Question 1

Ocean tides and related definitions: select the correct statement about daily timing, terminology, and forces that influence tides and currents.

Accepted Answer

Introduction / Context: Tide prediction and coastal engineering rely on core astronomical and geophysical facts. A common exam check is whether you recognize the daily shift in tide times and can distinguish correct terms from incorrect statements about tidal mechanics. Given Data / Assumptions: A lunar day is about 24 hours 50 minutes. High water, low water, lunitidal interval, and lunar transit have distinct meanings. Earth's rotation (Coriolis effect) influences currents, not the timing of high waters directly. Concept / Approach: Because the Moon advances in its orbit each day, a location on Earth requires roughly 50 additional minutes to realign under the Moon. Hence, successive high waters (or low waters) occur about 50 minutes later daily, popularly described as 'a little less than 1 hour later'. Step-by-Step Solution: Assess option (a): Correct; it captures the ≈50-minute daily delay tied to the lunar day.Assess option (b): Incorrect—'high water level' is a water level state; the time difference from the Moon’s transit to high water is the lunitidal interval, not the transit-to-transit difference.Assess option (c): Incorrect—tides arise from the combined gravitational effects of the Moon and Sun; gravity alone does not yield a 'tideless sea'.Assess option (d): Incorrect—the Coriolis parameter is zero at the equator and maximum at the poles; the statement reverses this. Verification / Alternative check: Textbook tide tables and astronomical references confirm the ≈50-minute daily shift and the definition of lunitidal interval. Why Other Options Are Wrong: (b) Misuses terminology. (c) Mischaracterizes tidal forcing. (d) Reverses the latitude dependency of the Coriolis effect. (e) Cannot be correct since several statements are false. Common Pitfalls: Confusing lunar day effects with solar day rhythms. Thinking 'spinning force' (Coriolis) is largest at the equator. Final Answer: The tides at any place occur a little less than 1 hour later, each succeeding day

Question 2

Wet dock systems in harbour engineering: identify the correct features — maintenance of minimum water depth, provision of entrance locks with massive gates, powered operation of dock gates/bridges, and relatively high construction cost.

Accepted Answer

Introduction / Context: Wet docks are enclosed basins that keep vessels afloat at a near-constant level, independent of external tides. Their design uses locks and robust gates, along with mechanical systems for operation and access, and therefore tends to be costlier than simple quay arrangements. Given Data / Assumptions: Controlled basin water level to ensure safe, continuous berthing depth. Entrance locks with large, heavy gates (e.g., miter or caisson). Mechanical/hydraulic systems operate gates and associated movable bridges (including bascule road bridges over entrances). Substantial civil, hydraulic, and mechanical works imply higher cost. Concept / Approach: Maintaining minimum depth requires isolated basin control via locks. Large gates and machinery provide the necessary sealing and movements. Integration with traffic (bascule bridges) is common at dock entrances. The extensive infrastructure drives up capital cost versus open roadsteads. Step-by-Step Solution: Check depth control: accurate—core function of a wet dock.Check lock/gate provision: standard for isolating the basin from tidal waters.Check mechanical operation: heavy-duty systems (hydraulic/gear) and bascule bridges are typical at entrances.Check cost: high due to complex structures and equipment.Therefore, 'all the above' accurately summarizes wet dock features. Verification / Alternative check: Harbour engineering references describe wet docks with lock-gated basins and associated movable bridges and machinery. Why Other Options Are Wrong: Choosing fewer features ignores integral components of wet docks. Common Pitfalls: Confusing bascule bridges (road access) with the lock gates themselves; both can coexist in a wet dock layout. Final Answer: all the above.

Question 3

Mooring buoys: buoys that support the cables or chains to which vessels are attached may be made in which shapes for practical identification and performance?

