I85PREP
⌘ K
MAJ OOW Deck Exam study materials
MAJ OOW Deck Exam study resources

MAJ OOW Deck Exam practice questions

One question at a time. Build your MAJ OOW Deck Exam understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Navigation and Position Fixing

On a nautical chart, a light is described as 'Fl(3) R 10s 24m 15M'. What does the '15M' represent?

  1. The geographic range of the light as limited by the curvature of the earth
  2. The nominal range of the light in nautical miles Correct answer.
  3. The height of the light above mean high water in metres
  4. The distance at which the light first becomes visible over the horizon

Explanation

In a chart light characteristic, the final figure followed by 'M' is the nominal range, the distance in nautical miles at which the light reaches a stated luminous intensity under a meteorological visibility of 10 nautical miles. It is a property of the light's intensity, not of the observer's height of eye. Geographic range, by contrast, depends on the heights of the light and the observer.

Question 2Navigation and Position Fixing

A vessel is steering 000° (T) at 12 knots. A fix taken at 0800 places the vessel on a bearing of 090° (T), 6 nautical miles from a headland. What is the vessel's CPA to the headland if course and speed are maintained?

  1. 3.0 nautical miles
  2. 6.0 nautical miles
  3. 0 nautical miles
  4. 5.2 nautical miles Correct answer.

Explanation

With the vessel due west of the headland steering due north, the closest point of approach is found by dropping a perpendicular from the headland to the course line. The perpendicular distance is the original bearing offset: 6 × sin(30°) is not applicable here, but the geometry gives a CPA of 6 × cos(30°) ≈ 5.2 nautical miles because the bearing is 90° and the course 000°, so the perpendicular is 6 × cos(30°). Careful plotting on a manoeuvring board confirms approximately 5.2 nautical miles.

Question 3Navigation and Position Fixing

Which statement correctly describes the difference between true bearing and relative bearing as displayed on a vessel's radar?

  1. True bearing and relative bearing are identical when the vessel is on a cardinal heading
  2. True bearing is measured from the ship's heading, while relative bearing is measured from north
  3. True bearing is measured clockwise from north, while relative bearing is measured clockwise from the ship's heading Correct answer.
  4. Relative bearing is always expressed in degrees from 000° to 180° on either side of the bow

Explanation

True bearing is referenced to true north and increases clockwise through 360°. Relative bearing is referenced to the vessel's heading line and also increases clockwise, so adding heading to relative bearing (modulo 360°) gives the true bearing. Radar displays can present either, and confusing them is a common source of plotting error.

Question 4Navigation and Position Fixing

A three-point fix is taken using two charted objects and a third whose bearing is doubtful. Which action best preserves the reliability of the fix?

  1. Plot all three and accept the centre of the cocked hat as the position
  2. Use only the two reliable bearings and treat the fix as a two-bearing fix with a cocked hat of uncertainty Correct answer.
  3. Average the three bearing lines and plot the mean position
  4. Discard the fix entirely and rely on dead reckoning until a new object is sighted

Explanation

A cocked hat indicates systematic error or a misidentified object; accepting its centre can place the vessel well away from the true position. When one object is known to be unreliable, the sound practice is to plot only the trusted bearings and treat the resulting intersection as a two-bearing fix, with the residual error estimated. Averaging or centring the triangle gives false confidence.

Question 5Navigation and Position Fixing

On a Mercator chart, the scale of latitude is:

  1. Constant everywhere on the chart
  2. Expanded progressively towards the poles Correct answer.
  3. Equal to the scale of longitude at all latitudes
  4. Compressed progressively towards the poles

Explanation

The Mercator projection stretches the meridians so that rhumb lines plot as straight lines. To preserve shape, the latitude scale must expand with increasing latitude, which is why a minute of latitude represents a larger distance on the chart near the poles. The scale of longitude is constant along any parallel, but the two scales are equal only at the equator.

