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Bollard pull

Bollard pull is a conventional measure of the pulling or towing power of a watercraft, defined as the maximum static thrust generated by its propulsion system at zero forward speed under full power.^[1]^[2] This metric, analogous to horsepower in land vehicles, quantifies a vessel's ability to exert horizontal force against a fixed object, such as a pier bollard, without forward motion.^[1] It is most commonly applied to tugboats and anchor-handling vessels, where it serves as a key indicator of performance in stationary towing scenarios.^[2] The measurement of bollard pull involves a standardized test where the vessel is secured to a fixed bollard via a towline equipped with a load cell to record tension, conducted under controlled conditions like calm water, minimal current, and even draft to ensure accuracy.^[1] Results are expressed in units such as kilonewtons (kN), short tons of force (stf), or tonnes of force (tf), with typical values ranging from 500–600 kN for medium-sized tugs to around 4,700 kN for advanced anchor-handling tug supply (AHTS) vessels like the Island Victory, which holds the record with 477 tonnes-force (approximately 4,680 kN) as of 2025.^[1]^[3] Calculations often incorporate factors such as propeller diameter, delivered power, and efficiency losses, using empirical formulas like bollard pull (in tons) = (thrust in kN × efficiency factors) / 9.81, where thrust is derived from (propeller diameter × power)^{2/3}.^[2] Propeller nozzles can enhance this thrust by 20–40% compared to open propellers, optimizing performance for low-speed operations.^[2] Bollard pull is critical in the maritime industry for assessing a vessel's towing capacity, ensuring safe harbor maneuvers, and supporting operations such as oil rig towing or emergency assistance.^[1] Internationally recognized certification of bollard pull is required for tugs to operate in ports, influencing logistics planning and vessel selection based on environmental factors like wind, waves, and currents that affect total towing force.^[1]^[4] Historically, the concept emerged to evaluate tugs' ability to haul heavy loads in stationary conditions, evolving into a fundamental specification for modern ship-assist vessels with propulsion systems designed for maximum thrust near zero speed.^[1]^[2]

Fundamentals

Definition

Bollard pull is defined as the maximum static thrust or pulling force that a vessel's propulsion system can generate when operating at zero forward speed and full engine power. This metric represents the tractive force exerted by the propeller or thrusters in a stationary condition, typically measured in tonnes or kilonewtons.^[1]^[5]^[6] Unlike horsepower, which measures power output in land vehicles and emphasizes the rate of work involving both force and speed, bollard pull specifically quantifies force alone, independent of motion. This focus makes it a direct indicator of a vessel's raw pulling capacity, akin to torque in automotive contexts but tailored to maritime propulsion.^[1] The concept isolates the propulsion system's performance by eliminating hydrodynamic influences such as forward velocity, wake formation, or water flow over the hull, thereby providing a pure measure of towing potential in static scenarios. In practice, it is essential for assessing a vessel's ability to perform tasks like holding position against external forces or initiating tows without acceleration effects.^[7]^[1] The term "bollard pull" derives from the traditional testing method, where a vessel is secured by a towline to a fixed dockside bollard—a sturdy post used for mooring—and the maximum force it exerts is recorded. This nomenclature emerged in maritime engineering practices, with formalized trials documented as early as the 1960s by organizations like the British Ship Research Association.^[8]^[7]

Units and Standards

Bollard pull is conventionally expressed in metric tonnes-force (tf), a unit representing the force exerted by one metric tonne under standard gravity, where 1 tf ≈ 9.81 kilonewtons (kN).^[9] This unit is preferred in global maritime contexts for its alignment with the International System of Units (SI) and ease of application in engineering calculations. In some United States-based operations, short tons-force (stf) may be used, equivalent to approximately 8.90 kN, though international standards strongly favor the metric tonne to ensure consistency across borders.^[10] International standards for bollard pull reporting and certification are established by bodies such as the International Towing Tank Conference (ITTC), which provides procedures for consistent measurement and documentation in propulsion tests, often referencing SI units like newtons for precision in model-scale validations.^[11] Classification societies, including the American Bureau of Shipping (ABS) and Det Norske Veritas (DNV), mandate certified values in tonnes-force for vessel approval, with ABS specifying metric or long tons-force and requiring trials at maximum continuous RPM for compliance.^[10] DNV similarly certifies continuous static bollard pull in tonnes, integrating it into operational guidelines for specialized vessels.^[12] A key distinction exists between static (peak) bollard pull, which captures the maximum initial force, and continuous bollard pull, defined as the sustained average force over 5-10 minutes without exceeding the peak for more than 30 seconds.^[13] ABS standards emphasize averaging over 3-5 minutes while ignoring transient spikes to determine this continuous value at equilibrium.^[10] These definitions ensure reliable certification for towing capabilities, with continuous pull serving as the primary metric for practical vessel classification.^[12]

