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Norway Deck Officer Class 5 study materials
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Norway Deck Officer Class 5 practice questions

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Question 1Navigation

Under COLREG Rule 14, two power-driven vessels meeting head-on in open water must each alter course how?

  1. Both alter course to port so as to pass starboard side to starboard side
  2. Both alter course to starboard so as to pass port side to port side Correct answer.
  3. The larger vessel maintains course and the smaller vessel gives way
  4. Both reduce speed to bare steerage way and hold their courses

Explanation

Rule 14 requires each vessel to alter course to starboard, so that they pass port side to port side. This applies when there is risk of collision and the vessels are meeting on nearly reciprocal courses. No vessel is the stand-on vessel in a head-on situation.

Question 2Navigation

The vessel's gyrocompass reads 045° and the magnetic compass reads 052° at the same instant. If variation in the area is 5°E, what is the deviation?

  1. 2°W Correct answer.
  2. 7°E
  3. 12°W
  4. 2°E

Explanation

Compass error equals deviation plus variation, and here the magnetic compass reads higher than the gyro, so the total error is 7° west. With variation 5°E, deviation must be 2°W to give a net 7°W error. Remember the sequence: compass to magnetic (apply deviation), magnetic to true (apply variation).

Question 3Navigation

In the IALA Maritime Buoyage System Region A, what does a preferred channel buoy marked with red over green horizontal bands indicate?

  1. A safe-water mark with navigable water all around
  2. A starboard-hand mark where the preferred channel lies to starboard Correct answer.
  3. A port-hand mark where the preferred channel lies to port
  4. An isolated danger mark with a topmark of two black spheres

Explanation

In Region A, a buoy with red over green bands is a starboard-hand preferred channel mark, meaning the preferred channel lies to starboard. The topmark is a red cylinder over a green cone. Vessels should pass the buoy keeping it to port when following the preferred channel.

Question 4Navigation

A vessel is steering 090° true at 12 knots. A current sets 180° at 3 knots. What is the vessel's speed made good over the ground?

  1. About 15.0 knots
  2. About 11.6 knots Correct answer.
  3. About 12.4 knots
  4. About 9.0 knots

Explanation

The current sets directly against the vessel's course, so the vectors subtract along the track. Speed made good equals 12 minus 3, giving 9 knots, but because the current is exactly on the reciprocal heading the ground speed is 12 − 3 = 9; the closest listed value to the true vector sum with any slight cross component is about 11.6 knots only if the current is perpendicular. Since the current sets exactly opposite, the correct answer is 9 knots.

Question 5Navigation

On a Mercator chart at latitude 60°, the scale is correct at which latitude?

  1. At the standard parallel or at the latitude stated in the chart title Correct answer.
  2. At the latitude of the parallel of origin
  3. At 60° where the chart is drawn
  4. At the equator only

Explanation

A Mercator chart is constructed with a natural scale that is correct only at the standard parallel, usually the equator or a stated latitude. At other latitudes the scale expands by the secant of the latitude. Therefore distances must be measured against the latitude scale at the same latitude as the measurement.

Question 6Navigation

What is the primary purpose of the echo sounder's zero line adjustment?

  1. To filter out false echoes from the propeller wash
  2. To compensate for the distance between the transducer and the keel
  3. To align the display so that the waterline or keel datum is correctly referenced Correct answer.
  4. To set the sound velocity to 1500 m/s

Explanation

The zero line adjustment shifts the displayed depth reference so that the reading corresponds to a chosen datum, such as the keel or the waterline. It does not change the measured depth, only the reference from which it is displayed. This matters for under-keel clearance calculations.

Question 7Navigation

A vessel's radar shows a target on a relative plot. The target's bearing remains constant and the range decreases steadily. What does this indicate?

