Ultra Large Container Research Articles

Analysis of the overall structural strength and optimization recommendations for ultra-large container ships based on the improved equivalent design wave method

Ultra-large container ships face challenges in structural strength under complex sea conditions. The traditional equivalent design wave method inadequately considers nonlinear wave effects, leading to inaccuracies in strength assessments. This article improves the method by incorporating nonlinear wave effects and optimizing wave spectrum parameters to better simulate structural responses. A study on a container ship, using refined wave load calculations and finite element analysis, focusing on stress distribution in critical hull areas. The findings show that the enhanced method more accurately reflects real loading conditions, confirming the ship’s structural soundness and offering optimization suggestions for improved safety and longevity.

Coupling a time-domain code with a RANS solver for slamming analysis

ABSTRACT A time domain hydroelastic code (TD) based on strip theory is two-way coupled with a Reynolds Averaged Navier−Stokes (RANS) solver to capture the bottom slamming effects on ships. The study is conducted on an Ultra Large Container Ship (ULCS). The methodology considers the hull’s flexibility and analyses longitudinal bending in head seas. Ship motions are calculated using a body non-linear time-domain method based on strip theory. The equations of motion are solved, and time integration is performed using the fourth-order Runge–Kutta method. When a slamming event is identified, the TD code activates a RANS solver to determine the bottom slamming force. The simulations are conducted under extreme sea conditions, and the hull experiences springing and whipping responses. The numerical results of vertical bending moments are compared with experimental data. The bottom and bow flare slamming are identified from the simulations.

Towards a reliable method for extrapolation of propulsion performance for vessels with twin-crp-pod system

The study presents power performance prediction of an Ultra Large Container Ship (ULCS) with hybrid twin-crp-pod propulsion system. Twin crp-pod propulsion system is a combination of three concepts: twin screw, contra-rotating propellers (crp) and conventional shaft propellers with pod propulsors behind. The presented study shows the current extrapolation method for crp propulsion systems and tries to point out its weaknesses. As a case study, a 400 m ULCS has been investigated in full-scale and in model scales of 24 and 37.416. The analyses were carried out for all scales with use of CFD numerical methods and for the scale of 37.416 based on towing tank tests. All the results have been extrapolated with the same method and results have been compared. The investigations clearly show differences in delivered power prediction extrapolated from towing tank results giving the maximum value and from CFD made to scale of 24 the minimum value. Finally, conclusions on possible sources of differences, including the numerical and analytical methods are presented.

Analysis of empirical method for predicting maneuverability of ultra-large container ship using Maneuvering Modelling Group (MMG) model

Analysis of empirical method for predicting maneuverability of ultra-large container ship using Maneuvering Modelling Group (MMG) model

Effects of design and fabrication of segmented ship models on test results of wave-induced loads

The design and fabrication of segmented ship models have great effects on wave-induced loads in wave basins. Three different segmented ship models of a 20,000 TEU (twenty-feet equivalent unit) ultra-large container ship are designed and fabricated with different support frames and backbones. The shell and wooden frames of Models A and B were fabricated with the same method, however, the type of backbone and scale are different. Model C is a steel framing model, the dimensions of the frame members are validated by finite element method and the frame members are connected with welding technique. Suitable parameters are selected to design and fabricate Model C with the improved fabrication method. The calculated mode results of Model C are compared with the experimental data to validate the reasonability and advantage of the improved design and fabrication method. The dry and wet modes of the three ship models are measured and compared. The three different ship models are tested under typical conditions in different wave basins, and the corresponding test results are compared to reveal the effects of the fabrication method on structural elastic modes and wave-induced loads. Finally, the uncertainty analysis of the three model tests under typical conditions are conducted.