Question 6Navigation and Position Fixing

A vessel's log reads 124.6 at 1200 and 137.2 at 1600. What is the average speed through the water over the period?

  1. 2.10 knots
  2. 1.89 knots
  3. 3.15 knots Correct answer.
  4. 12.6 knots

Explanation

Distance run is 137.2 − 124.6 = 12.6 nautical miles over 4 hours, giving 12.6 ÷ 4 = 3.15 knots. Log distance measures speed through the water, so this is speed through the water, not speed over the ground. The calculation is a straightforward time-speed-distance division.

Question 7Navigation and Position Fixing

Which of the following is the primary purpose of a dead reckoning (DR) position on a passage plan?

  1. To plot the vessel's intended track over the ground
  2. To provide an approximate position from course and speed alone when no fix is available Correct answer.
  3. To indicate the vessel's position corrected for leeway and current
  4. To record the position of the vessel at each course alteration

Explanation

Dead reckoning advances the last known position using courses steered and speed through the water, without allowing for current, leeway or other external effects. It is the baseline against which a fix is compared to reveal the set and drift. An estimated position (EP) is the DR position corrected for these effects.

Question 8Navigation and Position Fixing

A vessel is in the northern hemisphere and observes Polaris bearing 000° (T) at an altitude of 38°. Which statement is correct?

  1. The vessel's longitude is approximately 38°E
  2. The vessel's latitude is approximately 38°N Correct answer.
  3. The vessel's latitude cannot be determined from Polaris alone
  4. The vessel's latitude is approximately 52°N

Explanation

In the northern hemisphere, the altitude of Polaris above the horizon is approximately equal to the observer's latitude, subject to a small correction for the star's offset from the pole. An observed altitude of 38° therefore indicates a latitude close to 38°N. Polaris gives no longitude information.

Question 9Navigation and Position Fixing

A vessel on course 045° (T) at 15 knots experiences a current setting 135° (T) at 3 knots. What is the approximate course and speed made good?

  1. Course 090° (T), speed 18.0 knots
  2. Course 034° (T), speed 17.2 knots
  3. Course 056° (T), speed 12.4 knots Correct answer.
  4. Course 045° (T), speed 15.0 knots

Explanation

The current sets at right angles to the course, so the resultant is the vector sum of a 15-knot northeasterly course and a 3-knot southeasterly set. The resultant speed is √(15² + 3²) ≈ 15.3 knots, but because the current opposes part of the northward component, the made-good speed is reduced to about 12.4 knots on a course of roughly 056° (T). The exact values come from resolving components: north 15cos45 − 3cos45 and east 15sin45 + 3sin45.

Question 10Navigation and Position Fixing

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

  1. A transfer along the vessel's course and speed made good between observations Correct answer.
  2. A correction for the change in the object's bearing rate
  3. A reduction for the dip of the horizon
  4. A rotation to the vessel's heading at the time of the second observation

Explanation

A running fix advances the earlier position line along the vessel's track by the distance run between observations, using course and speed made good. The intersection of the advanced line with the later bearing gives the fix. This technique is useful when only one object is available for observation.

Question 11Navigation and Position Fixing

A position is given as latitude 34°15.6'S, longitude 018°42.3'E. What is the position in degrees, minutes and seconds of arc?

  1. 34°15'36"S, 018°42'18"E Correct answer.
  2. 34°16'56"S, 018°43'23"E
  3. 34°15'06"S, 018°42'03"E
  4. 34°15'60"S, 018°42'30"E

Explanation

Decimal minutes are converted to seconds by multiplying the decimal part by 60. For latitude, 0.6 minute × 60 = 36 seconds, giving 15'36". For longitude, 0.3 minute × 60 = 18 seconds, giving 42'18". The resulting position is 34°15'36"S, 018°42'18"E.

Question 12Navigation and Position Fixing

Which charted feature would you consult to identify a traffic separation scheme and its associated inshore traffic zone?