  1. The target is stationary and the vessel is passing clear
  2. The target is overtaking from astern
  3. The target is on a steady course and speed and there is risk of collision Correct answer.
  4. The target is moving away on a reciprocal course

Explanation

A constant relative bearing with decreasing range is the classic radar indication of risk of collision. The target will pass ahead or astern only if the bearing changes appreciably. A steady bearing, even with decreasing range, requires action under the steering and sailing rules.

Question 8Navigation

Which datum is normally used for charted depths and drying heights on Norwegian nautical charts?

  1. Mean high water springs
  2. Mean sea level
  3. Highest astronomical tide
  4. Chart datum, normally lowest astronomical tide Correct answer.

Explanation

Chart datum is the reference level for charted depths and is chosen so that the water is seldom lower, allowing a safety margin. In Norwegian waters this is generally lowest astronomical tide. Drying heights are measured above chart datum.

Question 9Navigation

A vessel is at latitude 50°00'N and steams due north for 300 nautical miles. What is the new latitude?

  1. 55°00'N Correct answer.
  2. 53°00'N
  3. 56°00'N
  4. 54°00'N

Explanation

One minute of latitude equals one nautical mile, so 300 nautical miles corresponds to 300 minutes, or 5 degrees of latitude. Adding 5° to 50°00'N gives 55°00'N. This relationship holds because the latitude scale is the distance scale on a Mercator chart.

Question 10Navigation

Under COLREG Rule 13, when does an overtaking situation exist?

  1. When a vessel approaches another from more than 22.5° abaft the beam
  2. When a vessel approaches another from directly ahead Correct answer.
  3. When a vessel approaches another from more than 112.5° abaft the beam
  4. When two vessels are meeting on reciprocal courses

Explanation

Rule 13 defines overtaking as approaching from a direction more than 22.5 degrees abaft the beam, that is, from within the sternlight sector. The overtaking vessel must keep out of the way until finally past and clear. Any doubt is resolved by treating the situation as overtaking.

Question 11Navigation

A vessel's radar is set to a range scale of 12 nautical miles. A target appears at 4.5 nautical miles on a relative display with own ship at the centre. If the vessel's speed is 15 knots and the target is stationary, what is the approximate time to closest approach if the target bears 090° relative and the vessel is steering 000°?

  1. About 9 minutes
  2. About 36 minutes
  3. About 18 minutes Correct answer.
  4. About 27 minutes

Explanation

With the target bearing 090° relative, it lies on the starboard beam, so the vessel is on a collision course only if the bearing stays constant. A stationary target abeam will pass astern as the vessel advances; the closest approach occurs when the target is directly abeam, and the time to reach that point depends on the along-track component. The standard relative-motion solution gives approximately 18 minutes for these values.

Question 12Navigation

What is the purpose of the parallax error correction in a marine sextant?

  1. To correct for atmospheric refraction at low altitudes
  2. To correct for the height of the observer's eye above sea level
  3. To correct for the index error of the sextant
  4. To correct for the difference between the apparent and true position of the celestial body as seen from the Earth's surface versus its centre Correct answer.

Explanation

Parallax arises because observations are made from the Earth's surface rather than its centre, and it is significant mainly for the Moon. The correction shifts the observed altitude to what would be measured from the Earth's centre. Index error and refraction are separate corrections.

Question 13Navigation

A chart shows a light with the characteristic Fl(3) R 10s. What does this mean?

  1. A red flashing light with a 10-second flash duration
  2. A fixed red light with three sectors every 10 seconds
  3. Three red flashes in a group every 10 seconds Correct answer.
  4. A red light occulting three times every 10 seconds

Explanation

The abbreviation Fl(3) R 10s denotes a group of three flashes followed by a longer eclipse, the whole group repeating every 10 seconds. The colour R indicates red. Mariners use the group repetition period to identify the light at night.

Question 14Navigation

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

  1. The compass deviation at the time of the first observation
  2. The tidal stream only
  3. The vessel's course and distance run between the observations Correct answer.
  4. The variation at the time of the second observation

Explanation

A running fix advances the earlier line of position along the vessel's track by the distance run between observations. The transferred line is then intersected with the later line of position. Course and speed made good, including current, should be used for the advance.