Techno-economic analysis of onboard CO[formula omitted] capture for ultra-large container ships

Decarbonising the naval shipping sector is of paramount importance to decrease global CO2 emissions. This work presents a techno-economic analysis of onboard solvent-based carbon capture for an ultra-large container ship, powered by two dual-fuel engines fed with either heavy fuel oil or liquefied natural gas. Different case studies are proposed depending on the fuel used by the ship and on the chosen design to supply the necessary heat and electricity to the carbon capture unit. Aside a conventional strategy based on heat provided via fuel combustion in a boiler, a novel configuration based on electric heat pump is investigated. The economic analysis is based on a real inter-continental journey. The results highlight that onboard carbon capture determines an increase in fuel consumption with respect to the unabated ship, that varies depending on the exhaust gas CO2 content (hence, on the ship fuel) and on the selected process design. The integration of the electric heat pump leads to a significant decrease in this additional fuel consumption and better results in terms of CO2 avoidance and costs. The carbon abatement cost is found in the range of 64–149 €/t of CO2 avoided.

Brittle Crack Arrest Temperature Estimation Method Utilizing a Small-Scale Test with a Thick Steel Plate for Shipbuilding

As the shipbuilding industry has emerged from an extended recession, orders for high-value-added ships, such as LNG and ultra-large container ships, are increasing. For ultra-large container ships, high-strength, thick materials are applied. Because the possibility of brittle fracture increases owing to the application of thick steel plates, the related regulations of the International Association of Classification Societies have been strengthened to prevent brittle fracture. To secure brittle fracture stability, it is necessary to secure crack arrest toughness (Kca) through large ESSO experiments or to secure a crack arrest temperature (CAT) value. Because large-scale experiments require considerable costs and efforts, efforts have increased to examine brittle fracture stability through small-scale tests. In the present study, a technology was developed to predict CAT with small specimens. The CAT prediction formula developed with small specimens makes it possible to accurately predict CAT using data obtained through large-scale experiments.

Numerical method for whipping response of ultra large container ships under asymmetric slamming in regular waves

In this paper, a 3-D nonlinear time-domain hydroelastic analysis method for ship wave loads considering asymmetric slamming is proposed, and a 3-D Rankine panel method is used to solve the seakeeping problem. To accurately predict the hydroelastic response of the hull girder, the interaction between the hull structure and the flow field is considered in the body boundary condition. The motions and sectional loads of the ship are expressed by the superposition of the modal, which is obtained by modal analysis on a 3-D finite element model of the hull. After calculating asymmetric slamming loads using the Modified Logvinovich Model (MLM), the hydroelastic response of a 21,000-TEU container ship is analyzed, which incorporates the horizontal bending-torsional coupling vibration. Furthermore, the hull motion, slamming force, and section load are analyzed in detail to properly identify the mechanism of the slamming-whipping phenomenon. The results show that asymmetric slamming significantly affects the horizontal-torsional whipping response of the hull, especially when the wave encounter frequency matches the natural frequency.

Hydroelastic effects on the vertical bending moment of a container ship in head and oblique seas

Large-sized ships like Ultra large container ships (ULCS) experience severe hydroelastic vibrations like springing and whipping. This study numerically investigates the performance of a time domain method to assess the effect of structural vibration in calculating of vertical bending load of an ULCS. The proposed 2-D body nonlinear time-domain numerical method comprises a seakeeping solver based on potential flow theory and a structural solver based on Timoshenko beam theory. The simulations are carried out in the head and oblique waves for various forward speed conditions. The solver captures the effects of high-order springing and whipping in vertical bending. The numerical method identifies the whipping effect based on the slamming associated with the relative motion of the ship. The vertical bending moment is calculated in both regular and irregular waves, and the results are compared with the experimental results. The statistical evaluations of available results for irregular waves are carried out and presented. The numerical results are in good agreement with the experimental ones for most of the analyzed cases.

Rapid acquisition method for structural strength evaluation stresses of the ship digital twin model

The existing ship hull structure stress monitoring can only give the stress state of typical measuring points, but the monitoring point may not be the most dangerous location of the ship hull structure. To solve this problem, this paper carried out the research of ship strength digital twin. Concretely, to meet the real-time requirements for obtaining the structural stress state, this paper proposed a rapid acquisition method for structural strength evaluation stresses of the ship digital twin model, which realizes the rapid acquisition for structural yield strength evaluation stresses at the monitoring point and the non-monitoring point. To illustrate the specific application and application effect of the proposed method, the amidships three compartments section of a 21,000TEU ultra-large container ship was selected as the research object. And the case that this research object may suffer from the vertical wave bending moment and the horizontal wave bending moment simultaneously was considered. Related studies show that the proposed method can accurately recognize the load actually suffered by the ship monitoring structure. And the specific meaning of the ship monitoring structure referred to here is the ship hull structure that requires structural stress state monitoring. At the same time, related studies also show that the maximum error of the calculation results obtained by the proposed method does not exceed 0.0005% in obtaining the structural yield strength evaluation stress at the monitoring point, while the maximum calculation error does not exceed 0.032% in obtaining the structural yield strength evaluation stress at the non-monitoring point.

