Question 1

Coastal currents and sediment transport: which option describes littoral drift (often associated with the longshore current) most appropriately?

Accepted Answer

Introduction / Context: Littoral drift refers to alongshore sediment transport driven primarily by waves approaching the shoreline at an angle, which set up a nearshore current running parallel to the coast. Recognizing its driver and direction is fundamental for siting harbours, groynes, and nourishment projects. Given Data / Assumptions: Oblique wave approach induces a longshore current in the surf zone. Wind indirectly contributes by generating waves and setup. Transport is predominantly parallel to shore (not perpendicular), moving sand along the coastline. Concept / Approach: The longshore (littoral) current arises from the component of wave momentum flux parallel to the shoreline. While wind is the ultimate energy source for most waves, it is the waves’ tangential component at breaking that directly drives sediment motion alongshore. Step-by-Step Solution: Eliminate perpendicular-current option: that corresponds to rip currents or cross-shore processes, not littoral drift.Eliminate the “raised line of sand” option: that describes a berm or beach ridge, not a process.Select the parallel-to-shore current option, acknowledging wind's role via wave generation. Verification / Alternative check: Shoreline change patterns (updrift accretion/downdrift erosion) confirm the presence of littoral drift aligned with the prevailing wave approach. Why Other Options Are Wrong: Raised line of sand: a morphological feature, not the transport process. Slow wind-driven surface drift offshore: describes general ocean surface drift, not the surf-zone longshore current. Common Pitfalls: Attributing littoral drift directly to wind direction without considering wave approach angle. Final Answer: is a current parallel to the shore, caused due to tangential component of the wind

Question 2

Define a harbour: which combination best captures the functions and facilities typically associated with a harbour in port engineering?

Accepted Answer

Introduction / Context: A harbour is more than a calm patch of water; it is an integrated system that offers protection, berthing, and shore-based infrastructure to support maritime operations. Understanding this holistic definition helps distinguish a simple roadstead from a developed port. Given Data / Assumptions: Shelter from waves and weather for safe mooring and manoeuvring. Facilities for passengers and cargo (quays, terminals, handling equipment). Ancillary commercial buildings (administration, customs, warehouses, support services). Concept / Approach: A basic harbour provides protection; a commercial harbour adds berthing, handling facilities, and landside support, enabling efficient exchange between sea and land transport networks. Step-by-Step Solution: Identify key elements: shelter, operations, and infrastructure.Confirm that each listed item corresponds to a standard harbour function.Select the comprehensive option capturing all three. Verification / Alternative check: Port design manuals describe harbours as protected basins with terminals and support buildings. Why Other Options Are Wrong: Choosing a single function omits critical aspects of a working harbour. Common Pitfalls: Confusing a refuge harbour (shelter only) with a fully developed commercial harbour. Final Answer: all the above.

Question 3

Wave approach and shoreline response: identify the incorrect statement about nearshore hydrodynamics and sediment movement as waves reach the coast.

Accepted Answer

Introduction / Context: As waves shoal and break near the coast, they generate setup (a rise in mean water level toward the shore), longshore currents, and cross-shore transport. Distinguishing correct from incorrect statements about these processes is fundamental in coastal morphology and engineering. Given Data / Assumptions: Oblique waves can create a net drift (longshore current) in the direction of wave advance near breaking. Onshore winds enhance wave growth and can increase coastal water levels via wind setup. Backwash tends to remove finer particles seaward under certain conditions. Concept / Approach: Wave setup produces rising mean water level toward the shoreline, implying a hydraulic gradient that increases landward, not “falling” in the direction of the incoming wave. Therefore, the statement claiming a falling gradient in the direction of the wave is incorrect. Step-by-Step Solution: Check (A): Consistent with Stokes drift and longshore current—acceptable.Check (B): Onshore winds add energy and can raise local mean sea level—acceptable.Check (C): Incorrect—setup means the gradient increases toward shore, not falls.Check (D): Backwash carrying fines seaward is commonly observed—acceptable. Verification / Alternative check: Field measurements of surf-zone setup show higher mean levels near the shoreline compared to offshore during energetic wave conditions. Why Other Options Are Wrong: They align with standard coastal process descriptions; only (C) contradicts observed gradients. Common Pitfalls: Confusing instantaneous wave slopes with mean water level gradients (setup). Final Answer: A falling hydraulic gradient occurs in the direction of the wave

Question 4

Marine geotechnical investigation: borings for soil exploration around waterfront structures are generally extended to what depth below the low-water level to capture foundation-critical strata?

