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MARINA OIC-NW Theoretical Exam study materials
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MARINA OIC-NW Theoretical Exam practice questions

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Question 1Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

On a Mercator chart, a straight line drawn between two positions represents which of the following?

  1. A rhumb line of constant true course Correct answer.
  2. A small circle of equal distance from the pole
  3. A line of constant magnetic bearing
  4. A great circle track

Explanation

The Mercator projection is constructed so that all meridians and parallels appear as straight lines and the scale expands with latitude in the same ratio as the meridians converge. A straight line on the chart therefore cuts every meridian at the same angle, which is the definition of a rhumb line. The great circle track appears as a curve concave toward the nearer pole, except on the equator or a meridian.

Question 2Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

A vessel steams 090° True for 12 nautical miles and then 180° True for 12 nautical miles. Ignoring current and leeway, what is the true bearing from the starting position to the final position?

  1. 180°
  2. 135° Correct answer.
  3. 090°
  4. 225°

Explanation

The track forms a right-angled triangle with the two 12-mile legs as equal sides, so the closing bearing bisects the angle between east and south. East is 090° and south is 180°, and the bisector between them is 135°. The distance run back to the start would be about 17 nautical miles on that bearing.

Question 3Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

What does a charted sounding of '12' printed in the open sea area of a metric chart indicate?

  1. Distance of 12 cables to the nearest hazard
  2. Depth of 12 fathoms below the keel
  3. Depth of 12 metres below chart datum Correct answer.
  4. Height of 12 metres above mean sea level

Explanation

On metric charts, soundings are shown in metres and decimetres below chart datum, which is normally the level of lowest astronomical tide. A whole number such as 12 therefore means 12 metres of water at datum. Fathom-based charts would show the unit in the chart title and use a different figure style.

Question 4Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

Which statement correctly describes the relationship between variation and deviation?

  1. Variation is caused by the ship's machinery; deviation is caused by the earth's magnetic field
  2. Variation is the angle between true and magnetic north; deviation is the error caused by the vessel's own magnetic field Correct answer.
  3. Variation changes with the ship's heading; deviation changes with geographic position
  4. Variation applies only to gyrocompasses; deviation applies only to magnetic compasses

Explanation

Variation is the angular difference between the true meridian and the magnetic meridian at the vessel's position, and it changes as the vessel moves. Deviation is the additional error induced in the compass by the ship's own magnetism and by nearby electrical equipment. Compass error is the algebraic sum of variation and deviation.

Question 5Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

A position fix is obtained from a single visual bearing and a simultaneous sounding. Which limitation applies to this fix?

  1. The fix requires a second bearing from the same object
  2. The fix is unreliable because a single bearing cannot define a position line
  3. The sounding must fall on a sharply defined depth contour to give a usable position line Correct answer.
  4. The sounding must be corrected for tidal stream before it can be used

Explanation

A sounding provides a position line only where the seabed slope is steep enough for the depth to change quickly over a short distance, such as on a well-defined contour. On a flat bottom a small depth error corresponds to a large distance error, making the sounding valueless as a line of position. The depth must also be reduced to chart datum using the tide before comparing it with the chart.

Question 6Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

A vessel's gyrocompass reads 045° while the true bearing of a distant landmark is 048°. What is the gyro error and the corresponding gyro bearing of a second object whose true bearing is 200°?

  1. 3° high, so the gyro bearing is 197°
  2. 3° high, so the gyro bearing is 203°
  3. 3° low, so the gyro bearing is 203°
  4. 3° low, so the gyro bearing is 197° Correct answer.

Explanation

Comparing the gyro reading with the true bearing shows the gyro reads 3° less than truth, so the error is 3° low, and corrections are applied by adding 3° to gyro readings. For a true bearing of 200°, the gyro should read 200° minus 3°, which is 197°.

Question 7Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

When planning a coastal passage, what is the purpose of marking a 'no-go' area on the chart?

