you but she sounds a whistle signal of five short blasts. Which action should you take?
Why: Five short blasts is the danger/doubt signal (Rule 34(d)), she doubts you will keep clear. Rule 8 requires action that is substantial and made in ample time: a large, readily apparent course change, slowing if necessary.
BOTH INTERNATIONAL & INLAND Your power-driven vessel is stopped and making no way, but is not in any way disabled. Another vessel is approaching you on your starboard beam. Which statement is TRUE?
Why: A vessel stopped but not anchored or disabled is still a power-driven vessel underway. Under Rule 15, with the other vessel on your starboard side in a crossing situation, you are the give-way vessel; being stopped grants no privilege.
BOTH INTERNATIONAL & INLAND Which vessel should not impede the navigation of a power-driven vessel?
Why: Rule 18(e) requires a seaplane on the water to keep well clear of all vessels and avoid impeding their navigation. The other vessels listed are ones a power-driven vessel must keep out of the way of.
INLAND ONLY For the purpose of the Inland Navigation Rules, the term "Inland Waters" includes which of the following?
Why: The Inland Rules define inland waters as U.S. navigable waters shoreward of the demarcation lines, plus the Western Rivers (Mississippi River System). The Great Lakes are included only on the U.S. side, and waters seaward of the lines are COLREGS waters.