Historical Development

Origins in Maritime Engineering

The concept of bollard pull emerged in the early 20th century alongside advancements in tugboat propulsion, building on the foundations laid by 19th-century steam-powered tugs that revolutionized harbor operations by enabling powered assistance for larger sailing vessels. The first practical steam tug, the Charlotte Dundas, was built in 1803 by William Symington in Scotland to tow barges on canals, though it saw limited commercial use due to reliability issues.^[14] Steam tugs appeared in New York Harbor in the 1820s, with the industry taking shape by 1828 using converted paddle-wheelers for towing.^[15] Early evaluations of these vessels focused on practical thrust and horsepower rather than standardized static pull metrics, which developed later. In the early 20th century, shipbuilders conducted comparative trials to evaluate tug efficiency beyond simple horsepower ratings, which often overstated effective pulling power due to variations in transmission and propeller design. This shift was influenced by naval architecture advancements, particularly the 1932 invention of the Kort nozzle by Ludwig Kort, which enclosed the propeller in a duct to boost thrust by 30-40% at low speeds, emphasizing direct measurement of static pull over engine output alone. Introduced during the interwar period (1918-1939), bollard pull gained traction as a standardized way to quantify a tug's stationary pulling force, addressing inconsistencies in power reporting that plagued earlier assessments.^[16]^[8] The metric received its first formal recognition in the mid-20th century, coinciding with the post-World War II expansion of harbor tug operations driven by the rise of supertankers and larger merchant vessels. After the war, tug horsepower escalated from a few thousand to over 10,000, necessitating reliable metrics for safety and efficiency in congested ports, where bollard pull trials became essential for verifying a vessel's ability to handle increased loads. In 1961, the British Ship Research Association developed the first codified bollard pull trial procedures, formalizing tests that measured maximum static thrust in tonnes, typically achieving ratios of 1-1.3 tonnes per 100 horsepower for conventional designs. This standardization supported the rapid growth in global tug fleets, enabling precise comparisons and contractual specifications for harbor services.^[16]^[8]

Evolution of Testing Protocols

The evolution of bollard pull testing protocols marked a transition from informal, manufacturer-conducted assessments to rigorous, independent verifications, driven by the need for reliable performance data in increasingly complex maritime operations. In the late 1970s, the United Kingdom saw the initiation of the first recorded third-party bollard pull trials, conducted under supervised conditions to ensure objectivity and accuracy in measuring tug capabilities.^[8] This approach was soon adopted in Australia in 1981, where similar independent trials established a precedent for external validation, reducing discrepancies arising from self-reported results by shipbuilders.^[8] A pivotal development in the 1980s involved classification societies issuing formal guidelines that mandated bollard pull certification for tugs exceeding specific size thresholds, typically those over 500 gross tons or with propulsion powers above certain limits, to guarantee safe towing operations. Det Norske Veritas pioneered these requirements in the late 1970s, emphasizing standardized environmental conditions and measurement techniques, followed by the American Bureau of Shipping and other societies that aligned their rules to promote consistency across international fleets.^[8] These guidelines specified factors such as towline length, engine loading durations (often 5-30 minutes at maximum power), and minimal current influences, laying the groundwork for broader regulatory harmonization. From the 1990s onward, international bodies like the International Towing Tank Conference (ITTC) integrated bollard pull protocols into their recommended procedures, adopting specifications for trial conditions including minimum water depths (typically over 20 meters) and towline angles (ideally horizontal to simulate real-world towing).^[11] This culminated in the 2017 ITTC guidelines (revision 05), which formalized methodologies for propulsion and bollard pull tests to enhance comparability across vessels.^[11] In parallel, efforts toward a unified international standard accelerated, leading to the 2019 International Standard for Bollard Pull Trials developed through a joint industry project involving multiple classification societies, which further refined conditions like fixed engine configurations and third-party oversight.^[17] In the 2010s and 2020s, protocols evolved to accommodate advancements in vessel technology, incorporating provisions for dynamic positioning (DP) systems and electric propulsion. ITTC and classification society updates, such as those from the American Bureau of Shipping in 2018, addressed thruster interactions in DP configurations during bollard pull assessments, ensuring tests account for multi-propulsor setups and zero-speed static pulls under controlled power allocation.^[18] For electric and hybrid tugs, recent certifications—exemplified by guidelines in the 2019 International Standard—require documentation of propulsion modes (e.g., battery-assisted or full electric), with trials verifying sustained pull under variable power sources to reflect operational realities in emission-regulated ports.^[17] These adaptations have enabled certification of high-performance vessels, such as electric tugs achieving over 50 tonnes of bollard pull, while maintaining the core emphasis on safety and verifiability.^[19]