  1. To show the areas in which the echo sounder is unreliable
  2. To define water the vessel must avoid, such as shoals or traffic separation scheme exclusion zones, so the planned track stays in safe water Correct answer.
  3. To indicate where the vessel may anchor without permission
  4. To record the positions at which the vessel intends to alter course

Explanation

No-go areas are drawn around hazards, shoals, and regulated zones so that the intended track and its contingency margins remain clear of them. They support the passage plan by making the safe-water corridor explicit before the voyage begins. They are a planning tool and do not replace the keeping of a proper lookout.

Question 8Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

A vessel is steering 000° True at 10 knots when a current sets 090° at 2 knots. What is the vessel's speed made good over the ground?

  1. About 12.0 knots
  2. About 10.0 knots
  3. About 8.0 knots
  4. About 10.2 knots Correct answer.

Explanation

The current acts at right angles to the vessel's heading, so the resulting ground vector is the hypotenuse of a right triangle with sides of 10 and 2 knots. The square root of 104 is about 10.2 knots. The vessel's course made good would also be shifted toward 090° by about 11 degrees.

Question 9Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

A vessel's echo sounder indicates 20 metres while the charted depth at the position is 14 metres and the chart datum is lowest astronomical tide. What does this indicate about the height of tide?

  1. The height of tide is about 6 metres above chart datum Correct answer.
  2. The height of tide is about 6 metres below chart datum
  3. The height of tide is about 34 metres above chart datum
  4. The height of tide cannot be determined without the vessel's draft

Explanation

If the sounder reading is corrected for transducer depth and draft so that it represents total water depth, the height of tide is the difference between the observed depth and the charted depth. Here 20 metres minus 14 metres gives about 6 metres above chart datum. In practice the sounder reading must first be reduced to the depth below the waterline and then adjusted for the vessel's draft.

Question 10Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

Which method gives the most reliable position fix when a vessel is approaching a coast at night with few identifiable lights?

  1. Estimated position derived from the log and the planned track
  2. Dead reckoning from the last reliable fix
  3. A single bearing of a lighthouse taken with a hand-bearing compass
  4. Radar range and bearing of a prominent headland combined with a second radar range Correct answer.

Explanation

Radar provides independent ranges and bearings that do not depend on visual identification of lights, and crossing two position lines gives a fix with a known angle of cut. Combining a range and bearing from one object with a range from another gives a robust check on the vessel's position. Dead reckoning and estimated positions accumulate error and cannot confirm the vessel's actual position.

Question 11Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

On a chart, a light is described as 'Fl(3) R 10s 25m 12M'. What does the '12M' indicate?

  1. The distance of the light from the nearest port in nautical miles
  2. The period of the light in minutes
  3. The nominal range of the light in nautical miles Correct answer.
  4. The height of the light above chart datum in metres

Explanation

In the charted light description, the final figure with an M suffix is the nominal range in nautical miles, the distance at which the light is visible in clear weather with a meteorological visibility of 10 nautical miles. The '25m' is the elevation of the light above chart datum. The 'Fl(3) R 10s' shows three red flashes in a ten-second period.

Question 12Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

A vessel is on a course of 090° True and observes a buoy bearing 045° True at a range of 2 nautical miles. What is the bearing and distance of the vessel from the buoy?

  1. 225° True at 2 nautical miles Correct answer.
  2. 135° True at 2 nautical miles
  3. 045° True at 2 nautical miles
  4. 315° True at 2 nautical miles

Explanation

The reciprocal bearing is found by adding or subtracting 180°, so 045° becomes 225°. The range is unchanged because the distance between the two points is the same in either direction. This reciprocal relationship is used constantly when plotting a bearing from the vessel to an object and then working from the object back to the vessel.

Question 13Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

What is the main advantage of a transverse Mercator projection for a chart of a narrow coastal strip?