A proposed design for 5-G fire detecting and extinguishing system: ultra-large container ship case study

ABSTRACT The containerized cargo volume reaches 168.2 million TEU. There have recently been a staggering number of fire catastrophes onboard container ships. Investigations have identified that a rapidly developing fire is one of the main challenges in container fires. On the other hand, firefighting regulations had disregarded container vessel capacity increase. The resulting financial losses and environmental catastrophes paid astronomical bills. This research elaborates on an innovative solution utilizing a 5 G wireless self-detecting and extinguishing fire-control system. The system was applied in a case study of 19,870 TEU ultra large-container ships; The results demonstrate the number and locations of the system components. The system can reduce human interference with the fires onboard. The feasibility analysis output shows a low initial cost compared to the losses of such incidents. Moreover, the time of radio spectrum signals of the proposed system is high speed; remarkably, the internal container monitoring needs around 30 seconds to detect heat and another few seconds to activate the CO2 and smother the suspicious container in its early intuition with allocation bothered alarm. The firefighting improvement technology could be a promising solution for monitoring and controlling dangerous cargo containers fire.

Analysis of the Mooring Effects of Future Ultra-Large Container Vessels (ULCV) on Port Infrastructures

The size of container vessels is continuously growing, always exceeding expectations. Port authorities and terminals need to constantly adapt and face challenges related to maritime infrastructure, equipment, and operations, as these are the principal areas affected by the future Ultra Large Container Vessels (ULCVs). Maneuvring areas are at their limits, and mooring equipment is at an increased risk of being overloaded. This study aims to analyze the limitations that present mooring systems may face when ULCVs are subjected to wind and passing-ship forces exerted by a future ULCV and wind forces through Dynamic Mooring Analysis (DMA). A hypothetical and massive future ULCV with a capacity of 40,000 TEU is compared to the Emma Maersk, which is a present vessel that regularly calls at container terminals. The Emma Maersk, with its current mooring arrangement, experiences higher motion than future ULCVs, which experience higher forces but are also moored with more and stronger lines. This translates into considerably higher loads in the mooring system, potentially compromising safe mooring conditions at the terminal. Mitigating measures are proposed in the study to face these limitations. In addition, the study explores the potential of new and innovative mooring technologies, such as high-strength synthetic ropes and smart mooring systems, to address the challenges posed by ULCVs. A container terminal at the Port of Rotterdam, Europe’s largest sea port, has been analyzed as a case study. The terminal is located next to a busy fairway that leads to other container terminals, justifying the need to analyze both wind and passing-ship effects on moored ships.

Errata: Communications - Scientific letters of the University of Zilina, 2022, 24(3), p. B228-B238, https://doi.org/10.26552/com.C.2022.3.B228-B238, Prediction of the ultra-large container ships' propulsion power at the initial design stage

Errata: Communications - Scientific letters of the University of Zilina, 2022, 24(3), p. B228-B238, https://doi.org/10.26552/com.C.2022.3.B228-B238, Prediction of the ultra-large container ships' propulsion power at the initial design stage

Prioritizing management of high-risk routes and ports by vessel type to improve marine biosecurity efforts