  1. The largest-scale harbour chart covering the approaches
  2. The tide tables for the nearest standard port
  3. The appropriate small-scale passage chart for the area Correct answer.
  4. The sailing directions for the region

Explanation

Traffic separation schemes and their inshore traffic zones are charted on the appropriate passage or coastal charts for the area, where the scheme boundaries, lanes and precautionary areas are shown. Harbour charts are usually too large in scale to cover the full scheme. Sailing directions describe the scheme in words but do not show its geometry.

Question 13Navigation and Position Fixing

A vessel's GPS receiver indicates a horizontal dilution of precision (HDOP) of 6. How should the watchkeeper treat the resulting position?

  1. As unusable and to be discarded entirely
  2. As a degraded fix requiring cross-checking against other position sources Correct answer.
  3. As a high-accuracy fix suitable for pilotage in confined waters
  4. As equivalent to a visual fix because GPS is always more accurate

Explanation

HDOP expresses the geometric quality of the satellite constellation; higher values indicate poorer geometry and greater position uncertainty. An HDOP of 6 is relatively high and the fix should be treated as degraded and cross-checked with visual, radar or other means. It is not automatically unusable, but it should not be relied on alone in confined waters.

Question 14Navigation and Position Fixing

What is the purpose of the 'dip' correction when reducing a sextant altitude of the sun?

  1. To allow for the semi-diameter of the sun
  2. To allow for the height of the observer's eye above the sea horizon Correct answer.
  3. To correct for the parallax of the sun
  4. To correct for refraction in the earth's atmosphere

Explanation

Dip is the angle between the sensible horizon at the observer's eye and the true horizontal, and it increases with height of eye. It is subtracted from the sextant altitude to reduce the observation to the true horizon. Refraction, parallax and semi-diameter are separate corrections applied afterwards.

Question 15Navigation and Position Fixing

A vessel is steering 270° (T). A light is observed bearing 315° (T). What is the relative bearing of the light?

  1. 045° on the port bow
  2. 045° on the starboard bow Correct answer.
  3. 315° on the port quarter
  4. 090° on the starboard beam

Explanation

Relative bearing is true bearing minus heading: 315° − 270° = 045°. A relative bearing of 045° lies on the starboard side, 45° forward of the beam, i.e. on the starboard bow. This conversion is used constantly when relating visual or radar observations to the ship's heading.

Question 16Navigation and Position Fixing

Which statement about the use of a single position line is correct?

  1. A single position line is only valid for celestial observations
  2. A single position line indicates that the vessel lies somewhere along that line Correct answer.
  3. A single position line defines the vessel's position exactly
  4. A single position line must always run parallel to the vessel's course

Explanation

One position line constrains the vessel to a locus of points but does not fix a unique position; a second, independent line or a known distance is needed. The line can be a bearing, a range arc or a celestial position line. Its value is in confirming or correcting the vessel's position along that locus.

Question 17Navigation and Position Fixing

A vessel is on a course of 090° (T) making 10 knots. A radar target is observed bearing 090° (T) at 8 miles and, six minutes later, bearing 090° (T) at 7 miles. What is the target's true course and speed?

  1. Course 270° (T), speed 10 knots Correct answer.
  2. Course 270° (T), speed 20 knots
  3. Course 090° (T), speed 10 knots
  4. Course 090° (T), speed 20 knots

Explanation

The target remains on the same bearing while the range decreases, so it lies directly ahead on the vessel's course line. The range closes 1 mile in 6 minutes, a relative speed of 10 knots. Because the target's bearing does not change, its true course is reciprocal to the vessel's, i.e. 270° (T), at 10 knots, giving a closing rate of 20 knots, not 10. Rechecking: relative speed is 10 knots, so target speed equals 20 − 10 = 10 knots on 270° (T).

Question 18Navigation and Position Fixing

Which of the following best defines 'set' and 'drift' in tidal stream terminology?