  1. Scale distortion is small near the central meridian, which suits a long north-south coastal area Correct answer.
  2. All rhumb lines appear as straight lines at any orientation
  3. Great circles appear as straight lines everywhere on the chart
  4. The chart can show the entire globe with a single uniform scale

Explanation

The transverse Mercator projection is constructed as if the cylinder touched the globe along a meridian rather than the equator, so distortion is least near that central meridian and grows with distance from it. This makes it well suited to charts of long, narrow areas running north-south. It does not preserve all rhumb lines as straight lines, which is a property of the ordinary Mercator projection.

Question 14Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

A vessel's log reads 120.4 at 0800 and 138.9 at 1200. What is the average speed through the water over the period?

  1. 9.3 knots
  2. 18.5 knots
  3. 4.6 knots Correct answer.
  4. 3.7 knots

Explanation

The distance run is 138.9 minus 120.4, which equals 18.5 nautical miles over four hours. Dividing 18.5 by 4 gives 4.625, or about 4.6 knots. This is speed through the water and must be combined with current to obtain speed made good.

Question 15Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

When plotting a running fix using two bearings of the same object taken at different times, what must be applied to the first position line?

  1. The height of tide at the time of the first observation
  2. The vessel's course and distance run between the two observations Correct answer.
  3. The variation at the position of the object
  4. The deviation of the compass at the second observation

Explanation

A running fix advances the earlier position line along the vessel's track by the distance run between observations, producing an advanced line that can be crossed with the later bearing. The advance must use course and speed made good, corrected for current and leeway where known. Errors in the advance transfer directly into the resulting fix.

Question 16Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

A chart shows a drying height of 2.5 metres over a shoal. If the height of tide is 1.8 metres, what depth of water exists over the shoal?

  1. There is 4.3 metres of water over the shoal
  2. The shoal is still 0.7 metres above water Correct answer.
  3. There is 1.8 metres of water over the shoal
  4. There is 0.7 metres of water over the shoal

Explanation

A drying height means the feature is above chart datum, so the tide must first cover that height before any water lies over it. With 1.8 metres of tide against a 2.5-metre drying height, the shoal remains 0.7 metres above the water surface. The area is therefore still unsafe to cross at that state of tide.

Question 17Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

Which of the following is the correct sequence of steps when laying off a course to steer to counteract a known current?

  1. Plot the ground track, then add the current vector at the destination to find the course
  2. Plot the current vector first, then draw the course from the end of the current vector to the destination
  3. Steer directly along the ground track and increase speed to offset the current
  4. Plot the desired ground track, lay off the current vector from the start, then swing the speed through the water to intersect the track Correct answer.

Explanation

The construction begins with the required track over the ground and the current vector drawn from the starting point for the duration of the run. An arc of radius equal to the speed through the water, centred on the end of the current vector, cuts the ground track at the point that defines the course to steer. The resulting heading is offset up-current so that the vessel's actual track follows the intended line.

Question 18Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

On an Electronic Chart Display and Information System, what is the significance of the safety contour setting?

  1. It defines the depth at which the system warns of unsafe water ahead of the vessel Correct answer.
  2. It sets the range scale at which the chart is displayed
  3. It determines the colour of the vessel's own ship symbol
  4. It fixes the interval between position updates from the receiver

Explanation

The safety contour is a user-set depth, chosen with reference to the vessel's draft and under-keel clearance, that the system uses to distinguish safe from unsafe water. Areas shoaler than the contour are highlighted and trigger alarms when the vessel's predicted position approaches them. It is a planning and monitoring aid and does not replace the use of official paper charts and notices to mariners.

Question 19Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

A vessel is steering 270° True and a light is observed bearing 315° True. What is the relative bearing of the light?

  1. 135° on the starboard quarter
  2. 45° on the port bow
  3. 315° on the port beam
  4. 45° on the starboard bow Correct answer.

Explanation

Relative bearing is the true bearing minus the vessel's heading, measured clockwise from the bow. Here 315° minus 270° gives 45°, which lies to starboard of the heading. The light is therefore 45° on the starboard bow.

Question 20Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

Why is it important to allow for the chart's horizontal datum when transferring a position from a satellite positioning system to a paper chart?