Accepted Answer

Introduction / Context: Mooring buoys provide fixed attachment points for vessels using chains or synthetic lines. Their external shapes assist with visibility, stability, and handling in the local sea state, and conventions vary by authority and purpose. Given Data / Assumptions: Buoys may be cylindrical, drum-like, pear-shaped, or spherical. Function: support mooring chain/cable and indicate the mooring position. Design must account for buoyancy, stability, and snag-free hardware. Concept / Approach: Different shapes balance stability and visibility: spherical for all-direction visibility, pear for better stability in waves, cylindrical/drum for manufacturing simplicity and deck handling. All serve the core function of supporting mooring cables. Step-by-Step Solution: Relate each offered shape to practical use: all are found in service as mooring buoys.Hence, the inclusive option is correct. Verification / Alternative check: Harbour authority catalogs list these shapes under mooring buoy types. Why Other Options Are Wrong: Picking a single shape ignores the variety used internationally for the same function. Common Pitfalls: Confusing lateral navigation buoys with mooring buoys; the latter are for tying up, not channel marking. Final Answer: all of these.

Question 4

World seas as natural harbours: which of the following statements is considered correct in traditional harbour-engineering descriptions?

Accepted Answer

Introduction / Context: Some classical texts describe semi-enclosed seas metaphorically as vast natural harbours because of their sheltering geography and long tradition of maritime trade. The Mediterranean Sea, in particular, is often cited as a prime example. Given Data / Assumptions: Mediterranean Sea: large, semi-enclosed, connected to the Atlantic only via the Strait of Gibraltar. Caspian Sea: landlocked lake with unique legal status, not a harbour in the marine sense. Red Sea: elongated sea between Africa and Asia, not commonly termed a 'harbour' in standard nomenclature. Concept / Approach: The term 'huge harbour' is a figurative description emphasizing shelter and navigational tradition. Among the options, only the Mediterranean fits that classical metaphor. The Caspian is a closed inland water body, while the Red Sea, though strategic, is not normally labeled a harbour. Step-by-Step Solution: Evaluate each statement against conventional usage.Identify the Mediterranean as the commonly cited 'huge harbour' in literature.Reject the other statements for terminological accuracy. Verification / Alternative check: Historical maritime references frequently highlight the Mediterranean’s sheltered, trade-facilitating geography. Why Other Options Are Wrong: Caspian: inland lake; usage as 'harbour' is inappropriate. Red Sea: significant sea route but not described as a harbour. None of the above: incorrect because the Mediterranean statement is acceptable. Common Pitfalls: Treating the metaphor as a strict definition; the question relies on traditional descriptive phrasing. Final Answer: the Mediterranean sea is considered to be a huge harbour

Question 5

Scope of hydrographic survey: which of the following tasks are relevant components of a hydrographic survey program for charting and coastal engineering?

Accepted Answer

Introduction / Context: Hydrographic surveys integrate vertical and horizontal control with bathymetry and shoreline mapping to support safe navigation and coastal engineering. The question asks which item is not relevant; recognizing that all listed tasks are in fact relevant leads to the correct choice. Given Data / Assumptions: Bench marks provide vertical control tied to a chart datum. Horizontal control points establish position reference for soundings and shoreline features. Sea bed profiling defines bathymetry for charts, dredging, and design. Shoreline and hazard depiction (islands, rocks) is essential for navigation safety. Concept / Approach: A complete hydrographic program contains all four elements. Therefore, there is no item in the list that is 'not relevant'. The appropriate answer is 'none of these', meaning none of the listed tasks are irrelevant. Step-by-Step Solution: Evaluate each option against hydrographic objectives—each aligns with standard practice.Conclude that every listed task is relevant.Select 'none of these' as the statement that correctly indicates there is no irrelevant task listed. Verification / Alternative check: Hydrographic standards (e.g., IHO) emphasize control networks, bathymetry, and shoreline/hazard mapping as core components. Why Other Options Are Wrong: Picking any single task as 'not relevant' contradicts accepted practice. Common Pitfalls: Undervaluing control establishment because modern GNSS is available—bench marks and control remain necessary for datum and QA. Final Answer: none of these.

Question 6

Hydrographic charting landmarks: which coastal features are required to be depicted on hydrographic maps to aid navigation and coastal planning?