  1. Set is the direction towards which the stream flows, and drift is its rate in knots Correct answer.
  2. Set is the rate in knots, and drift is the direction of flow
  3. Set is the rise of tide, and drift is the fall of tide
  4. Set is the direction of the wind, and drift is the resulting leeway

Explanation

The set of a tidal stream is the direction towards which the water moves, usually expressed as a true bearing. The drift is the speed of the stream, expressed in knots. These terms are used when plotting the tidal vector on a course-to-steer or ground-track construction.

Question 19Navigation and Position Fixing

A vessel's echo sounder reads 42 metres. The transducer is 2 metres below the waterline. What is the depth of water below the keel if the keel is 5 metres below the waterline?

  1. 37 metres
  2. 35 metres Correct answer.
  3. 47 metres
  4. 39 metres

Explanation

The echo sounder measures from the transducer to the seabed, so the depth below the waterline is 42 + 2 = 44 metres. The depth below the keel is then 44 − 5 = 39 metres. Care must be taken to establish whether the sounder is calibrated to show depth below the keel or below the transducer.

Question 20Navigation and Position Fixing

When using a transit (two objects in line) to check a vessel's position, which condition makes the observation most reliable?

  1. The two objects are of equal height above sea level
  2. The two objects are widely separated and close to the vessel Correct answer.
  3. The two objects are lit and visible by night
  4. The two objects are close together and far from the vessel

Explanation

The accuracy of a transit depends on the angular separation of the objects as seen from the vessel. Widely separated objects close to the vessel give a large angle and a well-defined line; objects close together far away give a poorly defined line. The transit defines a line of position, so a second line is needed for a fix.

Question 21Navigation and Position Fixing

On a chart, a magenta arc with the annotation 'RACON' indicates:

  1. A buoy with a radar reflector
  2. A radio direction-finding station
  3. A radar beacon that transmits a characteristic signal for identification Correct answer.
  4. A sector light with a red sector

Explanation

RACON denotes a radar beacon, usually mounted on a navigation mark, which responds to a radar interrogation with a characteristic Morse signal on the radar display. This allows positive identification of the mark in poor visibility. It is not a radio direction-finding station or a reflector.

Question 22Navigation and Position Fixing

A vessel's gyrocompass has a known error of 2°E. A bearing taken of a lighthouse reads 134° by gyro. What is the true bearing?

  1. 132° (T)
  2. 136° (T) Correct answer.
  3. 134° (T)
  4. 138° (T)

Explanation

If the gyro reads east of true, the true bearing is the gyro bearing plus the easterly error: 134° + 2° = 136° (T). The mnemonic 'compass least, error east' applies to magnetic compass deviation, but for gyro error the correction is added when the error is east. Applying the correction consistently is essential before plotting.

Question 23Navigation and Position Fixing

Which statement correctly describes the line of position obtained from a celestial observation of a star?

  1. It is a small circle centred on the star's geographic position
  2. It is a straight line on the chart regardless of the projection used
  3. It is a circle of equal altitude, plotted as a straight line over short distances Correct answer.
  4. It is a great circle passing through the observer's zenith

Explanation

A celestial observation defines a circle of equal altitude centred on the body's geographic position (GP). Over the short distances used in practical navigation, this circle can be approximated by a straight line, the intercept method. The line is not a great circle through the zenith, and it is not a small circle centred on the star itself.

Question 24Navigation and Position Fixing

A vessel is approaching a harbour and the chart shows a leading line marked 'Ldg Lts 090°'. The vessel is steering 095° (T) and the leading marks appear open. Which action is correct?

  1. Alter course to port until the marks are in line Correct answer.
  2. Reduce speed and continue on 095° (T) while monitoring the echo sounder
  3. Alter course to starboard until the marks are in line
  4. Maintain course and speed because the leading line is advisory only

Explanation

If the vessel is steering east-south-east of the leading line of 090°, it lies to the south of the line. To bring the marks into line, the vessel must steer towards the line, which requires a turn to port onto approximately 090° (T). Leading lines are precise position lines and should be followed when navigating the approach.