Measurement Methods

Practical Trials

Practical trials for measuring bollard pull involve securing the vessel to a fixed strongpoint, such as a shore bollard, using a towing line attached at the vessel's designated towing point. A calibrated load cell is inserted between the towing line and the strongpoint to measure the tension generated by the propulsion system. The vessel's engines are then operated at full power, with the propeller fully loaded and the vessel at zero forward speed, to produce the maximum static pulling force. This setup ensures the measurement captures the thrust available for towing without forward motion interference.^[17] The test duration typically includes a steady-state phase of at least 5 minutes, during which data is recorded to determine both peak and average tension values, allowing for stabilization after initial transient effects. Trials are conducted in both forward and astern directions to assess bidirectional capabilities, with the continuous bollard pull defined as the average force over this period. Measurements are taken using dynamometers, such as digital hydraulic or tension load cells with a sampling rate of at least 1 Hz, connected to data loggers for precise recording of line tension, engine revolutions, and shaft power. Towing lines, such as wire ropes of sufficient length (typically 50 to 100 meters in practice), are used to position the vessel sufficiently far from the strongpoint—typically at least 50 times the propeller diameter—to avoid interference from the propeller wash.^[17]^[6] Optimal conditions for accurate results require calm water with minimal environmental disturbances: currents less than 0.5 knots from the bow or sides (or 0.3 knots from astern), wind speeds not exceeding 10 m/s, and significant wave heights below 0.5 meters. The water depth should be at least four times the propeller immersion depth within a radius of two ship lengths from the test site to prevent shallow-water effects. The vessel must be in a light ship condition or ballasted to approximate operational draft, with half-full fuel tanks and no cargo, ensuring the propeller is fully submerged and the hull is free of excessive fouling.^[17] For estimation purposes prior to testing, empirical formulas relate bollard pull in tonnes to the vessel's brake horsepower (BHP). For conventional fixed-pitch propellers, bollard pull approximates BHP / 100; for nozzled propellers, the factor increases to approximately 1.1–1.3 × BHP / 100, accounting for enhanced thrust efficiency. These approximations, derived from classification society guidelines, provide rough predictions but require full-scale trials for certification. For certification purposes, trials must be conducted under independent supervision, such as by a classification society, resulting in a certificate valid for 5 years.^[6] Safety protocols emphasize proper line tension management and emergency release systems, while post-trial corrections may adjust for minor deviations in line angle to maintain horizontal pull, though modern standards often forgo explicit adjustments for water salinity or temperature, recording these parameters instead for reference. Salinity affects propeller efficiency slightly (e.g., a 0.8% reduction in fresh water), but trials are preferably conducted in saltwater without correction. Temperature influences engine performance, with non-tropical conditions (<45°C air, <32°C water) recommended to align with design ratings.^[17]

