# Docks and Harbor Engineering Questions & Answers

1. Assertion A : Depth and width required at the entrance to a harbour are more than those required in the channel.
Reason R : The entrance to a harbour is usually more exposed to waves as compared to the harbour itself.
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true but R is not the correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.
Ans: a

2. When a ship floats at its designed water line, the vertical distance from water line to the bottom of the ship is known as
a) beam
b) depth
c) freeboard
d) draft
Ans: d

3. The maximum harbour depth below lowest low water is generally equal to
(i) loaded draft + 1.2 m when bottom is rock
(ii) loaded draft + 1.8 m when bottom is soft
(iii) loaded draft + 1.2 m when bottom is soft
(iv) loaded draft + 1.8 m when bottom is rock
Of these statements
a) (i) and (ii) are correct
b) (i) and (iii) are correct
c) (ii) and (iv) are correct
d) (iii) and (iv) are correct
Ans: d

4. The minimum diameter of turning besin, where ships turn by going ahead and without tug assistance should be
a) L
b) 1.5 L
c) 2.0 L
d) 4.0 L
where L is the length of the largest ship to use the port
Ans: d

5. Dead weight tonnage of a ship
i) varies with latitude and season
ii) is more than displacement tonnage
iii) is the difference between displacement load and displacement light Of these statements
a) i) and ii) are correct
b) ii) and iii) are correct
c) i) and iii) are correct
d) Only iii) is correct
Ans: c

6. In basins subjected to strong winds and tide, the length of the berthing area should not be less than
a) the length of design vessel
b) the length of design vessel + 10% clearance between adjacent vessels
c) the length of design vessel + 20% clearance between adjacent vessels
d) twice the length of design vessel
Ans: c

7. As per Stevenson’s empirical formula, the approximate value of the height of the wave in metres is given by
a) 0.34 VF
b) 0.5 VF
c) 1.5 VF
d) 3.4 VF
where F is the fetch in km.
Ans: a

8. As per Berlin’s formula, the length of wave in metres is given by
a) 1.3412
b) 1.5612
c) 1.7412
d) 1.9412
where ‘t’ is the period in seconds for two successive waves to pass the same section.
Ans: b

9. Assertion A : Intervention of undulations in the sea bed reduces the depth of wave at the section.
Reason R : No wave can have a height greater than the depth of water through which it passes.
a) Both A and R are true and R is correct explanation of A.
b) Both A and R are true but R is not the correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.
Ans: a

10. Consider the following statements in regard to Beaufort scale for wind speeds,
(i) The Beaufort number ranges from 1 to 12.
(ii) Higher Beaufort number indicates higher speed of wind,
(iii) Beaufort number for calm is smallest and for hurricane is highest Of these statements
a) (i) and (ii) are correct
b) (ii) and (iii) are correct
c) (i) and (iii) are correct
d) (i), (ii) and (iii) are correct
Ans: b

11. At a given port, the fetch is 400 nautical miles, the maximum height of storm wave will be
a) 2.073 m
b) 8.169 m
c) 9.144 m
d) 6.8 m
Ans: c

12. In a two lane channel, bottom width of channel is given by
a) Manoeuvring lane + 2 x Bank clearance lane
b) 2 x Manoeuvring lane + 2 x Bank clearance lane
c) 2 x Manoeuvring lane + 2 x Bank clearance lane + ship clearance lane
d) Manoeuvring lane + 2 x Bank clearance lane + ship clearance lane
Ans: c

13. Minimum width of ship clearance shall be
a) B or 30 m
b) 1.5 B or 50 m
c) 1.5 B
d) 50 m
where “B” is beam of the design vessel
Ans: a

14. Select the incorrect statement.
a) The progress of work in low level method of mound construction is very slow.
b) Barge method of mound construction is economical.
c) In low level method of mound construction, the area of working is limited.
d) In staging method of mound cons-truction, the work is not interrupted even during stormy weather.
Ans: b

15. Assertion A : Marine structures are made specially bulky and strong.
Reason R : Sea insects result in undermining of the hardest and the soundest building material. Select your answer based on the coding system given below:
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true but R is not the correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.
Ans: a

16. The most popular method of construction of wall breakwaters is
a) Barge method
b) Staging method
c) Low level method
d) none of the above
Ans:

17. As compared to wall type breakwater, mound type breakwater
a) requires skilled labour
b) requires low maintenance cost
c) requires less material
d) results in less damage due to gradual failure
Ans: d