Question 25Navigation and Position Fixing

What is the effect of a chart's horizontal datum on GPS position plotting?

  1. The datum affects only the latitude scale
  2. GPS and charts always use WGS84, so no adjustment is needed
  3. The datum affects only depths, not positions
  4. A datum shift must be applied if the chart uses a datum other than WGS84 Correct answer.

Explanation

GPS positions are referenced to WGS84, while older charts may use a different horizontal datum such as a local astro datum. If the datums differ, a position offset can occur and must be corrected, often by using the datum shift note or the receiver's chart datum setting. Ignoring the difference can place the vessel outside the intended channel.

Question 26Navigation and Position Fixing

A vessel's echo sounder displays a depth of 36 metres below the keel. The charted depth at that position is 34 metres. Which statement best explains the difference between the two readings?

  1. The charted depth includes an allowance for the height of tide, while the echo sounder does not.
  2. The charted depth is measured below the keel, while the echo sounder displays depth below the waterline.
  3. The charted depth is reduced to chart datum, while the echo sounder reads the actual depth below the keel at that moment. Correct answer.
  4. The echo sounder and the chart both refer to the same datum, so the two-metre difference indicates a receiver calibration error.

Explanation

Charted soundings are reduced to chart datum, which is normally close to lowest astronomical tide, so they represent the least depth expected. An echo sounder measures the real instantaneous depth below the transducer or keel, which includes the height of tide above datum. The two figures therefore differ by the height of tide plus any transducer offset, not by a fault or a differing reference line.

Question 27Navigation and Position Fixing

A vessel's true course is 060° (T) at 12 knots. A current sets 150° (T) at 4 knots. Using a one-hour vector triangle, what is the approximate course made good and speed made good?

  1. Course 045° (T), speed 16.0 knots
  2. Course 075° (T), speed 14.5 knots
  3. Course 068° (T), speed 15.1 knots Correct answer.
  4. Course 090° (T), speed 12.6 knots

Explanation

Resolve the two one-hour vectors into components. The course vector gives 12 sin 60° = 10.39 east and 12 cos 60° = 6.00 north; the current vector gives 4 sin 150° = 2.00 east and 4 cos 150° = -3.46 north. The resultant is 12.39 east and 2.54 north, giving a course made good of about 078° (T) and a speed of about 12.6 knots.

Question 28Navigation and Position Fixing

A vessel's chronometer reads 09:14:22 and has a known error of 2 minutes 08 seconds slow. What is the correct UTC at that instant?

  1. 09:14:22
  2. 09:12:14
  3. 09:16:14
  4. 09:16:30 Correct answer.

Explanation

A chronometer that is slow shows a time earlier than UTC, so the error must be added to the reading. Adding 2 minutes 08 seconds to 09:14:22 gives 09:16:30 UTC. Chronometer error is always applied with its sign: add when slow, subtract when fast.

Question 29Navigation and Position Fixing

A vessel's position is fixed by two position lines that cross at an angle of 30°. What is the principal consequence for the accuracy of the fix?

  1. The fix is unaffected by the crossing angle, since accuracy depends only on the quality of the observations.
  2. The fix is unreliable only if the two position lines come from the same object at different times.
  3. The fix is unreliable because a small error in either position line produces a large displacement of the intersection point. Correct answer.
  4. The fix is more accurate than a 90° cut because the two lines intersect over a longer baseline.

Explanation

The angle of cut determines how observation errors are magnified at the intersection. When position lines cross at a small angle, small lateral errors translate into a large shift of the plotted fix along the bisector. A cut close to 90° gives the strongest fix, so a 30° intersection should be avoided or supplemented with a third line.

Question 30Navigation and Position Fixing

A vessel's satellite compass fails while on passage and the master must rely on the magnetic compass for steering. Which set of corrections must be applied to convert a compass bearing into a true bearing?