Simulation and Modeling

Simulation and modeling of bollard pull employ scaled physical models and computational techniques to predict static thrust without conducting resource-intensive full-scale trials. These methods allow engineers to evaluate propulsion performance under controlled conditions, facilitating design iterations and performance forecasting for vessels like tugboats. Model testing in towing tanks utilizes geometrically scaled replicas of hulls and propellers to measure thrust at zero advance speed. These experiments are conducted in facilities equipped with dynamometers to quantify forces, with results extrapolated to full scale primarily using Froude's law of similitude, which preserves gravitational effects dominant in low-speed flows, though Reynolds number scaling addresses viscous influences in propeller wakes.^[20] Such tests, often at scales like 1:70, provide reliable predictions of bollard pull by simulating idealized conditions free from environmental variables.^[21] Computational fluid dynamics (CFD) simulations offer a virtual alternative, solving the Navier-Stokes equations via Reynolds-Averaged Navier-Stokes (RANS) models to capture propeller thrust, hull-induced resistance, and wake field interactions at static conditions. Tools like ANSYS FLUENT employ finite volume methods with turbulence models such as SST k-ω to model flow around nozzled propellers and hull appendages, enabling analysis of multi-propeller interactions on tugboats.^[22] These simulations account for zero-speed hydrodynamics, including thrust deduction from hull proximity, typically requiring meshes with millions of elements for convergence.^[23] Validation of these approaches involves direct comparison with full-scale or model-scale trial data, demonstrating accuracies within 5-10% for modern CFD tools in predicting bollard pull forces. For instance, RANS-based simulations of twin-propeller tugs have shown thrust predictions differing by less than 0.5% from experimental measurements under ideal conditions, while escort tug analyses exhibit hull resistance errors averaging 6% and maximum deviations up to 10%.^[22]^[23] Model tank results, scaled via Froude laws, similarly align closely with trials, confirming their utility for pre-construction verification.^[20] Since the 2010s, advancements have integrated artificial intelligence and machine learning with CFD and model data to optimize bollard pull in electric and azimuth thruster designs. Machine learning algorithms, trained on simulation datasets, enable multi-objective propeller optimization for enhanced thrust efficiency in azimuth configurations, reducing design cycles while targeting maximum static pull.^[24] These hybrid methods support electrification by predicting performance trade-offs in rim-driven azimuth thrusters, improving energy utilization for sustainable towing operations. Despite these capabilities, simulations face limitations in replicating full-scale inefficiencies such as biofouling, which introduces variable roughness and drag not standardly incorporated in baseline models. CFD predictions often assume clean surfaces, underestimating real-world thrust losses from marine growth on hulls and propellers by up to 20% in fouled conditions without specialized roughness modeling.^[25] Model tests similarly overlook long-term degradation, necessitating complementary empirical adjustments for operational accuracy.

Influencing Factors

Propulsion System Design

The bollard pull of a vessel exhibits a direct correlation with installed engine power, as greater horsepower enables higher thrust output from the propulsion system under static conditions.^[26] However, mechanical transmission components, including gearboxes and shafts, introduce efficiency losses that diminish the power delivered to the propeller, typically reducing effective output by 2-5% due to friction and hydrodynamic drag.^[27] These losses are particularly pronounced in high-power setups, where optimizing gear ratios and shaft alignment becomes essential to maximize bollard pull.^[28] Propeller type significantly influences bollard pull through variations in thrust generation and efficiency. Fixed-pitch propellers, favored in many tug designs for their robustness, deliver high static thrust at maximum engine speed, making them ideal for sustained pulling operations.^[29] Variable-pitch propellers, by contrast, allow blade angle adjustments to optimize load distribution, achieving comparable bollard pull to fixed-pitch designs while offering better versatility across speed ranges.^[30] Nozzle and ducting integrations further enhance these effects by channeling and accelerating water flow around the propeller blades, elevating thrust coefficients and increasing bollard pull by 20-40% relative to open configurations.^[2] This acceleration principle, rooted in 1980s advancements in tug propulsion, has become standard for low-speed, high-thrust applications.^[31] Thruster configurations determine not only the magnitude but also the directionality of bollard pull. Conventional thrusters, typically fixed propellers stern-mounted with rudders, provide reliable ahead thrust but yield only about 65% of that value astern due to reversed flow dynamics.^[32] Azimuth thrusters, featuring 360° rotatable pods, eliminate this asymmetry by maintaining full bollard pull in any direction, thus enhancing towing precision and safety.^[33] Voith-Schneider cycloidal propellers, with their vertical blade arrays, prioritize superior maneuverability while delivering robust bollard pull through instantaneous thrust vectoring, as evidenced in recent tugs achieving up to 70 tonnes.^[34] Electric propulsion systems surpass diesel counterparts in sustained bollard pull performance, leveraging electric motors' ability to provide full torque from standstill without the ramp-up delays inherent in combustion engines.^[35] This instant response minimizes power losses at zero speed, enabling higher peak outputs in compact designs. In 2024, the fully electric Damen RSD-E Tug 2513 Bu Tinah established a Guinness World Record with an average bollard pull of 78.2 tonnes, highlighting the scalability of electric configurations for modern harbor operations.^[36]