Accepted Answer

Introduction / Context: Reliable foundation design for quay walls, dolphins, and breakwaters requires adequate subsurface data. Marine borings must extend sufficiently below low-water level (L.W.L.) to characterize bearing layers, potential weak strata, and liquefiable or compressible soils that influence stability and settlement. Given Data / Assumptions: Exploration is for typical harbour or nearshore structures. Goal is to intercept all relevant strata affecting load transfer and stability. Standard practice uses a rule-of-thumb depth where detailed project-specific analyses are unavailable. Concept / Approach: As a practical guideline, borings are often taken to a minimum of about 30 m below L.W.L. unless refusal or engineering judgment dictates otherwise. This depth commonly captures soft marine clays, sand lenses, and denser bearing layers needed for design parameters. Step-by-Step Solution: Establish baseline: ensure borings extend beyond the influence zone of foundation stresses.Apply rule-of-thumb: adopt ≈30 m below L.W.L. in absence of site-specific criteria.Adjust in detailed design as per CPT/SPT results and expected foundation type (piles vs gravity). Verification / Alternative check: Project specifications frequently state minimum depths on the order of tens of metres below L.W.L.; 30 m serves as a common baseline. Why Other Options Are Wrong: 35–45 m may be required at some sites but is not the typical minimum guideline; the question asks the general practice. Common Pitfalls: Stopping borings at refusal without alternative methods, missing weaker deeper strata. Final Answer: 30 m

Question 5

Definition of a roadstead in harbour terminology: which statement best describes a roadstead used by vessels near a coast?

Accepted Answer

Introduction / Context: A roadstead is an anchorage outside or inside a harbour where ships can lie at anchor, often sheltered by natural features or artificial works. It is vital for waiting, lighterage, and weathering before entering a harbour proper. Given Data / Assumptions: Serves as a relatively calm water area for safe anchorage and manoeuvring. Protection may be partial (open roadstead) or enhanced by breakwaters (closed roadstead). Used operationally as a holding area for vessels. Concept / Approach: The essential definition focuses on protected navigable water suitable for anchorage and movement, not a terrestrial “road ending.” While some roadsteads are improved by breakwaters, the defining feature is the protected water area itself. Step-by-Step Solution: Select the statement emphasizing a protected water area for safe vessel movement.Recognize that breakwaters may or may not be present; they are not essential to the definition.Reject the “end of the road” option as irrelevant to maritime terminology. Verification / Alternative check: Nautical glossaries define “roadstead” as a sheltered offshore anchorage area. Why Other Options Are Wrong: “End of the road” misinterprets the maritime term. “May be protected by breakwater walls” is true for some cases, but it does not fully define a roadstead; the more general correct definition is option A. Common Pitfalls: Assuming a roadstead must always be breakwater-protected; many are naturally sheltered. Final Answer: is a protected area of water where boats can move safely

Question 6

Atmospheric electricity: The variation of atmospheric potential is caused by which factors?

Accepted Answer

Introduction: Atmospheric potential (the electric potential in the atmosphere) varies due to multiple meteorological and physical factors. Understanding its drivers is part of atmospheric physics and helps explain phenomena like fair-weather electric fields and storm electrification. Given Data / Assumptions: Temperature contrasts exist over Earth's surface. Air density changes with altitude, humidity, and temperature. We consider general, fair-weather contexts absent specific storms. Concept / Approach: Temperature gradients influence convection and charge separation mechanisms, while air density impacts conductivity and ion mobility. Together these alter the vertical potential profile and local electric field intensity observed at the surface and aloft. Step-by-Step Solution: Relate temperature differences to convection cells that transport ions and charge.Link air density changes to electrical conductivity variations that shift potential gradients.Conclude that both factors contribute to atmospheric potential variations. Verification / Alternative check: Balloon and aircraft measurements show diurnal and synoptic-scale variations correlating with temperature structure and density stratification in the troposphere. Why Other Options Are Wrong: a or b alone: Each explains part of the effect but not the full picture.Neither: Contradicts established observations.Ocean waves only: Too narrow; waves can influence local electrification but are not the sole cause. Common Pitfalls: Attributing potential changes to a single factor; the atmosphere is a coupled thermo-electrodynamic system. Final Answer: Both (a) and (b).

Question 7

Wave impact on shore structures: Which actions can be induced on a seawall or pier when a wave strikes and recedes?