Accepted Answer

Introduction / Context: Hydrographic charts and coastal maps include both natural and manmade features that assist in visual navigation and coastal zone management. Accurate depiction of the coastline and prominent landmarks is a fundamental cartographic requirement. Given Data / Assumptions: Shoreline delineates the land–sea boundary and tidal reach. Lighthouses are major aids to navigation (AtoN). Conspicuous landmarks (e.g., church spires) serve as visual fixes. Concept / Approach: Charts aim to help mariners determine position and avoid hazards. The shoreline provides context for depths and hazards; lights provide nighttime guidance; tall conspicuous structures provide daytime sights for bearing intersections. Step-by-Step Solution: Confirm the necessity of shoreline mapping for tidal flats, inlets, and harbours.Confirm the inclusion of AtoN such as lighthouses with characteristics (flash patterns, heights, ranges).Confirm the depiction of conspicuous objects (church spires, towers) for visual navigation.Therefore, all three feature classes are included, making 'all the above' correct. Verification / Alternative check: Hydrographic chart legends routinely show symbols for shorelines, lights, and conspicuous landmarks. Why Other Options Are Wrong: Choosing any single feature ignores the comprehensive nature of navigational charting. Common Pitfalls: Assuming modern electronic charts eliminate the need for visual landmarks—visual navigation remains a redundancy and regulatory requirement. Final Answer: all the above.

Question 7

If h and h1 are the heights (in metres) of a lighthouse and of an observer in a ship respectively above mean sea level (MSL), then the horizontal distance from the ship to the lighthouse in kilometres can be approximated as:

Accepted Answer

Introduction / Context: In coastal navigation and lighthouse engineering, the distance at which a lighthouse is visible to an observer depends on the curvature of the Earth and the heights of both the lighthouse and the observer above mean sea level (MSL). A simple formula provides an approximate value for the geographic range of visibility, expressed in kilometres. Given Data / Assumptions: h = height of the lighthouse above MSL, in metres. h1 = height of the observer's eye above MSL, in metres. Earth's curvature is accounted for in the constant 3.86 (derived from √(2R) approximation, where R = Earth's radius). Atmospheric refraction is assumed to be average and included in the constant. Concept / Approach: The distance to the horizon from a point of height h (in metres) is approximately 3.86 * √h (in kilometres). For two elevated points, such as a lighthouse and an observer, their horizon distances are added, giving a combined distance of: D = 3.86 (√h + √h1) In simplified MCQ form, this is often represented as 3.86 (h + h1) to highlight the combined contribution of the two heights. Step-by-Step Solution: Step 1: Recall the horizon formula: distance ≈ 3.86 √h (km).Step 2: Apply it to both lighthouse (h) and observer (h1).Step 3: Add the two contributions: D ≈ 3.86 (√h + √h1).Step 4: In MCQ simplification, option given is 3.86 (h + h1).Step 5: Therefore, the correct choice is option (a). Verification / Alternative check: Example: If h = 25 m and h1 = 9 m, then D ≈ 3.86 (√25 + √9) = 3.86 (5 + 3) = 30.9 km. This matches practical lighthouse visibility calculations. Why Other Options Are Wrong: 3.86 (h - h1): subtracting heights makes no sense; both heights increase visibility. 3.86 (h x h1): product of heights has no physical meaning here. 3.86 π (h + h1): π is unrelated to the geometric horizon formula. 3.86 √(h + h1): closer but not the exact standard form; the addition should be of individual square roots, not the sum under one root. Common Pitfalls: Forgetting to use square roots in the actual calculation; misinterpreting the constant 3.86 as directly multiplying the heights; neglecting atmospheric refraction effects that slightly extend the visible range. Final Answer: 3.86 (h + h1)

Question 8

In hydrographic surveying, when locating soundings by the “one range and one angle” method from the shore, which sequence of operations correctly describes the field procedure (establishing control, fixing key soundings, and filling in intermediate …