Hull and Environmental Effects

The hull form exerts a notable influence on bollard pull by generating resistance through the stern shape and appendages like rudders and brackets, which contribute to the thrust deduction fraction whereby a portion of propeller-generated thrust counters hull drag instead of yielding net pulling force. In model tests, this interaction is quantified via the thrust deduction fraction, with appendages introducing additional drag corrected by a scale effect factor (1 - β) typically ranging from 0.6 to 1.0 (often 0.75 for twin-screw vessels).^[11] Trim and draft further modulate performance by determining propeller immersion depth, essential for optimal thrust; inadequate immersion reduces effective output, prompting standards to mandate loading vessels to design draft during trials, while permitting trim by stern not exceeding 2% of the vessel's length to avoid significant deviations.^[37] ^[38] Water conditions introduce variability in bollard pull measurements, particularly in shallow depths where bank effects and restricted flow can diminish propeller efficiency, though these impacts remain minimal at zero forward speed due to low hydrodynamic sensitivity. Maritime guidelines recommend trial sites with depths exceeding 20 meters or at least twice the vessel's draft to minimize immersion issues and flow disturbances. Waves and currents add further inconsistency; significant wave heights above 0.5 meters or currents over 1 knot can skew results by altering effective thrust direction and magnitude, necessitating calm conditions for standardized testing.^[39] ^[8] ^[17] Environmental factors such as temperature and salinity primarily affect bollard pull by modifying water density and viscosity, which directly scale propeller thrust since thrust is proportional to fluid density in the relation T = K_T \rho n^2 D^4, where \rho is density. Seawater density, averaging 1025 kg/m³ at 3.47% salinity, yields approximately 2.5% higher thrust than freshwater (around 1000 kg/m³), while temperature shifts from 0°C to 30°C reduce density by up to 0.6%, correspondingly lowering thrust potential. These variations, though small individually, can compound to influence overall performance by several percent in differing operational waters.^[37] Biofouling from hull growth progressively erodes bollard pull efficiency by elevating frictional resistance and drag, thereby increasing the thrust deduction load on the propulsion system. Minor microfouling may reduce propulsive efficiency by 10-16%, escalating to 86% in severe macrofouling cases, which indirectly diminishes net static pull. To address this degradation, tug certifications require periodic bollard pull re-trials, often annually or after dry-docking, to verify sustained performance amid fouling accumulation.^[40] Standards for bollard pull assessment, including ITTC procedures for model validation, incorporate corrections mainly for skin friction and scale effects but emphasize controlled trial conditions over post-measurement adjustments for full-scale sea state or depth influences. International guidelines similarly prioritize recording environmental parameters like temperature without applying numerical corrections, ensuring measurements reflect baseline capabilities under ideal setups.^[11] ^[17]