  1. The datum determines the magnetic variation to be applied to bearings
  2. A mismatch between the datum of the fix and the chart datum shifts the plotted position by a potentially significant amount Correct answer.
  3. The chart's horizontal datum determines the height of tide at the position
  4. The datum affects only the depth soundings and not the latitude and longitude

Explanation

Satellite systems typically output positions on a global datum such as WGS 84, while many older charts are referenced to a local datum. The difference between the two can be large enough to place the plotted position on the wrong side of a hazard. Modern charts state their datum, and the receiver should be set to match it or the shift applied manually.

Question 21Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

A vessel at anchor observes a conspicuous tower bearing 020° True and a second tower bearing 110° True. What is the angle of cut between the two position lines?

  1. 130°
  2. 20°
  3. 90° Correct answer.
  4. 45°

Explanation

The angle of cut is the smaller angle between the two position lines, found by subtracting the two bearings. Here 110° minus 020° gives 90°, which is close to the ideal crossing for a visual fix. Angles near 90° give the smallest position error for a given bearing error, while very acute or very obtuse crossings magnify uncertainty.

Question 22Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

Which statement best describes the role of the 'wheel-over point' in passage planning?

  1. It is the position at which the pilot boarding ground is marked on the chart
  2. It is the position at which the vessel's clocks are changed for the new time zone
  3. It is the position at which the vessel's speed is reduced for the approach to port
  4. It is the position at which the vessel must begin the turn so that the track settles onto the next leg without overshooting the safe-water corridor Correct answer.

Explanation

The wheel-over point is calculated from the vessel's advance and transfer at the planned speed and rudder angle, and it is marked so that the turn starts early enough to settle onto the next course. Allowing for the turning circle keeps the vessel inside the safe-water corridor drawn around the waypoint. If the turn is begun late, the vessel may swing outside the corridor and close a hazard.

Question 23Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

A vessel's position is plotted on a chart whose compass rose shows variation 4° West in 2020, decreasing 6' annually. What variation should be applied in 2025?

  1. 3°30' West Correct answer.
  2. 4°30' West
  3. 3°30' East
  4. 4°00' West

Explanation

The annual change of 6 minutes over five years amounts to 30 minutes of decrease. A decreasing westerly variation becomes smaller, so 4°00' West becomes 3°30' West. The sign convention must be watched carefully, because a decreasing easterly variation would move toward zero and then become westerly.

Question 24Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

What is the principal reason for preferring a three-bearing fix over a two-bearing fix when the objects are well spread?

  1. The third line reveals the presence of a constant error through the size of the cocked hat Correct answer.
  2. Three bearings eliminate the effect of current on the vessel's position
  3. Three bearings remove the need to correct for compass deviation
  4. Three bearings are quicker to observe than two

Explanation

When three position lines fail to meet at a single point they form a cocked hat, and a systematic error such as an uncorrected compass error or a wrongly identified object causes a characteristic displacement of the lines. The size and shape of the cocked hat therefore give a check on the reliability of the fix. A two-bearing fix gives no such internal check because the lines always cross at one point.

Question 25Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

On a chart, what does a magenta arc with a labelled distance, centred on a light, represent?

  1. The boundary of a traffic separation scheme
  2. The sector in which the light is obscured
  3. The nominal range of the light at which it becomes visible in clear weather Correct answer.
  4. The limit of the charted anchorage

Explanation

Arcs drawn around a light show the nominal range and allow the navigator to judge when the light should be sighted or lost in clear weather. They are drawn in magenta and are a navigational aid rather than a boundary of any regulated area. The actual sighting range may differ because of atmospheric conditions and the observer's height of eye.

Question 26Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

On a Mercator chart, the compass rose indicates variation 6° West in 2015, decreasing 4' annually. In 2025, what is the variation to apply when converting between true and magnetic bearings?

  1. 6°40' West
  2. 6°00' West
  3. 5°20' East
  4. 5°20' West Correct answer.