Accepted Answer

Introduction: Coastal and harbor structures experience complex dynamic loading from waves. Recognizing the different components of wave-structure interaction is crucial for safe design against sliding, overturning, uplift, and local damage. Given Data / Assumptions: Incident waves with horizontal and vertical momentum components. Structures such as seawalls, quay walls, and pier piles. Breaking/impact, run-up, overtopping, and backwash phases are possible. Concept / Approach: Upon impact, the wave's horizontal momentum generates direct compressive (normal) pressure. Deflection and run-up can impart vertical components, causing shear along surfaces and connections. Breaking waves generate impulsive pressures (slamming). As water recedes, partial vacuum and momentum reversal can induce suction (negative pressure) that tends to pull water away from the structure and uplift elements like slabs or armor units. Step-by-Step Solution: Identify horizontal impact → compressive (normal) force on faces.Recognize vertical deflection → shear components along interfaces.Consider breaking-induced collapse → transient high compressive impulses.During backwash → suction/uplift actions due to pressure drop and returning flow.Therefore, all listed effects can occur; choose the comprehensive option. Verification / Alternative check: Model tests and field observations confirm impulsive slamming pressures and uplift during backwash, which are included in modern design guidelines. Why Other Options Are Wrong: a–d each represents a real effect; none alone is sufficient. The combination reflects real loading envelopes. Common Pitfalls: Designing for mean hydrostatic pressure only; neglecting transient impact and suction can lead to unsafe structures. Final Answer: All of the above.

Question 8

Hydrographic surveying: In locating soundings by the method of two angles from the shore, how many range lines are required to be established?

Accepted Answer

Introduction: Hydrographic surveys position depth soundings using various methods: intersecting ranges, sextant angles, or shore-based theodolite fixes. The method of two angles from the shore fixes the boat's position by observing two angles at known shore stations, avoiding the need for physical range markers. Given Data / Assumptions: Two shore stations are established with known positions. Angles subtended by selected shore marks are measured from these stations to the boat. The objective is to locate the boat (sounding point) by resection/intersection. Concept / Approach: With two observed angles from known points, the boat's position is determined by the intersection of angle loci (arc/line constructs on the chart), not by aligning with pre-set ranges. Range lines are used in the "range method," where the boat keeps alignment with signals; here, angle observations replace them. Step-by-Step Solution: Set up two known shore stations and identify shore marks.Measure two angles to the boat position (or between marks) from these stations.Plot angle loci on the chart; their intersection fixes the boat's coordinates.Since angles suffice, no physical range line is necessary. Verification / Alternative check: Manuals distinguish range (transit) methods from angular fixes. The two-angle method is essentially resection and does not require range beacons. Why Other Options Are Wrong: Single or perpendicular range lines: These are range methods, not angle-based fixes.Three range lines: Overkill and not the described method. Common Pitfalls: Confusing different hydrographic positioning methods; assuming every method needs range beacons. Final Answer: No range line.

Question 9

Tides and lunar effects: Identify the correct combined statement about spring tides, neap tides, and tidal periodicity.

Accepted Answer

Introduction: Tides are driven by the gravitational interaction of the Moon and the Sun with Earth, modulated by Earth's rotation. The question tests basic but essential tidal facts for coastal engineering and navigation. Given Data / Assumptions: Semidiurnal or mixed tidal regimes are considered. New/full moon alignment (syzygy) and first/third quarters (quadrature) are standard lunar phases. Lunar day duration is about 24 hours 50 minutes. Concept / Approach: During syzygy (new/full moon), lunar and solar tidal forces align, producing spring tides (higher highs, lower lows). At quadrature, forces partially cancel, producing neap tides (reduced range). The timing of successive high waters follows the lunar day, hence the ~50-minute daily shift. Step-by-Step Solution: Confirm spring tides at syzygy → statement a true.Confirm neap tides at quadrature → statement b true.Recognize typical ratio of spring to neap ranges ≈ 2:1 (site-dependent) → statement c broadly true.Acknowledge tidal periodicity is tied to the lunar day (~24 h 50 min) → statement d true.Therefore all statements collectively are correct. Verification / Alternative check: Tide tables and harmonic analysis show spring–neap modulation and the 50-minute daily lag consistent with lunar forcing. Why Other Options Are Wrong: Any single statement alone is incomplete; the combined option best represents tidal behavior. Common Pitfalls: Assuming spring tides occur only once a month (they occur near both new and full moon) and ignoring site-specific amplification by resonance and bathymetry. Final Answer: All of the above.

Question 10

Mooring of buoys for large vessels: The buoy is strengthened by connecting to multiple anchors arranged as which type of mooring?