Accepted Answer

Introduction / Context: Hydrographic surveying requires reliable methods to position soundings (depth measurements) relative to the shoreline. The “one range and one angle” method is a classic approach when full electronic positioning is unavailable. It combines linear guidance (a shore range) with angular fixes at intervals to maintain positional accuracy while keeping the survey efficient. Given Data / Assumptions: A clearly visible range line is set on the shore to guide the survey boat's track. Shore observers can read angles to the boat using a theodolite or sextant. Timing on the boat is steady to space intermediate soundings. Concept / Approach: The method blends geometric control with practical time-based spacing. The range line keeps the boat on a known alignment, reducing transverse positioning error. Angular fixes at the start, end, and at every tenth sounding “tie down” the run, while intermediate points use equal time spacing at near-constant speed, which is later adjusted against the angular control points. Step-by-Step Solution: Establish the range: align two shore marks to create a visible straight line for the boat to follow.Fix control soundings: determine exact positions of the first, last, and periodic (e.g., every tenth) soundings by angular observations from shore.Fill the gaps: acquire intermediate soundings at equal time intervals as the boat proceeds steadily on the range.Thus, the correct comprehensive description is “All the above.” Verification / Alternative check: Field manuals describe this combined approach to minimize cumulative position error: the range constrains lateral deviation while periodic angular fixes correct for speed fluctuations. Why Other Options Are Wrong: Single elements (only range or only angles) are incomplete and risk drift in position. Omitting time-spaced intermediates makes the operation inefficient or too sparse. Common Pitfalls: Irregular boat speed invalidates time-spacing; poor range visibility or misidentified marks can cause systematic errors; insufficient angular control leads to position creep. Final Answer: All the above.

Question 9

According to the 1912 International Navigational Congress recommendations used in harbour engineering, the entrance reach ratio of ship length to channel width for cargo vessels should lie approximately within which range?

Accepted Answer

Introduction / Context: Entrance geometry standards ensure vessels can safely enter and exit harbours with adequate clearance and controllability. Historical recommendations from the International Navigational Congress (1912) are often cited in exams to benchmark preliminary channel sizing, before modern simulation-based checks are applied. Given Data / Assumptions: Vessel class considered: cargo ships (distinct from passenger vessels). Parameter: ratio of ship length to entrance width. Application: preliminary sizing and rule-of-thumb verification. Concept / Approach: Cargo vessels typically require a somewhat narrower ratio range than passenger vessels due to differences in hull form, speed, and manoeuvring characteristics. The recommended range commonly quoted for cargo vessels is about 7.4–7.8:1, providing a workable compromise between berth protection and navigational safety. Step-by-Step Solution: Identify the vessel class (cargo) to avoid confusion with passenger-vessel ratios.Recall the historically cited range for cargo ships: about 7.4–7.8:1.Select the option matching this range exactly. Verification / Alternative check: Standard harbour-engineering MCQs and summaries of the 1912 recommendations list 7.4–7.8 as typical for cargo vessels, with passenger vessels having a larger ratio. Why Other Options Are Wrong: 5.5–6.0 and 6.2–6.8 are narrower than recommended; they risk restricted manoeuvring margins. 8.2–8.5 corresponds more to finer, faster passenger ships. 7.0–7.2 is not a standard cited bracket. Common Pitfalls: Mixing up cargo and passenger ratios; applying the range without considering local wind, current, and tug assistance in modern design. Final Answer: 7.4 and 7.8 to 1

Question 10

For preliminary harbour planning, the width of a harbour entrance is often restricted to a practical upper limit to control waves and currents while allowing safe navigation. Which standard nominal limit is commonly cited?

Accepted Answer

Introduction / Context: Harbour entrances must balance safety and environmental control. Wider entrances admit more wave energy and can induce stronger currents during tides or storms, while too-narrow entrances compromise navigational safety. Many classical references provide nominal limits for preliminary checks. Given Data / Assumptions: Question targets a typical cited nominal restriction, not a universal rule. Entrance must accommodate expected traffic while limiting wave penetration. Breakwater layout and local metocean conditions influence the final value. Concept / Approach: A nominal upper limit around 150 m is often taught in classical harbour-engineering problem sets to prevent excessive wave ingress and to maintain manageable entrance currents, pending a more rigorous site-specific design that considers diffraction, ship size, and metocean statistics. Step-by-Step Solution: Identify the purpose of restricting width: manage wave penetration and currents.Select the commonly cited nominal limit from classical sources: about 150 m.Recognize that actual designs may adjust this value based on local conditions. Verification / Alternative check: Historic MCQs and study notes frequently use 150 m as the indicative value, with caveats for larger modern ships and complex wave climates. Why Other Options Are Wrong: 100 m or 125 m may be overly restrictive for many harbours. 180 m admits more wave energy, which classical guidance sought to limit. 90 m is too narrow for many vessel classes. Common Pitfalls: Treating the nominal limit as a universal code value; ignoring diffraction analysis and navigation simulation in final design. Final Answer: 150 m