Explanation

Annual change is applied for the elapsed years: 10 years × 4' = 40' of decrease. Subtracting 40' from 6°00' West gives 5°20' West, and because the value remains westerly the direction is unchanged. The resulting variation is applied magnetic-to-true by subtracting westerly variation.

Question 27Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

A vessel is in a position where the charted depth is 9.0 metres and the chart datum is Mean Lower Low Water. If the height of tide at that time is 2.4 metres, what depth of water should the echo sounder be expected to indicate, ignoring any transducer offset?

  1. 9.0 metres
  2. 2.4 metres
  3. 11.4 metres Correct answer.
  4. 6.6 metres

Explanation

Charted depths are referenced to chart datum, which is close to the lowest predictable tide, so the actual depth of water is the charted depth plus the height of tide above datum. Adding 9.0 m and 2.4 m gives 11.4 m. This assumes the echo sounder is calibrated and the transducer is at the waterline, which is why a draught or offset correction is normally applied separately.

Question 28Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

A vessel is making good a course of 000° True at 12 knots. A current sets 090° True at 3 knots. What is the vessel's speed made good over the ground?

  1. 9.0 knots
  2. 12.0 knots
  3. 15.0 knots
  4. 12.4 knots Correct answer.

Explanation

Course and current are at right angles, so the vectors combine as the hypotenuse of a right triangle: the square root of (12² + 3²) equals the square root of 153, about 12.4 knots. The current does not simply add to or subtract from speed because it acts across the track rather than along it. The resulting ground track also lies slightly to starboard of 000° True.

Question 29Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

During a coastal passage at night with no reliable identifiable lights, which position-fixing method gives the most dependable fix?

  1. A single bearing of a distant lighthouse
  2. Radar ranges and bearings of two or more well-defined charted headlands Correct answer.
  3. Dead reckoning advanced from the last fix
  4. An estimated position from the log and gyrocompass alone

Explanation

Radar does not depend on seeing lights or landmarks visually, so ranges and bearings of well-defined charted features such as headlands can be measured in darkness or poor visibility. Two or more such position lines, ideally with a good angle of cut, produce a reliable fix. Visual, dead reckoning and estimated positions all degrade as time and distance from the last known position increase.

Question 30Navigation: terrestrial and coastal navigation, position fixing, passage planning, and chartwork

A vessel is steering 090° True at 15 knots. A light is observed bearing 045° True at a range of 4 nautical miles. The vessel maintains course and speed. What is the closest point of approach of the light to the vessel, assuming no current?

  1. 2.8 nautical miles Correct answer.
  2. 4.0 nautical miles
  3. 1.4 nautical miles
  4. 2.0 nautical miles

Explanation

The relative bearing of the light is 45° to port of the heading, so the bearing of the vessel from the light is 225° True. The closest point of approach equals the range multiplied by the sine of the relative bearing: 4 × sin 45° = 2.83 nautical miles. Because the light is on the port bow and the vessel holds her course, the light will pass down the port side at that distance.

Question 31COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

Under the COLREGs, a power-driven vessel underway at night shows a forward masthead light, a second masthead light abaft of and higher than the forward one, and sidelights. What other light must she show when she is more than 50 metres in length?

  1. Two all-round red lights in a vertical line
  2. A sternlight and an all-round red light over a white light
  3. A sternlight and, when towing, a yellow towing light above it
  4. A sternlight only Correct answer.

Explanation

Rule 23 requires a power-driven vessel underway to exhibit sidelights, masthead lights and a sternlight. A second masthead light is required for vessels of 50 metres or more in length, but the sternlight requirement applies to all power-driven vessels underway. The additional combinations listed belong to other statuses such as towing or not under command.

Question 32COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

You are in a narrow channel and wish to overtake a vessel ahead. Which sound signal do you sound to indicate your intention to overtake on the other vessel's starboard side?