  1. Deviation applied to the compass bearing to give magnetic, then variation applied to give true Correct answer.
  2. Variation applied to the compass bearing to give magnetic, then deviation applied to give true
  3. Deviation, variation, and the vessel's angle of heel
  4. Variation only, since deviation is a property of the compass installation

Explanation

The sequence from compass to true is compass, magnetic, true. Deviation, the error caused by the vessel's own magnetic field, is applied first to obtain the magnetic bearing; variation, the difference between magnetic and true north at that locality, is then applied. Reversing the order gives an incorrect result because deviation is defined relative to magnetic north.

Question 31Collision Regulations and Safe Navigation

Under COLREG Rule 13, when does an overtaking situation exist between two power-driven vessels?

  1. When one vessel is coming up with another from a direction more than 22.5 degrees abaft her beam Correct answer.
  2. When one vessel is approaching another from any direction ahead of the beam
  3. When one vessel is approaching another from a direction more than 45 degrees abaft her beam
  4. When both vessels are proceeding on parallel courses at the same speed

Explanation

Rule 13 defines overtaking as coming up with another vessel from a direction more than 22.5 degrees abaft her beam, meaning the overtaking vessel is unable to see either sidelight of the other. The overtaking vessel must keep clear until finally past and clear, and any subsequent change of bearing does not make her a crossing vessel.

Question 32Collision Regulations and Safe Navigation

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

  1. The vessel nearer the channel edge sounds one short blast and holds course
  2. The vessel with more sea room maintains course and speed
  3. The vessel with the other on her port side alters to starboard
  4. Both vessels alter course to starboard and pass port to port Correct answer.

Explanation

Rule 14 requires each vessel to alter course to starboard so that they pass port to port, unless doubt exists whether a head-on situation exists. Both vessels share the obligation equally; neither may hold course expecting the other to give way.

Question 33Collision Regulations and Safe Navigation

A power-driven vessel underway in fog hears a fog signal of one prolonged blast from a vessel forward of her beam. What does this signal indicate?

  1. A vessel being towed
  2. A vessel not under command
  3. A power-driven vessel making way through the water Correct answer.
  4. A vessel at anchor warning of her position

Explanation

Rule 35 requires a power-driven vessel making way through the water to sound one prolonged blast at intervals of not more than two minutes in restricted visibility. Two prolonged blasts indicate a power-driven vessel underway but stopped and making no way.

Question 34Collision Regulations and Safe Navigation

Which light or shape must a vessel constrained by her draught exhibit in addition to those required for a power-driven vessel underway?

  1. A black cone with apex downwards
  2. A cylinder exhibited where it can best be seen Correct answer.
  3. Two black balls in a vertical line
  4. Three all-round red lights in a vertical line

Explanation

Rule 28 assigns the cylinder as the daytime shape for a vessel constrained by her draught, and at night she shows three all-round red lights in a vertical line in addition to the lights for a power-driven vessel underway. The cylinder is the shape that identifies her status in daylight.

Question 35Collision Regulations and Safe Navigation

In a narrow channel, a vessel intending to overtake another vessel must sound which signal to indicate her intention to pass 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. Two short blasts Correct answer.
  4. One short blast

Explanation

Rule 34 requires a vessel intending to overtake in a narrow channel to indicate her intention with two prolonged blasts followed by one short blast to pass on the starboard side, or two prolonged followed by two short blasts for the port side. The overtaken vessel then sounds the same signal if she agrees.

Question 36Collision Regulations and Safe Navigation

A power-driven vessel is crossing so as to involve risk of collision with a sailing vessel. Which statement correctly states the give-way obligation?

  1. The power-driven vessel gives way because the sailing vessel is the stand-on vessel Correct answer.
  2. Both vessels alter course to starboard simultaneously
  3. The sailing vessel gives way because she is more manoeuvrable
  4. The vessel with the wind on her port side gives way

Explanation

Rule 18 ranks vessels by their ability to keep clear, and a power-driven vessel underway must keep out of the way of a sailing vessel under sail. The sailing vessel is therefore the stand-on vessel and must maintain course and speed as required by Rule 17.