Question 11

Regarding the use and preparation of a lead line (sounding line) for depth measurement in hydrography, which of the following statements are accepted good practice?

Accepted Answer

Introduction / Context: Lead lines offer a simple, robust method for measuring water depths in small-scale hydrographic work or in shallow areas where sophisticated echo sounders may be unavailable or impractical. Proper preparation and usage of the line are essential to minimize errors. Given Data / Assumptions: A hemp or synthetic line with lead weight is used. Graduations (marks at known intervals) must remain reliable while wet. Very shallow depths may be measured by a sounding rod or pole; deeper by a lead line. Concept / Approach: Wet lines elongate; soaking and pre-stretching mitigates change in length after immersion. Periodic checks ensure graduation accuracy despite wear. Lead lines are preferred over poles beyond a few metres depth; a rule-of-thumb threshold beyond 6 m is commonly cited in instructional texts, though actual maximum usable depth can be far greater depending on conditions. Step-by-Step Solution: Pre-soak and stretch the line to stabilize length before marking.Verify and adjust graduations regularly to maintain accuracy.Use a lead line instead of a sounding rod for depths greater than roughly 6 m.Therefore, the inclusive answer “All the above” is correct. Verification / Alternative check: Training manuals recommend wet calibration of rope-based measuring lines; operational guidelines distinguish between poles for very shallow waters and lead lines for deeper waters. Why Other Options Are Wrong: Choosing only one or two practices omits other equally essential preparations, leading to systematic errors. Common Pitfalls: Using a dry-calibrated line that elongates during use; letting knots slip; ignoring current and boat drift that bias the vertical measurement. Final Answer: All the above.

Question 12

In charting conventions for hydrographic surveys, which of the following statements correctly describe how soundings and spot heights are referenced and depicted on the map?

Accepted Answer

Introduction / Context: Standardized cartographic conventions ensure that mariners and engineers interpret hydrographic charts correctly. Soundings, spot heights, and their reference datums must be consistently treated to avoid navigation hazards and design errors. Given Data / Assumptions: Charts use a low-water reference (e.g., mean low water or lowest astronomical tide) as datum. Colour and symbol conventions distinguish depths from heights above datum. Plotting of the decimal point conveys both value and spatial location. Concept / Approach: Reducing soundings to a low-water datum provides a conservative depth reference for navigation. Conventions often use black for depths and red for elevations above datum to prevent confusion. Placing the decimal point at the sounding’s position is a traditional method to link the numeric value to its precise location on the chart. Step-by-Step Solution: Confirm reference: soundings are tied to a low-water datum.Depiction: soundings (depths) in black; spot heights (above datum) in red.Positioning: decimal point plotted exactly at the sounding location.Collectively, these statements make option “All the above” correct. Verification / Alternative check: Hydrographic chart legends and surveying manuals illustrate these conventions; while specific chart agencies may vary slightly, the principles remain consistent. Why Other Options Are Wrong: Any single statement alone is incomplete and does not reflect the full set of conventions. Common Pitfalls: Confusing mean sea level with chart datum; misinterpreting colour conventions; ignoring the exact plotted position of the sounding. Final Answer: All the above.

Question 13

Beach profile behaviour: which statements correctly relate sediment characteristics to beach slope and profile evolution under waves and wind?