Applications

Tugboat and Towing Operations

Bollard pull serves as a fundamental metric in tugboat and towing operations, quantifying the static pulling capacity essential for assisting large vessels in commercial maritime activities. In these contexts, tugs provide critical support during berthing, unberthing, and maneuvering in confined harbor spaces, where precise control prevents collisions and ensures safe navigation. The measure directly influences tug selection, operational planning, and compliance with international safety standards, enabling efficient handling of diverse vessel sizes from container ships to supertankers.^[1] Towing calculations for safe harbor maneuvers rely on determining the required bollard pull to counteract environmental forces acting on the assisted vessel. A common approach estimates this as required bollard pull = total environmental forces / efficiency (typically 0.7–0.9), where total forces include wind (based on projected area), current (based on submerged area and speed), and waves, incorporating losses from towline dynamics and tug propulsion. This ensures the tug can maintain control under moderate conditions, such as winds up to 15 m/s and currents of 0.5 m/s, preventing drift during operations. More detailed models expand this to include wave and current forces, with total required pull = (total resistance) / efficiency, as outlined in maritime engineering guidelines.^[41]^[4] In harbor assistance, tugs are classified by their bollard pull to match operational demands, with higher capacities assigned to larger vessels in busy ports. For instance, tugs exceeding 50 tonnes of bollard pull are standard for handling massive ships in major hubs like Singapore, where the port authority categorizes tugs as "x-big" for pulls above 45 tonnes to support ultra-large container vessels and tankers. Examples include the KST Passion (71 tonnes) and Maju 510 (71 tonnes), which facilitate routine berthing in this high-traffic environment, processing over 40 million TEUs annually as of 2024.^[42]^[43] Such classifications ensure redundancy and safety, often deploying multiple tugs for combined pull exceeding 100 tonnes in complex maneuvers.^[42] For emergency towing, particularly of ocean-going vessels like supertankers, the International Maritime Organization (IMO) mandates minimum bollard pull standards to enable station-keeping and controlled drifting under adverse conditions. Guidelines require tugs to achieve sufficient continuous bollard pull—typically at least 90–100 tonnes for large tows—to withstand winds of 20 m/s, waves up to 5 m significant height, and currents of 0.5 m/s, with towline breaking loads scaled accordingly (e.g., 2.0 × bollard pull for tugs over 90 tonnes). These requirements, detailed in IMO's Guidelines for Safe Ocean Towing, ensure tugs can execute salvage operations or relocate disabled vessels without risking environmental damage or crew safety.^[44] Recent advancements in the 2020s have seen electric tugs achieve record bollard pulls, enhancing sustainability in towing operations by reducing emissions while maintaining performance. In 2024, the Damen-built Bu Tinah, operated by SAFEEN Group, set a Guinness World Record with an average high peak bollard pull of 78.2 tonnes, the highest for a fully electric tug, during sea trials in the UAE. This zero-emission vessel, powered by batteries and delivering equivalent force to diesel counterparts, supports greener harbor assistance and emergency responses, aligning with global decarbonization goals in maritime logistics.^[45] Despite its utility, bollard pull has limitations in dynamic towing scenarios, where static measurements can overestimate effective pull, necessitating additional escort tugs for control. In high-speed or angled towing, such as indirect escorting of tankers at 10 knots, generated forces can exceed bollard pull by factors up to 2.0 due to hydrodynamic effects and towline geometry, potentially straining fittings beyond safe limits. This overestimation in operational (dynamic) conditions—versus static tests—often requires escort tugs to provide braking or steering forces, mitigating risks like grounding in restricted waters.^[46]^[47]

Non-Motorized and Specialized Craft

In amphibious and military craft, bollard pull evaluates the effectiveness of alternative propulsion systems like waterjets on tracked vehicles, critical for operations in varied terrains. Full-scale tests conducted in 2024 on a large amphibious tracked military vehicle equipped with two waterjet propulsors demonstrated thrust convergence with experimental data, achieving stable towing forces despite cavitation challenges at low cavitation numbers below 2.2; initial impact forces exceeded final towing values by 81.8%, highlighting the need for optimized nozzle configurations to maximize pull in zero-speed conditions. These evaluations, performed in controlled freshwater basins, underscore bollard pull's role in verifying propulsion reliability for defense applications beyond traditional maritime use.^[48] For small craft and yachts, bollard pull ratings guide the selection of auxiliary thrusters for precise docking and maneuvering, where even modest thrust levels enhance control in confined spaces. Bow thrusters, for example, are often rated such that a 1,000 horsepower unit delivers approximately 10 tons of bollard pull, scalable down for personal watercraft to support standards emphasizing low-speed lateral force without exceeding hull limits. Manufacturers like ZF provide azimuth thrusters optimized for yachts, balancing bollard pull with course stability in performance ranges from 100 to 2,500 kW.^[49]^[50] Specialized uses extend bollard pull to inland waterway push boats and icebreakers, where pull indicates capacity for barge handling or ice resistance. Inland push boats, such as those designed by John Bludworth Shipyard, achieve 13 metric tonnes of bollard pull with 1,280 brake horsepower, enabling efficient shallow-draft operations on rivers and canals. In icebreakers, high bollard pull supports emergency towing and ice-breaking; the BOTNICA, an icebreaker-offshore vessel, generates 105 tonnes via twin Azipod units, combining thrust with 15-knot free-running speed for Arctic missions. Adaptations for these low-power or niche systems involve simplified trials, such as reduced-scale load cells and shorter test durations, to focus on peak performance without full industrial setups.^[51]^[52]^[53]