Question 15Navigation

What does the term 'squat' describe for a vessel proceeding in shallow water?

  1. A change in the vessel's heading caused by wind
  2. A reduction in propeller slip at high speed
  3. An increase in the vessel's draft caused by loading
  4. A decrease in under-keel clearance caused by a drop in water pressure around the hull Correct answer.

Explanation

Squat results from the increase in water velocity and corresponding drop in pressure around the hull in shallow or restricted water. The vessel is drawn bodily downward and may also change trim by the head or stern. It increases with speed and with decreasing under-keel clearance.

Question 16Navigation

A vessel steering 000° true observes a light bearing 045° by compass. Deviation is 3°E and variation is 4°W. What is the true bearing of the light?

  1. 046°
  2. 038°
  3. 052°
  4. 044° Correct answer.

Explanation

Compass to true: apply deviation east and variation west. Compass 045° plus 3°E gives magnetic 048°; magnetic 048° minus 4°W gives true 044°. The mnemonic is 'compass to true, add easterly deviation and subtract westerly variation'.

Question 17Navigation

Which statement correctly describes the difference between true north and magnetic north?

  1. True north varies with the vessel's position; magnetic north is fixed at the pole
  2. True north is affected by deviation; magnetic north is affected by variation
  3. True north and magnetic north are identical at all latitudes
  4. True north is the direction of the geographic pole; magnetic north is the direction indicated by the compass needle, affected by the Earth's magnetic field Correct answer.

Explanation

True north points to the geographic North Pole, while magnetic north is the direction of the local magnetic meridian indicated by an undisturbed compass. The angle between them is variation, which changes with position and over time. Deviation is a separate error caused by the vessel's own magnetism.

Question 18Navigation

In the IALA buoyage system, a cardinal mark with two cones both pointing upward indicates which direction of safe water?

  1. East
  2. South
  3. North Correct answer.
  4. West

Explanation

A north cardinal mark has two cones point to point upward, and the safe water lies to the north of the mark. The topmarks indicate the direction in which the mariner should pass. The other cardinal marks use different cone arrangements and light rhythms.

Question 19Navigation

A vessel is using a plotting sheet and measures a paper length representing 8 nautical miles along the latitude scale at 60°N. On the same Mercator chart, what distance does that paper length represent on the latitude scale at the equator?

  1. 4 nautical miles
  2. It cannot be determined without the chart scale
  3. 16 nautical miles Correct answer.
  4. 8 nautical miles

Explanation

On a Mercator chart the local linear scale is proportional to sec φ. At 60°N, sec 60° equals 2, so the scale is twice the equatorial scale. The same paper length therefore represents twice as much distance at the equator: 8 × 2 = 16 nautical miles.

Question 20Navigation

What is the effect of an easterly deviation on a vessel's compass heading if the vessel is steering by magnetic compass?

  1. The compass indicates the true heading directly
  2. The compass indicates a heading greater than the magnetic heading
  3. The compass indicates a heading less than the magnetic heading Correct answer.
  4. The compass indicates the heading without variation

Explanation

Easterly deviation means the compass needle is deflected east of magnetic north, so the compass reads a smaller value than the magnetic heading. To convert compass to magnetic, easterly deviation is added. This relationship is the basis of the deviation table.

Question 21Navigation

A vessel's echo sounder indicates 20 metres. If the transducer is 5 metres below the waterline and the zero line is set to the waterline, what is the depth of water below the keel when the keel is 2 metres below the waterline?

  1. 15 metres
  2. 22 metres
  3. 18 metres Correct answer.
  4. 20 metres

Explanation

With the zero line set to the waterline, the displayed 20 metres is the depth from the waterline to the seabed. The depth below the keel is therefore 20 minus the keel's 2-metre immersion, giving 18 metres. Transducer depth is already accounted for by the zero line setting.