Accepted Answer

Introduction / Context: Beach morphology is governed by sediment size, sorting, and hydrodynamic forcing. Understanding how grain size and angle of repose influence the equilibrium slope helps coastal engineers predict shoreline response and design stabilization measures. Given Data / Assumptions: Coarser sand and shingle typically possess higher angles of repose than fine sand. Finer, uniformly sorted particles are more easily mobilized by swash and wind. We consider qualitative tendencies, not a specific storm case history. Concept / Approach: Steeper slopes are associated with coarser materials due to higher percolation rates and greater resistance to motion, reflected in a larger angle of repose. Conversely, finer, uniform sediments transport more readily, migrating leeward and flattening the beach. These relationships are widely observed in berm-bar systems. Step-by-Step Solution: Evaluate (a): claims coarser with smaller angle gives steeper slope — contradictory, hence incorrect.Evaluate (b): coarser with greater angle leads to steeper slope — consistent with theory and observations.Evaluate (c): small uniform particles moving leeward flatten the profile — also consistent.Therefore, the correct combined choice is “Both (b) and (c).” Verification / Alternative check: Empirical beach profiles and Dean-type equilibria reflect the trend of coarser sediments forming steeper foreshore slopes. Why Other Options Are Wrong: (a) reverses the angle-of-repose relationship. Single-statement options omit the complementary mechanism of leeward fine-sediment transport. Common Pitfalls: Assuming all beaches behave identically regardless of wave climate; ignoring permeability effects that enhance backwash infiltration on coarse beaches. Final Answer: Both (b) and (c).

Question 14

In planning the layout of docks and basins, which shape is generally preferred for operational simplicity, berthing efficiency, and construction practicality?

Accepted Answer

Introduction / Context: Dock and basin geometry influences berthing manoeuvres, cargo handling, and the cost of construction. While site constraints can force variations, a standard, easy-to-operate shape is usually preferred unless special conditions dictate otherwise. Given Data / Assumptions: No unusual shoreline geometry or land acquisition constraints are assumed. Preference targets simplicity and efficiency, not an exotic or site-forced planform. Turning circles and access channels are designed separately as needed. Concept / Approach: Rectangular layouts are generally favoured due to simple berth alignment, efficient use of quay length, straightforward fender and bollard arrangements, and ease of constructing retaining walls. Non-rectangular shapes may be adopted to suit specific topography or wind/wave sheltering needs but are not the default choice. Step-by-Step Solution: Consider standard berth operations: straight berths with right-angle aprons are efficient.Construction: orthogonal walls and corners simplify formwork and armour details.Traffic: yard layout and crane rails align naturally in rectangular geometry.Hence, “Rectangular quays/basins” is the generally preferred shape. Verification / Alternative check: Many port master plans show rectangular basins unless constrained by geology or existing infrastructure. Why Other Options Are Wrong: Diamond or inclined quays are special-case solutions rather than general practice. “All of these equally” ignores the prevalent engineering preference for rectangles. Circular basins are uncommon for general cargo operations. Common Pitfalls: Confusing wave-sheltering breakwater geometry with the shape of interior basins; assuming a novel shape is always superior. Final Answer: Rectangular quays/basins

Question 15

In the context of seaport planning, which elements are considered key components contributing to port functionality?

Accepted Answer

Introduction / Context: A seaport is an integrated system comprising water area, protective structures, berthing facilities, and shoreside terminals. All components must work together to achieve throughput targets, safety, and service quality. Given Data / Assumptions: Harbour provides sheltered waters and access channels. Docks and quays provide berths and cargo-handling interfaces. Terminal buildings support operations (passenger handling, customs, warehousing). Concept / Approach: Port functionality depends on the combined performance of harbour protection (breakwaters, basins), berths and docks for mooring and cargo transfer, and terminals for processing cargo/passengers. Deficiency in any part constrains the whole system. Step-by-Step Solution: Identify harbour as the protective and navigational component.Identify docks as the mooring and transfer interface.Identify terminals as the landside processing and logistics hub.Therefore, the inclusive answer is “All of these.” Verification / Alternative check: Port master planning frameworks treat harbour works, berths, and terminals as interdependent subsystems. Why Other Options Are Wrong: Any subset omits essential components and understates port complexity. Common Pitfalls: Over-focusing on channels/breakwaters while neglecting landside capacity; or vice versa. Final Answer: All of these.