Accepted Answer

Introduction: Buoy moorings must resist environmental forces from waves, wind, and currents transmitted through large vessels. The anchor-leg configuration around a buoy affects holding capacity and positional stability. Given Data / Assumptions: Large vessels impart significant horizontal loads to the buoy. Multiple anchor legs can be distributed around the buoy. We compare 1-, 2-, 3-, and 4-leg systems conceptually. Concept / Approach: A three-legged arrangement (approximately 120° apart) provides near-uniform directional resistance and redundancy, improving station-keeping without excessive complexity. One- or two-leg systems are directionally weak; four-leg systems add complexity and cost, often reserved for very demanding fixed moorings rather than standard mooring buoys. Step-by-Step Solution: Assess directional coverage: 3 legs at ~120° offer balanced restoring force for any approach.Evaluate redundancy: Loss of one leg in a 3-leg system still leaves two legs sharing load with acceptable geometry.Compare with 2-leg or 1-leg: Susceptible to veering loads and yaw; poor omni-directional stability.Four-leg: Effective but more complex and costlier; not the common strengthening choice for buoys serving large vessels. Verification / Alternative check: Harbor practice and design guides frequently show three-point moorings for buoys due to balanced coverage and manageable installation. Why Other Options Are Wrong: One-/Two-legged: Insufficient omni-directional restraint.Four-legged: Possible but not the typical strengthening scheme for standard buoy moorings.All types equally preferred: Not true; three-leg is generally preferred for balance. Common Pitfalls: Assuming more legs always means better; layout symmetry and operational practicality matter as much as count. Final Answer: Three-legged mooring.

Question 11

Tropical circulation basics: Which statements correctly describe heating and large-scale air motion in the tropics?

Accepted Answer

Introduction: Earth’s general circulation is powered by differential heating: strong insolation in the tropics versus weak in the polar regions. This question checks fundamental concepts behind Hadley circulation and meridional heat transport. Given Data / Assumptions: Greater solar input at low latitudes. Air expands and becomes buoyant when heated. Upper-level return flow connects low and high latitudes. Concept / Approach: In the tropics, intense surface heating causes air to warm, expand, and rise near the Intertropical Convergence Zone (ITCZ). Aloft, mass continuity drives outflow poleward; near the surface, relatively cooler, denser air moves equatorward to replace rising air, closing the cell as trade winds after Coriolis deflection. Step-by-Step Solution: Recognize higher net radiation in tropics versus polar regions → stronger surface heating.Warm air becomes less dense and rises; surface pressure falls, drawing in cooler air from higher latitudes.Upper tropospheric outflow carries momentum and heat poleward as part of the Hadley cell.All statements are consistent with the Hadley circulation framework → choose combined option. Verification / Alternative check: Reanalysis datasets show rising motion in the deep tropics, poleward outflow near 200–300 hPa, and surface return trades—consistent with textbook circulation models. Why Other Options Are Wrong: Any single statement alone is incomplete; the general circulation requires all three components.None of the above is contradicted by basic climatology. Common Pitfalls: Ignoring Coriolis deflection (which shapes trades) or confusing seasonal monsoon variability with the mean annual circulation. Final Answer: All of the above.

Question 12

Harbour engineering — floating mooring components (concept check) In a typical floating mooring arrangement used offshore or away from a quay, which of the following shore-side or sea-side elements is NOT required as an essential part of the system?

Accepted Answer

Introduction / Context: Floating moorings are used where ships or small craft cannot come alongside a quay. Vessels pick up a buoy that is held in position by seabed anchors and connected by chains or wire ropes. Understanding which components are essential helps avoid design and operational errors. Given Data / Assumptions: Floating (offshore) mooring point away from the shore. Standard practice uses a buoy connected to anchors via chains/cables. No quay wall or jetty is involved. Concept / Approach: A shore-side bollard is only needed when berthing at a quay. A floating mooring provides the holding point at sea via the buoy; the restraint is supplied by anchors and connecting catenary chains/cables. Hence the shore bollard is not required. Step-by-Step Solution: 1) Identify essential sea-side elements: buoy + anchors + connecting chains.2) Check if the system relies on a shore structure: it does not.3) Conclude that a bollard is not part of a floating mooring. Verification / Alternative check: Typical single-point moorings, fore-and-aft buoys, and trot moorings all exclude shore bollards unless used near a quay, confirming the reasoning. Why Other Options Are Wrong: Cables/chains are mandatory to transmit load to anchors. Anchors provide positional holding against wind/wave/current. The buoy is the floating connection point for the vessel. Common Pitfalls: Confusing floating moorings with quay berthing arrangements. Under-sizing anchor scope/chain length, leading to excessive loads. Final Answer: Bollard (shore-side mooring post).