The shipping industry constitutes the main vector of marine bioinvasions. Over 90,000 vessels world-wide create a highly complex shipping network that requires appropriate management tools. Here we characterized a novel vessel category, Ultra Large Container Vessels (ULCV), in terms of potential contribution to the dispersal of Non-Indigenous Species (NIS) in comparison to smaller vessels traveling similar routes. Such approach is essential for providing precise information-based risk analysis necessary to enforce biosecurity regulations and reduce the adverse global effects of marine NIS. We used Automatic Identification System (AIS) based websites to extract shipping data that will enable us to test for differences in two vessel behaviors linked to NIS dispersal: port visit durations and voyage sailing times. We then examined the geographic spread of ULCVs and small vessels, quantifying the accumulation of new port visits, countries, and ecoregions for each vessel category. Finally, Higher Order Network (HON) analysis revealed emergent patterns within shipping traffic, species flow, and invasion risk networks of these two categories. Compared to the smaller vessels, ULCVs spent significantly longer time in 20% of the ports and were more geographically constrained, with fewer port visits, countries, and regions. HON analysis revealed that the ULCV shipping species flow and invasion risk networks were more similar to each other than to those of the smaller vessels. However, HON port importance shifts were discernible for both vessel categories, with major shipping hubs not necessarily being major invasion hubs. Overall, compared to smaller vessels, ULCVs behave differently in ways that potentially increase biofouling risk, albeit in a smaller set of ports. Future studies using HON analysis of other dispersal vectors appears critical for prioritizing management of high-risk routes and ports.

Investigation on time-domain simulation and experiment of harmonic rolling of ultra-large container ship in waves

When an accident due to harmonic rolling occurs, loss will be huge, especially for ultra-large container ships (ULCS). In the paper, the time-domain method is adopted to study and analyze the occurrence of non-linear harmonic rolling phenomenon of ULCS and subsequent motion behaviors. Under the weakly scattering hypothesis, six-degree-of freedom(6-DOF) time-domain ship motion equation is established by employing impulse response function. The incidental wave force and the restoring force are obtained by pressure integrating on instantaneous wet surface, while the roll damping coefficient is obtained by experiment. An ULCS navigating in regular waves of various frequencies is numerically simulated and investigated by model tests. The characteristics and mechanism of harmonic rolling of the ship with different metacenter-heights, which sails in head and following waves of different periods, are studied and analyzed. The result comparison shows that the time-domain method used in the paper can predict the occurrence and motion amplitude of the harmonic rolling very well. Although the seaworthiness of ULCS is generally better than smaller ships, there is still the possibility of triggering the problem of harmonic rolling in real sea navigation. Thus, it is necessary to study and analyze during ship design.

Assessment Of Alternative Marine Fuels from Environmental, Technical, and Economic Perspectives Onboard Ultra Large Container Ship

Ship emissions reduction targets are pushing the maritime industry towards more sustainable and cleaner energy solutions. Marine fuels play a major role in this because of the emissions resulting from the combustion process associated with the prime mover(s), therefore, one of the technical solutions is to replace conventional marine fuels with cleaner fuels. Hence the aim of this study is to undertake environmental, technical, and economic analysis of alternative fuels to reduce the environmental footprint and lifetime costs of the long-distance shipping sector. As a case study, an ultra large container ship operating on the East-West trade route has been considered, and the analysis focus ed on natural gas and methanol as alternative fuels. This study adopted three approaches : environmental, technical, and economic methods to compare the alternative fuels with the conventional ones. The results showed that a dual-fuel engine operated by natural gas will reduce CO2, SOx, and NOx emissions by 28%, 98% and 85%, respectively , when compared with emission values for a diesel-powered engine. Furthermore, the reduction percentages reach 7%, 95% and 80% when using a dual-fuel engine operated by methanol, respectively. The proposed dual-fuel engines will improve the ship energy efficiency index by 26% and 7%, respectively. The study shows that methanol is the most economical alternative fuel for this container ship, replacing diesel with methanol, leads to a power system that is only 30% more expensive than the existing one. The analysis confirms that the cost of fuel has a major effect on the ship’s life cycle cost and that by reducing the fuel costs, the costs of the power system become more acceptable.

Shipping voyage simulation reveals abiotic barriers to marine bioinvasions.