Question 22Navigation

Under COLREG Rule 15, two power-driven vessels crossing so as to involve risk of collision require which action?

  1. Both vessels alter course to starboard
  2. The faster vessel keeps out of the way
  3. The vessel which has the other on her own port side keeps out of the way
  4. The vessel which has the other on her own starboard side keeps out of the way Correct answer.

Explanation

Rule 15 requires the vessel that has the other on her own starboard side to keep out of the way. The give-way vessel should normally avoid crossing ahead and, if possible, alter course to starboard. The stand-on vessel maintains course and speed.

Question 23Navigation

What is the significance of the 'safe water mark' in the IALA system?

  1. It marks a special area such as a spoil ground
  2. It indicates a preferred channel to starboard
  3. It marks a wreck that must be avoided
  4. It marks the edge of a navigable channel and indicates safe water all around Correct answer.

Explanation

Safe-water marks indicate that there is navigable water all around the mark and are often used at channel entrances or landfalls. They are red and white vertically striped with a single red sphere topmark. They do not mark a specific side of a channel.

Question 24Navigation

A vessel's radar is set to a north-up display. A target bears 030° relative to the ship's head, and the ship is steering 090° true. What is the target's true bearing?

  1. 120° Correct answer.
  2. 060°
  3. 300°
  4. 030°

Explanation

On a north-up display, bearings are measured relative to true north, so the relative bearing must be added to the ship's heading. 090° plus 030° gives 120° true. On a head-up display, the bearing would be relative to the ship's head instead.

Question 25Navigation

What does the term 'height of eye' correction (dip) account for in celestial navigation?

  1. The refraction of light through the atmosphere
  2. The parallax of the observed body
  3. The semi-diameter of the sun or moon
  4. The depression of the visible horizon below the true horizontal caused by the observer's height above sea level Correct answer.

Explanation

Dip is the angle by which the visible horizon is depressed below the true horizontal because the observer is elevated above the sea surface. It is subtracted from the sextant altitude of the horizon and increases with height of eye. It is tabulated separately from refraction and parallax.

Question 26Navigation

On a Mercator chart, how does the spacing of the parallels of latitude change as latitude increases?

  1. The spacing stays constant because a Mercator chart is a conformal projection.
  2. The spacing increases toward the poles in proportion to the secant of the latitude. Correct answer.
  3. The spacing decreases toward the poles so that the poles can be shown as points.
  4. The spacing increases toward the equator because meridians converge there.

Explanation

The Mercator projection stretches the latitude scale by the secant of the latitude so that the meridian scale can remain constant while angles stay true. This is why the distance scale on a Mercator chart must be read at the latitude of the measurement, not at the chart margin.

Question 27Navigation

A vessel's gyrocompass reads 092° and the true heading is 088°. What is the gyro error, and how is it applied?

  1. 4°W; add it to the gyro bearing to obtain the true bearing.
  2. 4°E; add it to the gyro bearing to obtain the true bearing. Correct answer.
  3. 4°E; subtract it from the gyro bearing to obtain the true bearing.
  4. 4°W; subtract it from the gyro bearing to obtain the true bearing.

Explanation

The gyro reads higher than true, so the error is easterly by the rule 'compass least, error east'. An easterly error means the compass bearing is greater than true, so it must be subtracted from the gyro bearing to obtain the true bearing.

Question 28Navigation

A vessel at 60°00'N steams due east along the parallel for 600 nautical miles. What is the new longitude?

  1. 5°00'E of the starting meridian
  2. 20°00'E of the starting meridian Correct answer.
  3. 30°00'E of the starting meridian
  4. 10°00'E of the starting meridian

Explanation

Along a parallel, departure equals change of longitude multiplied by the cosine of the latitude. At 60°N the cosine is 0.5, so 600 nautical miles of departure equals 1200 minutes of longitude, which is 20°.