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Design and control of hybrid power and propulsion systems for ...
May 15, 2017 · This paper classifies ship propulsion topologies into mechanical, electrical and hybrid propulsion, and power supply topologies into combustion, ...
[35]
SAFEEN Group Achieves Guinness World Record™️ for Tugboats
Nov 11, 2024 · With an average high peak pull of 78.2 tonnes, this achievement marks a global milestone and underscores the exceptional capabilities and ...
[36]
[PDF] Marine Propellers and propulsion (CARLTON)
... Propeller geometry. 31. 3.1. Frames of reference. 33. 3.2. Propeller reference ... Salinity. 53. 4.3. Water temperature. 54. 4.4. Viscosity. 55. 4.5. Vapour ...
[37]
[PDF] Bollard Pull Test Procedure
A bollard pull trial is a full scale test with a vessel to determine the horizontal towline force which the main propulsion systems can generate at a vessel ...Missing: salinity | Show results with:salinity
[38]
[PDF] Bollard Pull | HydroComp, Inc.
This requires a minor correction to the bollard pull thrust to deduct the boat's own drag from the calculated delivered thrust to determine the net useable ...
[39]
How biofouling impacts vessel efficiency — and how to fix it
Mar 8, 2021 · Biofouling increases drag, causing high fuel costs. Even minor microfouling can decrease efficiency by 10-16%, and macrofouling can cause 86% ...
[40]
Bollard Pull Calculations For Towing Operations | PDF - Scribd
Rating 3.7 (6) This document introduces how to calculate the required bollard pull for towing operations. It discusses that bollard pull calculations determine the size of ...
[41]
Towage | Maritime & Port Authority of Singapore (MPA)
Tug usage guidelines for vessel movements in the Port of Singapore. · 10 to 16 tonnes bollard pull = small tug · 17 to 24 tonnes bollard pull = medium tug · 25 to ...Missing: examples | Show results with:examples
[42]
[PDF] IMO – Guidelines for Safe Ocean Towing
Dec 21, 1998 · 2.0 times the tow line MBL, for tugs with bollard pull less than 50 tonnes;. -. 1.5 times the tow line MBL, for tugs with bollard pull greater ...Missing: going supertankers
[43]
SAFEEN Group's electric tug wins Guinness World Records title
Nov 11, 2024 · With an average high peak pull of 78.2 tonnes, the achievement marks a global milestone, AD Ports Group said, noting that this all-electric ...
[44]
White Paper: The Challenge of Tanker Escort Towing - ABPmer
Nov 12, 2024 · Tanker vessel equipment used for active escort towing can be subject to forces significantly greater than static bollard pull of the tug when undertaking ...
[45]
[PDF] GUIDELINES FOR SAFE HARBOUR TOWAGE OPERATIONS
LIMITATIONS OF TUGS. The tug's Bollard Pull. STATIC BOLLARD PULL and OPERATIONAL (Dynamic) BOLLARD PULL: The Bollard pull of a tug only refers to the static ...
[46]
TP 15491 – Small Vessel Compliance Program - Tug Guidance ...
Aug 21, 2024 · The purpose of this Guideline is to assist the owners of small tugs of not more than 15 gross tonnage to complete their Small Vessel Detailed Compliance Report.
[47]
Bollard Pull and Self-Propulsion Performance of a Waterjet ... - MDPI
Oct 17, 2024 · This paper describes the unique full-scale bollard pull and self-propulsion tests of a large amphibious tracked military vehicle with two waterjet propulsors.
[48]
Thrusters | Ship Handling
So A bow Thruster of 1000 HP = 746 KW = 10 tons Bollard pull. Bow Thruster of 5000 HP = 3730 KW = 50 tons Bollard pull. As we can see above to get power ...Missing: yachts | Show results with:yachts
[49]
Well Mounted Azimuth Thrusters - ZF
The propulsion system can be optimized for speed or bollard pull. The thruster can be delivered in a performance range of 100-2,500 kW. The thruster can be ...Missing: AI | Show results with:AI
[50]
Inland Push Boats - Signet Maritime Corporation
BOLLARD PULL, 13 Metric Tonnes ; HORSEPOWER, 1,280 BHP ; DESIGNER, John Bludworth Shipyard, LLC, Corpus Christi, TX, USA ; BUILT, 2007, John Bludworth Shipyard, ...
[51]
Icebreaker/offshore vessel BOTNICA - Wärtsilä
The latest technology has been incorporated and BOTNICA is notable for two Azipod units which provide a bollard pull of 105t and a free running speed of 15 ...