  1. Two prolonged blasts followed by one short blast
  2. One prolonged blast followed by one short blast
  3. One short blast
  4. Two prolonged blasts followed by two short blasts Correct answer.

Explanation

Rule 34(c) prescribes the overtaking signals in a narrow channel: two prolonged blasts followed by one short blast means 'I intend to overtake you on your starboard side', and two prolonged followed by two short means the port side. The overtaken vessel answers with one prolonged, one short, one prolonged, one short blast if she agrees. One short blast is a course-alteration signal to starboard under Rule 34(a).

Question 33COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

In restricted visibility, a power-driven vessel making way through the water shall sound which signal at intervals of not more than two minutes?

  1. Three blasts, one prolonged followed by two short
  2. Two prolonged blasts
  3. One prolonged blast followed by two short blasts
  4. One prolonged blast Correct answer.

Explanation

Rule 35(a) requires a power-driven vessel making way through the water in restricted visibility to sound one prolonged blast at intervals of not more than two minutes. A vessel stopped but not anchored sounds two prolonged blasts with an interval between them. The prolonged-plus-two-short signal identifies a vessel restricted in her ability to manoeuvre, not a normal power-driven vessel.

Question 34COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

Two power-driven vessels are crossing so as to involve risk of collision, and the bearing between them is not changing. Which vessel is the give-way vessel?

  1. The vessel that has the other on her own port side
  2. The vessel that has the other on her own starboard side Correct answer.
  3. The vessel to windward
  4. The faster vessel

Explanation

Rule 15 provides that when two power-driven vessels are crossing so as to involve risk of collision, the vessel which has the other on her own starboard side shall keep out of the way. The stand-on vessel must maintain her course and speed. Windward and speed are irrelevant to the crossing rule.

Question 35COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

A vessel is engaged in trawling and is making way through the water. Which lights does she exhibit at night?

  1. Only sidelights and a sternlight
  2. A green over white all-round light and a sternlight
  3. A red over white all-round light, sidelights and a sternlight
  4. Two all-round lights in a vertical line, the upper red and the lower white, plus sidelights and a sternlight Correct answer.

Explanation

Rule 26(b) requires a vessel engaged in trawling to show two all-round lights in a vertical line, the upper being green and the lower white, and, when making way, sidelights and a sternlight. The red-over-white pair identifies a vessel fishing other than trawling. The green-over-white pair is the trawler's identity signal when not making way.

Question 36COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

Which shape must a vessel at anchor display by day in the circumstances prescribed by the COLREGs?

  1. One black cylinder
  2. One black ball in the fore part of the vessel Correct answer.
  3. One black cone, apex upwards
  4. Two black balls in a vertical line

Explanation

Rule 30(a) requires a vessel at anchor to exhibit where it can best be seen one black ball in the fore part of the vessel. A vessel aground shows three black balls in a vertical line. The cone and cylinder shapes relate to other statuses such as sailing vessels under power or vessels constrained by draught.

Question 37COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

A vessel is engaged in fishing with nets and is not making way through the water. Which all-round lights does she exhibit?

  1. Two all-round lights in a vertical line, the upper green and the lower white
  2. Three all-round red lights in a vertical line
  3. An all-round red light over an all-round green light
  4. Two all-round lights in a vertical line, the upper red and the lower white Correct answer.

Explanation

Rule 26(c) provides that a vessel engaged in fishing, other than trawling, shall exhibit two all-round lights in a vertical line, the upper being red and the lower white. When making way she also shows sidelights and a sternlight. The green-over-white pair belongs to a trawler, and three red lights indicate a vessel aground.

Question 38COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

Which statement correctly describes the light or shape a vessel constrained by her draught may exhibit?

  1. Two black cones, points together, in a vertical line
  2. A black cylinder exhibited where it can best be seen Correct answer.
  3. Three all-round red lights in a vertical line
  4. A black ball in the fore part of the vessel

Explanation

Rule 28 provides that a vessel constrained by her draught may exhibit, in addition to the lights for a power-driven vessel, three all-round red lights in a vertical line, or a cylinder, where these can best be seen. The cylinder is the daytime shape; the three red lights are the night signal. The black ball marks an anchored vessel.