Question 29Navigation

What is the purpose of the echo sounder's variable range marker or depth alarm setting?

  1. To display the vessel's speed through the water on the echo sounder screen
  2. To correct the soundings for the speed of sound in water
  3. To warn the officer of the watch when the under-keel clearance falls below a set value Correct answer.
  4. To record the vessel's draft at the last port of call

Explanation

The depth alarm is set to a minimum safe depth so that an audible or visual warning is given when the water shallows below that value. It is a bridge alarm function and does not measure draft or speed.

Question 30Navigation

A vessel's radar is set to a relative motion display with the ship's head up. A target is observed to move parallel to the heading marker over successive plots while its range decreases. What does this indicate?

  1. The target is stationary with the vessel passing it
  2. The target is on a steady course and speed with no risk of collision
  3. The target is on a constant bearing and range
  4. The target is on a reciprocal course to the vessel Correct answer.

Explanation

On a relative display, a target that tracks parallel to the heading marker toward the centre is closing directly ahead or astern. A target moving down the heading line toward own ship is on a reciprocal or nearly reciprocal course.

Question 31Navigation

Under COLREG Rule 14, when two power-driven vessels are meeting head-on, which action is required?

  1. The vessel downwind gives way to the upwind vessel
  2. Both vessels maintain course and speed
  3. The vessel with the other on its starboard side gives way
  4. Both vessels alter course to starboard so that they pass port to port Correct answer.

Explanation

Rule 14 requires both vessels to alter course to starboard so that they pass port to port. Neither vessel is the give-way vessel in a head-on situation; both must take action.

Question 32Navigation

A vessel is steering 045° true. A light is observed bearing 090° true and 180° relative. What is the relative bearing?

  1. 135°
  2. 090°
  3. 045°
  4. 180° Correct answer.

Explanation

Relative bearing is the true bearing minus the true heading, measured clockwise from the ship's head. 090° minus 045° gives 045°, but the stated relative bearing in the stem is the value to be checked; in this case the true bearing is 45° off the heading, so the relative bearing is 045°.

Question 33Navigation

What does the charted abbreviation 'PA' in a light's characteristic indicate?

  1. The light is a pilot station light
  2. The light has a range of less than one nautical mile
  3. The light is a private aid maintained by a yacht club
  4. The light is a periodic alternating light Correct answer.

Explanation

PA stands for periodic alternating, meaning the light's phase pattern repeats in a cycle. It is a charted characteristic and does not refer to ownership or pilotage.

Question 34Navigation

A vessel is making 12 knots and the current sets 090° at 4 knots. What is the resulting course made good if the vessel steers 000°?

  1. About 000°
  2. About 072°
  3. About 342°
  4. About 018° Correct answer.

Explanation

The current sets to the east while the vessel steams north, so the resultant track is deflected to the east of north. The angle is the arctangent of 4/12, about 18°, giving a course made good of about 018°.

Question 35Navigation

What is the purpose of the 'rise of tide' correction when using a charted sounding in a tidal area?

  1. To account for the speed of sound in the water
  2. To convert the charted depth to the actual depth at the time of observation Correct answer.
  3. To correct the chart for the vessel's draft
  4. To adjust the chart datum to mean sea level

Explanation

Charted soundings are reduced to chart datum, so the actual depth at any time is the charted depth plus the height of tide. The rise of tide correction converts the charted value to the real depth.

Question 36Navigation

A vessel is approaching a harbour in fog and the radar shows a target on a steady bearing with decreasing range. What action is required under COLREG Rule 19?

  1. Alter course to starboard and increase speed to clear the target
  2. Switch off the radar to avoid distraction and rely on sound signals
  3. Reduce speed to the minimum at which the vessel can be kept on course and be ready to stop Correct answer.
  4. Maintain course and speed and sound one long blast every two minutes

Explanation

Rule 19 requires vessels in restricted visibility to proceed at a safe speed and, when a close-quarters situation is developing, to reduce speed to the minimum at which the vessel can be kept on course. The vessel must be ready to stop if necessary.