Question 37Collision Regulations and Safe Navigation

A vessel is drifting with her engines stopped and no way through the water, but she is not aground or at anchor. How is she described under the COLREGs?

  1. Not underway
  2. Making way
  3. At anchor
  4. Underway Correct answer.

Explanation

Rule 3 defines 'underway' as not being at anchor, made fast to the shore, or aground; it does not require the vessel to be moving through the water. A vessel drifting with engines stopped is therefore still underway but is not making way.

Question 38Collision Regulations and Safe Navigation

A vessel is approaching a bend in a narrow channel where she cannot see around the obstruction. What sound signal does Rule 34 require her to sound?

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

Explanation

Rule 34 requires any vessel approaching a bend or area of a narrow channel where other vessels may be obscured to sound one prolonged blast. Any approaching vessel within hearing around the bend must answer with one prolonged blast.

Question 39Collision Regulations and Safe Navigation

A vessel is engaged in pair trawling. Which lights must she exhibit at night?

  1. Two all-round lights in a vertical line, the upper red and the lower white, plus sidelights and sternlight Correct answer.
  2. Two all-round lights in a vertical line, the upper red and the lower white, plus a masthead light
  3. A single all-round green light over a white light
  4. A red light over a white light, with no sidelights required

Explanation

Rule 26 requires vessels engaged in pair trawling to exhibit two all-round lights in a vertical line, the upper red and the lower white, in the direction of the other vessel of the pair. Each vessel also shows sidelights and a sternlight when making way, but no masthead light.

Question 40Collision Regulations and Safe Navigation

A stand-on vessel in a crossing situation observes that the give-way vessel is not taking appropriate action. When does Rule 17 permit the stand-on vessel to take action?

  1. As soon as the stand-on vessel considers the give-way vessel is not keeping clear Correct answer.
  2. Never, until the give-way vessel has passed ahead
  3. Only when the vessels are so close that collision cannot be avoided by the give-way vessel alone
  4. Only after the give-way vessel sounds five short blasts

Explanation

Rule 17 allows the stand-on vessel to take action as soon as it becomes apparent that the give-way vessel is not taking appropriate action, and she may then act to avoid collision. Where circumstances permit she should avoid altering course to port for a vessel on her own port side.

Question 41Collision Regulations and Safe Navigation

What is the required vertical separation between the two masthead lights of a power-driven vessel of 50 metres or more in length?

  1. Not less than 6 metres Correct answer.
  2. Not less than 2 metres
  3. Not less than 4 metres
  4. Not less than 10 metres

Explanation

Rule 23 and Annex I require that on a power-driven vessel of 50 metres or more in length the forward masthead light be placed at least 6 metres above the after one. The vertical separation for vessels under 50 metres is at least 4.5 metres.

Question 42Collision Regulations and Safe Navigation

A vessel is at anchor in fog. What sound signal must she make to warn approaching vessels of her position?

  1. One prolonged blast 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. Two prolonged blasts at intervals of not more than two minutes
  4. Three strokes of the bell followed by rapid ringing

Explanation

Rule 35 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 at anchor may also sound one short, one prolonged and one short blast to give warning of her position.

Question 43Collision Regulations and Safe Navigation

Which of the following is a vessel restricted in her ability to manoeuvre for the purposes of the COLREGs?

  1. A vessel engaged in fishing with nets
  2. A vessel constrained by her draught
  3. A vessel not under command
  4. A vessel engaged in dredging and unable to keep out of the way of another vessel Correct answer.

Explanation

Rule 3 defines a vessel restricted in her ability to manoeuvre as one working that is unable to keep out of the way of another vessel, and lists dredging among the qualifying operations. A vessel constrained by her draught, a fishing vessel and a vessel not under command are separate categories with their own rules.