Question 39COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

A sailing vessel is proceeding under power in a narrow channel during daylight. What shape must she exhibit?

  1. A black diamond
  2. A black ball
  3. A black cone with apex downwards Correct answer.
  4. A black cylinder

Explanation

Rule 25(e) requires a vessel proceeding under sail and also being propelled by machinery to exhibit forward where it can best be seen a conical shape with apex downwards. At night she shows the appropriate lights for a power-driven vessel. The ball, diamond and cylinder mark other statuses.

Question 40COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

Two power-driven vessels are meeting head-on or nearly head-on so as to involve risk of collision. Which action does Rule 14 require?

  1. Each shall alter course to port so that they pass starboard side to starboard
  2. The vessel to starboard shall hold course while the other gives way
  3. Each shall alter course to starboard so that they pass port side to port side Correct answer.
  4. Both vessels shall stop their engines and drift

Explanation

Rule 14 requires each vessel in a head-on situation to alter course to starboard so that each passes on the port side of the other. Neither vessel is a stand-on vessel in this situation, so both must act. Stopping is not the prescribed response.

Question 41COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

A power-driven vessel is overtaking another power-driven vessel. Which statement correctly states the obligation of the overtaking vessel?

  1. The overtaken vessel must give way because she is ahead
  2. Both vessels must alter course to starboard simultaneously
  3. The overtaking vessel has right of way and may hold her course
  4. The overtaking vessel must keep out of the way until finally past and clear Correct answer.

Explanation

Rule 13 provides that any vessel overtaking another shall keep out of the way of the vessel being overtaken, and this duty continues until she is finally past and clear. The overtaken vessel maintains her course and speed. The term 'right of way' is not used in the COLREGs; the overtaking vessel is the give-way vessel.

Question 42COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

You are the stand-on vessel in a crossing situation with a power-driven vessel. The give-way vessel is not taking appropriate action to avoid collision. What does Rule 17 permit you to do?

  1. You must alter course to port to pass astern of the other vessel
  2. You must sound five short and rapid blasts and hold your course
  3. You may take action to avoid collision by your manoeuvre alone as soon as you become aware of the situation Correct answer.
  4. You must maintain course and speed until the other vessel has passed

Explanation

Rule 17(a)(ii) provides that the stand-on vessel may take action to avoid collision by her manoeuvre alone as soon as it becomes apparent that the give-way vessel is not taking appropriate action. When action is taken, it should if possible avoid altering course to port for a vessel on her own port side. The stand-on vessel is not obliged to hold course when collision is imminent.

Question 43COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

Which of the following describes the light or shape requirement for a vessel not under command at night?

  1. Two all-round red lights in a vertical line, and if making way, sidelights and a sternlight Correct answer.
  2. Three all-round red lights in a vertical line
  3. Two all-round red lights in a vertical line only, regardless of whether she is making way
  4. An all-round red light over an all-round white light

Explanation

Rule 27(a) requires a vessel not under command to exhibit two all-round red lights in a vertical line, and if making way, sidelights and a sternlight. A vessel not making way shows only the two red lights. Three red lights indicate a vessel constrained by her draught, and red over white is a fishing signal.

Question 44COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

A vessel is at anchor in restricted visibility. Which sound signal does Rule 35 require her to make?

  1. Two prolonged blasts at intervals of not more than two minutes
  2. Rapid ringing of the bell for about five seconds at intervals of not more than one minute Correct answer.
  3. One prolonged blast at intervals of not more than two minutes
  4. Three separate and distinct strokes on the bell followed by a rapid ringing

Explanation

Rule 35(g) requires a vessel at anchor in restricted visibility to ring the bell rapidly for about five seconds at intervals of not more than one minute. A vessel of 100 metres or more in length also sounds one short blast before and one after the ringing. The prolonged-blast signals belong to vessels making way or stopped.