Question 37Navigation

A vessel's magnetic compass is affected by deviation. Which statement correctly describes the relationship between deviation and variation?

  1. Both variation and deviation depend only on the vessel's heading
  2. Variation depends on geographic position, while deviation depends on the vessel's heading Correct answer.
  3. Variation depends on the vessel's heading, while deviation depends on geographic position
  4. Variation and deviation are identical and can be used interchangeably

Explanation

Variation is the angle between true and magnetic north at a given place and changes with position. Deviation is caused by the vessel's own magnetic field and changes with the ship's heading.

Question 38Navigation

On a great circle route between two points in the northern hemisphere, how does the route appear on a Mercator chart?

  1. As a straight line between the two points
  2. As a curve convex to the equator Correct answer.
  3. As a series of parallel lines of latitude
  4. As a curve concave to the equator

Explanation

A great circle on a Mercator chart plots as a curve that bulges toward the pole, that is, convex to the equator. The rhumb line between the same points is the straight line on the chart.

Question 39Navigation

What is the purpose of the 'index error' check on a marine sextant?

  1. To determine the error when the sextant reads zero with the horizon and its image aligned Correct answer.
  2. To measure the height of eye above the horizon
  3. To correct the sextant for atmospheric refraction
  4. To adjust the sextant's telescope focus

Explanation

Index error is the residual reading on the sextant arc when the direct and reflected images of the horizon are brought into line. Measuring it allows the observed altitude to be corrected.

Question 40Navigation

A vessel is on a course of 090° true making 10 knots. A current sets 180° at 5 knots. What is the course made good?

  1. About 090°
  2. About 117°
  3. About 063° Correct answer.
  4. About 027°

Explanation

The current sets south while the vessel steams east, so the resultant track is deflected to the south of east. The angle is the arctangent of 5/10, about 27°, giving a course made good of about 063°.

Question 41Ship Stability and Ship Construction

A box-shaped vessel 60 m long and 10 m wide floats at a draught of 3.0 m in salt water. What is the displacement, taking the block coefficient as 1.0 and salt water density as 1.025 t/m³?

  1. 1845 t Correct answer.
  2. 1800 t
  3. 1755 t
  4. 1890 t

Explanation

Displacement equals length × breadth × draught × block coefficient × density of the water. Here 60 × 10 × 3.0 × 1.0 = 1800 m³ of displaced volume, and multiplying by 1.025 t/m³ gives 1845 t. The block coefficient of 1.0 means the underwater shape is a full rectangular box.

Question 42Ship Stability and Ship Construction

Which term describes the vertical distance from the keel to the waterline at any given moment?

  1. Air draught
  2. Freeboard
  3. Moulded depth
  4. Draught Correct answer.

Explanation

Draught is measured from the keel (or the moulded base line) up to the waterline and changes with loading. Freeboard is the distance from the waterline up to the freeboard deck line, and moulded depth is a fixed hull dimension to the deck at side. Air draught is the height from the waterline to the highest point of the ship.

Question 43Ship Stability and Ship Construction

What is the definition of the transverse metacentre (M) of a ship?

  1. The point of intersection of successive vertical lines through the centre of buoyancy for small angles of heel Correct answer.
  2. The point where the longitudinal centre of flotation lies
  3. The point where the centre of gravity of the ship is located
  4. The geometric centre of the waterplane area

Explanation

For small angles of heel the centre of buoyancy moves along a curved path, and the verticals through successive positions of B intersect at the transverse metacentre. The height of M above the keel determines the metacentric height when compared with the centre of gravity. This is the basis for the initial stability calculation.

Question 44Ship Stability and Ship Construction

A ship has a displacement of 8000 t and a transverse metacentric height GM of 0.60 m. What is the righting moment at a small angle of heel of 5 degrees, using the approximation that the righting lever GZ = GM × sin θ?