Question 13

Coastal & maritime basics — wind and extreme air motion phenomena Choose the most accurate comprehensive statement about wind-driven effects and extreme rotating air columns in the marine environment.

Accepted Answer

Introduction / Context: Marine and coastal structures experience environmental loads from wind, waves, and, in rare cases, severe rotating storms. Basic awareness of how wind interacts with the sea surface and structures is essential for conceptual design and risk assessment. Given Data / Assumptions: Wind can both directly load a structure and indirectly generate waves. Vortex formation over water can create surface depressions. Severe rotating air columns (tornadoes/waterspouts) can occur over or near water. Concept / Approach: Design guidance requires considering wind pressures and the waves they induce. Vortical structures in the atmosphere may couple to the water surface, creating observable conical depressions. Tornadoes (and waterspouts over water) are intense rotating columns with high tangential velocities that pose extreme hazards to navigation and infrastructure. Step-by-Step Solution: 1) Recognize wind as a primary wave-generating mechanism affecting offshore design loads.2) Understand that vortices can form depressions at the air-water interface.3) Identify tornado as an extreme rotating atmospheric phenomenon. Verification / Alternative check: Codes and coastal manuals list wind and waves as governing environmental actions. Observations of waterspouts/tornadoes show conical surface depressions, validating options (a)–(c). Why Other Options Are Wrong: “None of the above” contradicts well-established physical behavior and design practice. Common Pitfalls: Separating design for wind and waves; in reality, they are coupled. Ignoring extreme but low-probability events in risk assessments. Final Answer: All of the above.

Question 14

Hydrographic surveying — fixing soundings by “range and one angle” In the “range and one angle” method of locating a sounding, where does the surveyor take the angle measurement while the range line is maintained by shore marks?

Accepted Answer

Introduction / Context: Hydrographic surveys require accurate horizontal positioning of depth measurements (soundings). One practical method is to keep the boat on a pre-set range (transit) defined by two shore marks and take a single angular observation to fix the position along that line. Given Data / Assumptions: A shore transit (range) is visible to the boat crew. One additional observation (an angle) is made to a third conspicuous point. No electronic positioning is assumed. Concept / Approach: The “range” ensures the boat lies on a known straight line. Taking one angle at the boat to a third shore mark provides a second locus that intersects the range at the boat’s instantaneous position, fixing the sounding efficiently without two-shore observer teams. Step-by-Step Solution: 1) Steer the boat to keep the transit marks aligned (on range).2) Measure the angle at the boat between the range line and a selected shore mark (or between two marks).3) Plot the angle from the known range line to intersect at the boat’s location. Verification / Alternative check: Alternative classical methods are “two angles from the shore” and “two angles from the boat.” “Range and one angle” specifically implies the angle instrument is on the boat while the range is provided from shore alignment. Why Other Options Are Wrong: Shore-only angles require a different method (“two angles from shore”). “Either place” is imprecise and defeats the named method’s economy. Angles are essential; otherwise a single range cannot give longitudinal position. Common Pitfalls: Letting the boat drift off the range while taking the angle. Poor selection of the third point leading to bad intersection geometry. Final Answer: On the boat.

Question 15

Definition and features of a dock (harbour works) Which comprehensive statement correctly describes a dock and its essential features and functions?

Accepted Answer

Introduction / Context: Docks are core harbour installations enabling safe, controlled berthing and cargo/passenger operations independent of external water-level fluctuations. Understanding their components is fundamental to port planning and coastal engineering exams. Given Data / Assumptions: “Dock” refers to a closed basin (wet dock/dry dock context) within a harbour system. Objective is to provide controlled water level and access. Infrastructure includes gates and pumping systems as required. Concept / Approach: A dock is an enclosed or partially enclosed basin connected to navigable water. Gates isolate the basin; in dry docks, pumps evacuate water for hull inspection/repairs. In wet docks, level is maintained almost constant to simplify cargo handling and scheduling. Step-by-Step Solution: 1) Identify general function: safe berthing and handling.2) Recognize need for water-level control independent of tide/surge.3) Note structural features: dock gates and pumping equipment. Verification / Alternative check: Harbour manuals distinguish docks from open berths/wharves by the presence of gates and level control; dry docks necessarily use pumps to create a dry working chamber. Why Other Options Are Wrong: Options (a)–(d) each describe true aspects; the inclusive answer is therefore “All the above”. Common Pitfalls: Confusing wet docks (level control) with marinas or open quays (no gates). Assuming all docks are dry docks; many are wet docks used for cargo operations. Final Answer: All the above.

Docks and Harbours Questions