Question 45COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

What does a vessel sound to indicate that she is in doubt as to the intentions or actions of another vessel, or is taking action to avoid collision?

  1. One short blast followed by one prolonged blast
  2. Two prolonged blasts
  3. Three short blasts
  4. At least five short and rapid blasts Correct answer.

Explanation

Rule 34(d) provides that when a vessel is in doubt as to the intention of another or is taking action to avoid collision, she shall sound at least five short and rapid blasts on the whistle. This is a warning signal, not a manoeuvring signal. Three short blasts indicate that engines are operating astern.

Question 46COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

A vessel is engaged in mineclearance operations. How are her lights and shapes affected by the danger she presents?

  1. She shows the lights and shapes for a power-driven vessel and no special marks
  2. She shows three all-round green lights in a vertical line by night and three black balls in a vertical line by day
  3. She shows the lights and shapes for a vessel restricted in her ability to manoeuvre only
  4. She shows the lights and shapes for a vessel restricted in her ability to manoeuvre plus three all-round green lights and three black balls in a vertical line Correct answer.

Explanation

Rule 27(f) provides that a vessel engaged in mineclearance operations shall, in addition to the lights and shapes prescribed for a vessel restricted in her ability to manoeuvre, exhibit three all-round green lights in a vertical line or three black balls in a vertical line. These marks warn others of the extreme danger. The restricted-in-ability lights alone do not convey the mineclearance hazard.

Question 47COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

Two sailing vessels are approaching one another so as to involve risk of collision, with the wind on different sides. Which vessel must keep out of the way?

  1. The vessel which has the wind on her starboard side
  2. The vessel to leeward
  3. The vessel which is closer to the other
  4. The vessel which has the wind on her port side Correct answer.

Explanation

Rule 12(a)(i) provides that when two sailing vessels are approaching with the wind on different sides, the vessel which has the wind on her port side shall keep out of the way of the other. This is the basic windward/leeward test in sailing-vessel encounters. Proximity alone does not determine the give-way vessel.

Question 48COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

A vessel is showing three all-round red lights in a vertical line at night and a black cylinder by day. What does this indicate?

  1. A vessel engaged in mineclearance
  2. A vessel constrained by her draught Correct answer.
  3. A vessel aground
  4. A vessel not under command

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, in addition to the lights for a power-driven vessel. A vessel not under command shows two red lights and two black balls. A vessel aground shows three black balls, and a mineclearance vessel shows three green lights or balls.

Question 49COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

In a narrow channel, a vessel proceeding along the course of the channel must keep as near to the outer limit which lies on which side of her?

  1. The side away from the nearest bank
  2. Either side, at her discretion
  3. Her port side
  4. Her starboard side Correct answer.

Explanation

Rule 9(a) requires a vessel proceeding along the course of a narrow channel or fairway to keep as near to the outer limit of the channel or fairway which lies on her starboard side as is safe and practicable. This keeps opposing traffic separated. Port-side keeping would conflict with the convention.

Question 50COLREGs: steering, sailing rules, lights, shapes, sound and light signals, and conduct of vessels

A vessel is engaged in a towing operation which severely restricts her ability to deviate from her course. Which additional lights does she show when towing at night?

  1. Two masthead lights in a vertical line and a sternlight only
  2. A single masthead light and a yellow towing light
  3. Two all-round red lights in a vertical line and a sternlight
  4. Three masthead lights in a vertical line, sidelights, a sternlight and a yellow towing light in a vertical line above the sternlight Correct answer.

Explanation

Rule 24(a) requires a power-driven vessel when towing to exhibit two masthead lights in a vertical line, or three when the length of the tow exceeds 200 metres, in addition to sidelights and a sternlight. A yellow towing light in a vertical line above the sternlight is also required. When the tow exceeds 200 metres, the towed vessel shows an additional masthead light.