18. The difference in height between highest high water and lowest low water is called
a) mean range
b) maximum range
c) maximum rise
d) mean rise
Ans: b

19. If the maximum spring rise is 2 m and height of the waves expected is 4 m , then the breakwater height above the datum will be
a) 2.5 m
b) 4 m
c) 5 m
d) 7 m
Ans: d

20. If H is the height of the wave expected, then the height of the breakwater is generally taken as
a) 1.2 H to 1.25 H above the datum
b) 1.2 H to 1.25 H above the low water level
c) 1.2 H to 1.25 H above the high water level
d) 1.2 H to 1.25 H above the mean sea level
Ans: c

21. Assertion A : Basin walls have to be of much grater height than dock walls.
Reason R : Tidal basins are subject to fluctuations of levels due to tidal variations.
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true but R is not correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.
Ans: a

22. In multiple point mooring system, vessel is secured to minimum of
a) two points
b) four points
c) six points
d) eight points
Ans: b

23. By increasing the rise of lockgates,
(i) the length of the lock gate will increase
(ii) transverse stress due to water pressure on the gate will increase
(iii) compressive force on the gate will increase Of these statements
a) (i) and (ii) are correct
b) (i) and (iii) are correct
c) Only (ii) is correct
d) Only (iii) is correct
Ans: a

24. Which of the following is a fixed type mooring accessory ?
a) bollard
b) buoys
c) cables
d) anchors
Ans: a

25. The significant wave height is defined is the average height of the
a) one – third highest waves
b) one – fourth highest waves
c) one – fifth highest waves
d) one – tenth highest waves
Ans: a

26. If Hs is the significant wave height, then the average wave height and highest wave height respectively are given by
a) 0.6 Hs and 1.67 Hs
b) 0.6 Hs and 1.87 Hs
c) 1.27 Hs and 1.87 Hs
d) 1.27 Hs and 1.67 Hs
Ans: b

27. When a wave strikes a vertical breakwater in deep water, it is reflected back and on meeting another advancing wave of similar amplitude merges and rises vertically in a wall of water. This phenomenon is called
a) Surf
b) Clapotis
c) Fetch
d) Swell
Ans: b

28. Which of the following structures are constructed parallel to shore line to develop a demarcating line between land area and water area ?
a) sea walls, bulk heads and groynes
b) sea walls, bulk heads and revetments
c) sea walls, revetments and groynes
d) bulk heads, revetments and groynes
Ans: b

29. Which of the following type of sea walls results in greatest protection of shore structures?
a) vertical sea wall
b) sea wall with batter
c) stepped sea wall
d) sea wall with concave face
Ans: d

30. Assertion A : Large size stones are required in stone revetment in shore protection.
Reason R : Resistance of stone to wave force is proportional to its volume and wave force is proportional to the exposed area of the stone.
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true but R is not a correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.
Ans: a

31. Which of the following are repair docks ?
a) marine railways, dry docks, floating docks, wet docks
b) dry docks, wet docks, floating docks, lift docks
c) wet docks, floating docks, lift docks, marine railways
d) wet docks, lift docks, marine railways, dry docks
Ans: c

32. Which of the following structures protects the shore by trapping of littoral drift?
a) groynes
b) sea walls
c) revetments
d) moles
Ans: a

33. Which of the following conditions of loading imposes the greatest load on the foundation in case of dry docks?
a) when the dock is empty
b) when the dock is empty with the ship of maximum tonnage
c) when the dock is full of water
d) when the dock is dry and is under construction
Ans: c

34. For designing the dock, the proportion of ship load assumed to be borne by keel blocks is
a) 5/8
b) 3/8
c) 3/16
d) 5/16
Ans: a

35. A ship strikes the berth generally at an angle
a) 90° with the face of the dock
b) 45° with the face of the dock
c) 30° with the face of the dock
d) 10° with the face of the dock
Ans: d

36. Consider the following statements.
(i) Fender is the cushion provided on the face of the jetty for ships to come in contact,
(ii) Slip is the space of water area between two adjacent piers where ships are berthed,
(iii) Pier head is a structure constructed near the tip of a break water near the harbour entrance. Of the statements
a) (i) and (ii) are correct
b) (ii) and (iii) are correct
c) (i) and (iii) are correct
d) (i), (ii) and (iii) are correct
Ans: d

37. A ship is berthed in a chamber and lifted by principles of buoyancy Such a chamber is called.
a) Dry dock
b) Wet dock
c) Floating dock
d) Refuge dock
Ans: c