The shipping industry is considered the main vector of introduction of marine non-indigenous species (NIS). NIS distributions are often a consequence of frequent trade activities that are affected by economic trends. A dominant trend in the shipping industry is the operation of Ultra Large Container Vessels (ULCV), which are over 395 m long and sail mostly on the East-Asia - northern-Europe route. Understanding the risk of NIS introduction by this emerging shipping category is needed for devising strategies for sustainable shipping. Here, we conducted a controlled simulation of key abiotic factors that determine marine bioinvasion success: temperature, salinity, and food availability along selected routes, under two treatments: ULCV and intermediate-size vessels. We tested the effect of each treatment and the varying environmental conditions on the survival of two invasive ascidians (Chordata, Ascidiacea). We used survival analysis methods to locate predictors of ascidian mortality; Environmental conditions at ports with high mortality were used to identify similar major ports on a global scale as potential abiotic barriers. The key factors in ascidian mortality varied between the two species, but for both species, the treatment and salinity were dominant predictors for survival. We identified Port Klang, Rotterdam, and Dammam as ports with high mortality and located several globally distributed major ports that present similar environmental conditions. Our results highlight the potential role of selected major ports as abiotic barriers to fouling organisms during ocean voyages. The tolerance of the tropical-origin Microcosmus exasperatus to the northern-Europe conditions, and of the temperate/sub-tropical origin Styela plicata, to high temperature conditions, point out the urgent need to modify international fouling regulations in view of global change. Further studies on the survival of fouling organisms during a cascade of changing environmental conditions will contribute to the advancement of science-based regulations to reduce the adverse effects of NIS.

Predviđanje kapaciteta proizvodnje električne energije velikih i vrlo velikih kontejnerskih brodova u početnoj fazi dizajna

Container ships represent the fastest growing segment of global shipping. Tackling such challenges as the constant pursuit of reduction of unit transportation costs and negative effects on the environment has led to the development of very- and ultra-large container ships, which dominate transport on the world's major shipping routes. Very-large container ships are conventionally assumed to have a cargo capacity above 10,000 TEU and an overall hull length below 369 meters, whilst the unique feature of ultra-large container ships is an overall hull length over 390 meters. The ship operational states and the main electric power receivers such as reefers and bow thrusters are mentioned and formulae to predict their electricity demand are given. Contemporary configurations of ships’ electric power stations are presented and discussed. Cargo capacity expressed in 20-foot equivalent units (TEU) was identified as the main predictor of the electricity generation capacity based on a representative very- and ultra-large container ships database. Using a simple linear regression model based on the least squares method, a formula was developed to predict the electricity generation capacity of very- and ultra-large container ships at the initial design stage. The prediction will find application in the design of very and ultra-large container ships’ electric power stations. The use of the developed formula at the initial design stage enables obtaining results that are sufficiently accurate to the results of the exact verification calculations at the technical design stage.

Mega Vessels – Mega Error?

Does it actually make sense to further increase the size of Ultra Large Container Ships from the shipping line’s perspective? Is possibly the opposite of what the growth in size is actually supposed to achieve experienced with the current ship sizes? These questions are followed up on the basis of some fundamental geometric and physical considerations, whereby the focus is on the effects of the longer port stays of the ever larger ships. Based on proportionalities a simple equation for a Fuel/TEU Indicator is introduced to determine the optimum ship size with regard to the fuel quantity and the carbon footprint per TEU for a particular liner service. This is complemented by a Total Cost Indicator for estimating the general optimum ship size. The literature published so far has meanwhile identified doubts on the overall economy of these ships especially when related land based costs are also taken into account but still acknowledge economies of scale effects for the ever growing ships themselves. This paper is intended to scrutinize this thesis.

Prediction of the Ultra-Large Container Ships' Propulsion Power at the Initial Design Stage

Container ships represent the fastest growing segment of maritime transport. The need to reduce unit transportation costs and environmental impact has led to development of the most capacious ultra-large container ships operating on the world's major shipping routes. A representative database of ultra-large container ships was created and further subdivided according to the main technical parameters. Using a simple cubic regression model, based on the least squares method, an equation, compliant to the general propeller law, was developed to predict the propulsion power of ultra-large container ships as a function of their sailing speed. The results obtained using the developed equation should be sufficiently close to the results of the exact verification calculations at the technical design stage. Then this prediction would find application in the design of both main propulsion, as well as waste heat and cold recovery systems.