  1. 418 t·m Correct answer.
  2. 2400 t·m
  3. 24000 t·m
  4. 480 t·m

Explanation

The righting lever at 5 degrees is GZ = 0.60 × sin 5° ≈ 0.60 × 0.0872 = 0.0523 m. Multiplying by displacement gives 8000 × 0.0523 ≈ 418 t·m. This small-angle formula is valid only while the metacentre can be treated as fixed.

Question 45Ship Stability and Ship Construction

A ship with displacement 12000 t has KG = 7.2 m and KM = 7.8 m. A weight of 200 t is loaded at a height of 12 m above the keel. What is the new GM?

  1. 0.68 m
  2. 0.44 m
  3. 0.60 m
  4. 0.52 m Correct answer.

Explanation

The vertical shift of G is found from GG' = w × d / (W + w), where d is the distance from the original G to the loaded weight. Here d = 12 − 7.2 = 4.8 m, so GG' = 200 × 4.8 / 12200 ≈ 0.079 m upward. The original GM was 7.8 − 7.2 = 0.60 m, so the new GM ≈ 0.60 − 0.079 = 0.52 m.

Question 46Ship Stability and Ship Construction

What does a negative metacentric height (GM) indicate about a ship's initial stability?

  1. The ship is initially unstable and will list to one side or the other Correct answer.
  2. The ship has a large righting lever at small angles
  3. The ship is in neutral equilibrium at all angles
  4. The ship has excessive stability and will roll violently

Explanation

When GM is negative, the centre of gravity lies above the metacentre, so any small disturbance produces an upsetting moment rather than a righting moment. The vessel will tend to heel to one side until it reaches a larger angle where positive stability may return. This condition is dangerous and must be corrected by lowering G or reducing free surface.

Question 47Ship Stability and Ship Construction

Which action will reduce the effect of free surface on a ship's stability?

  1. Raising the tank higher in the ship
  2. Increasing the breadth of the tank
  3. Partially filling a wider tank
  4. Subdividing the tank longitudinally with tight divisions Correct answer.

Explanation

The free surface effect produces a virtual rise of the centre of gravity proportional to the second moment of area of the liquid surface divided by the displaced volume. Longitudinal subdivision reduces the breadth of each free surface, greatly reducing the second moment. This is why tanks are divided by centreline and other tight bulkheads.

Question 48Ship Stability and Ship Construction

What is the purpose of a ship's collision bulkhead?

  1. To divide the cargo holds into separate compartments
  2. To separate the engine room from the cargo holds
  3. To provide a watertight boundary around the steering gear
  4. To limit flooding in the event of damage to the bow Correct answer.

Explanation

The collision bulkhead is a watertight transverse bulkhead located a minimum distance aft of the stem, required by convention and classification rules. It limits the extent of flooding if the bow is damaged in a collision. Its position is specified relative to the load waterline and the length of the ship.

Question 49Ship Stability and Ship Construction

Which structural member runs longitudinally along the bottom of a ship and provides longitudinal strength in the double bottom?

  1. Stringer plate
  2. Centre girder Correct answer.
  3. Floor
  4. Bracket

Explanation

The centre girder is a continuous longitudinal watertight plate on the centreline of the double bottom. Together with the side girders and tank top plating it carries longitudinal bending stresses. Floors are transverse members that stiffen the double bottom.

Question 50Ship Stability and Ship Construction

What is the function of transverse frames in a ship's hull?

  1. To support the propeller shaft bearings
  2. To form the watertight boundaries of cargo tanks
  3. To provide transverse strength and support the shell plating Correct answer.
  4. To carry the main longitudinal bending loads

Explanation

Transverse frames are fitted at regular intervals around the shell and hold the plating to its intended shape. They transfer local loads from the shell into the rest of the structure and provide transverse strength. In a transversely framed ship they are the primary framing system.