Question 44Collision Regulations and Safe Navigation

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

  1. The vessel with the larger sail area
  2. The vessel with the wind on her port side
  3. The vessel to windward
  4. The vessel with the wind on her starboard side Correct answer.

Explanation

Rule 12 provides that when two sailing vessels have the wind on different sides, the vessel with the wind on her port side must keep out of the way of the one with the wind on her starboard side. The port-side vessel is the give-way vessel and must take early and substantial action.

Question 45Collision Regulations and Safe Navigation

A power-driven vessel is underway at night and sees only a white light ahead. What should the officer of the watch conclude?

  1. A vessel is approaching from ahead and may be overtaken on either side Correct answer.
  2. The vessel is at anchor and need not be avoided
  3. A vessel is crossing from starboard and is the give-way vessel
  4. The vessel is a sailing vessel with the wind aft

Explanation

Seeing only a white light ahead indicates a sternlight of a vessel proceeding away, so the observing vessel is overtaking and must keep clear under Rule 13. The overtaken vessel shows no sidelights because she is being viewed from astern.

Question 46Collision Regulations and Safe Navigation

A power-driven vessel of 12 metres in length is underway at night. Which additional light may she exhibit instead of the masthead and sternlight combination?

  1. An all-round white light and sidelights Correct answer.
  2. Two all-round red lights in a vertical line
  3. A flashing white light at the masthead
  4. A single all-round green light

Explanation

Rule 23 permits a power-driven vessel of less than 12 metres in length to exhibit an all-round white light and sidelights in place of the masthead light and sternlight. The all-round white light must be visible all round the horizon and the sidelights must still be shown.

Question 47Collision Regulations and Safe Navigation

A vessel is engaged in a towing operation that severely limits her ability to deviate from her course. Which lights must she exhibit at night in addition to those for a power-driven vessel underway?

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

Explanation

Rule 27 requires a vessel restricted in her ability to manoeuvre, including one towing so as to severely limit her ability to deviate, to exhibit three all-round lights in a vertical line where they can best be seen. The upper and lower lights are red and the middle light is white.

Question 48Collision Regulations and Safe Navigation

A power-driven vessel is navigating in a traffic separation scheme. Which statement correctly describes her obligation when crossing a traffic lane?

  1. She may cross at any angle provided she keeps clear of other vessels
  2. She should cross only at the termination of the lane
  3. She must always cross on her starboard side of the lane
  4. She should cross on a heading as nearly as practicable at right angles to the general direction of traffic flow Correct answer.

Explanation

Rule 10 requires a vessel crossing traffic lanes to do so on a heading as nearly as practicable at right angles to the general direction of traffic flow. This minimises the time spent in the lane and reduces the risk of collision with through traffic.

Question 49Collision Regulations and Safe Navigation

A vessel is aground in fog. What sound signal must she make?

  1. Two prolonged blasts repeated at intervals
  2. Rapid ringing of the bell only
  3. One short blast followed by two prolonged blasts
  4. Three separate and distinct strokes of the bell before and after rapid ringing of the bell Correct answer.

Explanation

Rule 35 requires a vessel aground in restricted visibility to sound three separate and distinct strokes of the bell before and after the rapid ringing of the bell. She may also sound the appropriate signal on the gong where required by her length.

Question 50Collision Regulations and Safe Navigation

Two power-driven vessels are crossing with risk of collision, and the give-way vessel is on the stand-on vessel's starboard side. What must the give-way vessel do?

  1. Sound two short blasts and hold her course
  2. Keep out of the way and avoid crossing ahead of the stand-on vessel Correct answer.
  3. Alter course to port to pass astern
  4. Maintain course and speed so the stand-on vessel can manoeuvre

Explanation

Rule 15 requires the vessel that has the other on her own starboard side to keep out of the way, and Rule 16 requires her to take early and substantial action. Where possible she should avoid crossing ahead of the stand-on vessel.