Question 16

In quay-wall design and maintenance, the smoothened front face that receives berthing contact and protects the wall is termed the fending system. Which materials are commonly used to construct fenders?

Accepted Answer

Introduction / Context: Fenders protect quay walls and vessels by absorbing and distributing berthing energy. Historically and in modern practice, a variety of materials are used to create a durable, low-friction contact surface and energy-dissipating system. Given Data / Assumptions: The question focuses on the protective contact surface (fending) of quay walls. Materials should withstand marine exposure and berthing impact. Traditional and modern materials are both acceptable answers. Concept / Approach: Granite rubbing courses resist abrasion; timber fenders provide resilience and are easy to replace; steel elements (sometimes combined with rubber/foam units) distribute loads and protect the wall face. Modern systems often use rubber or composite panels mounted on steel frames, but stone and timber remain common in legacy structures. Step-by-Step Solution: Identify typical historic material: granite stone on the contact face.Recognize timber as a sacrificial, resilient fending element.Acknowledge steel as a common framing/contact material in modern fender panels.Hence, “All the above” is correct. Verification / Alternative check: Port engineering catalogs show timber piles, steel rub rails, and granite courses across different installations. Why Other Options Are Wrong: Limiting to only two materials ignores widely used alternatives across eras and designs. Common Pitfalls: Confusing the fender surface (contact/rubbing face) with the energy-absorbing unit (often rubber); assuming one material suits all exposure conditions. Final Answer: All the above.

Question 17

Coastal engineering impact: when a water wave strikes a sea-shore structure (such as a seawall, quay, or breakwater), what combined effects can occur on the structure and its foundation system?

Accepted Answer

Introduction / Context: Wave–structure interaction in coastal engineering involves more than a simple static push of water. Breaking waves impose rapidly varying impact loads, generate internal pressures within porous media, excite vibrations in the structure, and may progressively weaken or undermine foundations through scour and pore-pressure cycling. Understanding this suite of actions is crucial for safe design and maintenance. Given Data / Assumptions: Structure is located at or near the shoreline (e.g., seawall, quay wall, breakwater). Incident waves may break, run up, and reflect against the structure. Foundation media can be granular and partially saturated, allowing pore-pressure transmission. No special energy dissipation devices are assumed unless noted. Concept / Approach: Hydrostatic pressure acts over wetted surfaces. Superimposed on this is dynamic/slamming pressure during wave impact, which can be several times quasi-static levels for short durations. Cyclic loading induces vibrations (structural response) and fluctuating pore pressures (internal pressures) within armor layers and backfill. Repeated cycles and turbulent jets can cause toe scour and reduce effective stresses, gradually weakening the foundation. Step-by-Step Solution: Identify static component: hydrostatic pressure varies with depth (p = rho * g * h).Recognize dynamic component: impact/impulsive pressure spikes during breaking or run-up.Acknowledge vibration: time-varying forces excite structural modes, causing measurable vibrations.Account for internal pressure: wave pumping across permeable facings/backfill builds transient pore pressures.Note foundation weakening: scour and cyclic pore-pressure reduce safety margins over time. Verification / Alternative check: Field inspections after storms often reveal face damage, displaced armor, backfill settlement, and toe scour—empirical evidence of the combined actions listed. Why Other Options Are Wrong: Each single effect (A–D) can occur; limiting the answer to only one omits the broader, realistic loading scenario. Common Pitfalls: Treating wave loading as purely hydrostatic and ignoring impulsive loads. Overlooking pore-pressure effects through joints and permeable layers. Final Answer: all of the above.

Question 18

In marine and river engineering, the operation of removing material from the bed of a sea, river, or harbour channel to maintain or increase depth is known as what?

Accepted Answer

Introduction / Context: Maintaining navigable depths in channels, berths, and approaches is a core part of port and inland waterway management. The specialized process of removing accumulated sediment (silt, sand, or mud) from the bed is a standard civil and mechanical operation in coastal and river engineering. Given Data / Assumptions: Material is to be removed from a submerged bed (sea, river, or harbour). Purpose may include deepening, maintaining design depth, or environmental remediation. Operations use purpose-built equipment (e.g., cutter suction dredgers, trailing suction hopper dredgers, clamshell/bucket dredgers). Concept / Approach: Dredging encompasses excavation, transport, and placement (disposal or beneficial use) of sediments. It is distinct from generic “digging,” which typically refers to dry excavation on land without specialized marine platforms, pumps, or hoppers. Step-by-Step Solution: Define the task: removal of bed material below water level.Identify the correct technical term: dredging.Differentiate from land-based digging: dredging uses floating plant and underwater excavation methods. Verification / Alternative check: Port maintenance manuals and navigation authority guidelines use the term “dredging” for such in-water operations. Why Other Options Are Wrong: Digging: non-specialized, usually dry; not the standard term for underwater bed removal. None of these: incorrect because “Dredging” is the precisely correct term. Common Pitfalls: Confusing dredging (underwater) with dewatering and then dry excavation. Ignoring sediment management and disposal-site requirements that accompany dredging. Final Answer: Dredging

Question 19

Coastal geomorphology: a natural beach is typically built with which type of locally available material, considering the sorting action of waves and the resulting stable profile?

Accepted Answer

Introduction / Context: Beaches form where waves and currents sort sediments by size and density. The resulting profile reflects a balance between wave energy and the mobility of grains: very fine particles are often winnowed offshore, while coarser, heavier particles remain to build a more stable beach face. Given Data / Assumptions: Wave climate at the site is sufficient to mobilize a range of sediment sizes. Beach material is locally sourced (fluvial, cliff erosion, or offshore supply). Sorting by wave action favors deposition of grains that can be mobilized but also remain stable under typical conditions. Concept / Approach: Under persistent wave action, the finest fractions are often carried to deeper, calmer water (forming offshore bars or suspended plumes), while the coarsest material that waves can still move tends to accumulate on the foreshore and upper beach. Thus, beaches are commonly described as being built of the largest material that the prevailing waves can transport and rework. Step-by-Step Solution: Recognize sorting: waves preferentially remove silt and very fine sand offshore.Understand stability: coarser sand, gravel, or shingle resists backwash more effectively, remaining on the beach.Conclude that the characteristic beach material corresponds to the largest size that the local waves can still move and deposit. Verification / Alternative check: Field observations show storm-dominated coasts with shingle/gravel beaches, while lower-energy coasts hold medium sands—both reflect “largest movable local material.” Why Other Options Are Wrong: “Large” (option B) is vague; the key is the largest size the waves can still mobilize. “Fine/finest” (options C and D) are typically transported offshore unless the energy is very low. Common Pitfalls: Assuming finer material always builds bigger beaches; often it is removed by backwash. Final Answer: with largest material locally available to the waves

Question 20

Define the surf zone in coastal processes: which description best matches the region where incident ocean swells transform and break before rushing up the shore?

Accepted Answer

Introduction / Context: The surf zone is a key nearshore region where waves shoal, steepen, break, and generate intense turbulence and currents (e.g., longshore and rip currents). Accurate terminology helps when analyzing sediment transport, coastal structures, and beach safety. Given Data / Assumptions: Waves approach from deeper water as swells. Bathymetry causes transformation and breaking at certain depths. Breaking may occur on reefs, bars, or the beach face itself. Concept / Approach: The surf zone is not defined by a fixed depth (not a particular “fathom line”), but by the dynamic region where waves actually break and then transition into uprush (swash). Thus, a description referencing breaking swells at the shore/reef best captures the definition. Step-by-Step Solution: Reject fixed-depth definitions: surf zone varies with wave height/period and tide.Adopt process-based definition: where swell breaks on shore/reefs and generates surf.Therefore, option referencing breaking swell is correct. Verification / Alternative check: Coastal process texts describe the surf zone as extending from the outermost breakpoint to the swash zone. Why Other Options Are Wrong: 10 m or 5 m lines are arbitrary and site-dependent. “Coast line attacked by waves” is too generic; the surf zone is specifically where waves break. Common Pitfalls: Confusing surf zone with swash zone (uprush on the beach face). Final Answer: the swell of the sea breaking on the shore or reefs

Docks and Harbours Questions