Pure Car Carrier Research Articles

Comparison of stochastic stability boundaries for parametrically forced systems with application to ship rolling motion

Numerous accidents caused by parametric rolling have been reported on container ships and pure car carriers (PCCs). Considering this dangerous phenomenon, the parametric rolling in irregular seas is examined in this paper based on the stability of the systems origin, which corresponds to the upright condition of the vessel. It provides a novel theoretical explanation of the instability mechanism for two cases: white-noise parametric excitation and colored-noise parametric excitation. Moreover, the authors confirm the usefulness of the previously provided formulae by Roberts and Dostal by means of numerical examples.

부품 공급망 위험이 공급사슬과 해운 분야에 미치는 영향

Of late, various risk factors, such as the closure of container ports due to the COVID-19 pandemic, decline in container fleets, and instability in final demand, have had a detrimental impact on the business environment. Such negative effects could prevent companies from achieving their goals. Therefore, it is necessary to identify the risk and implement appropriate risk management strategies based on the impact factors of the risk. This study analyzed the impact of supply chain risks on the domestic automobile production network and maritime car carrier market. We quantified supply chain risks that arise in domestic automobile production processes and employed the vector auto regression models to analyze the effects of these risks on the automobile supply chain and pure car carrier market. In addition, using impact reaction function, we analyzed the process through which the risk in the supply chain extends to automobile production and pure car carrier market. It is expected that this study will help set long-term and short-term targets for production plans and demarcate corporate strategies through effective response to market conditions.

Investigating the determinants of shipowners’ emission abatement solutions for newbuilding vessels

• We identify the determinants of the owners’ abatement choice for newbuilding ships. • Vessel type plays a critical role in the shipowners’ abatement solutions. • The shipowners from different countries exhibit a unique abatement preference. • The Sulfur Cap has triggered demand for scrubber but not alternative fuel. • The influence of bunker cost for abatement solutions of new vessels is pretty weak. Because of the long lifetime of newbuilding vessels, shipowners' emission abatement solutions will have a profound impact on the greening transition of the shipping industry. A multinominal logit model is developed to identify the key determinants that affect the shipowners' choice of the solutions. New findings include: (1) Alternative fuels (e.g. liquefied natural gas) are the most attractive choice for gas ships and pure car carriers; and dry bulk ships and crude tankers prefer to use low-sulfur fuels. (2) Singaporean and Japanese shipowners are more likely to adopt the alternative fuels. (3) The IMO 2020 cap has significantly affected shipowners’ preference for scrubbers but not for alternative fuels. It is well known that economic factors affecting a shipowner’s decisions include freight rate and bunker cost but these factors weakly influence the emission abatement solution choice for new ships. This research provides helpful insights for the policymaker to guide shipowners to invest in more eco-friendly vessels and assist various stakeholders in forming efficient decisions.

Steady sailing performance of a ship in the proximity to the bank under windy conditions

This paper presents a method to efficiently calculate steady sailing conditions such as check helm, speed drop, hull drift angle, etc. of a ship moving in parallel to a bank wall under steady wind, together with the course stability at the equilibrium condition. Using this method, this study investigates the bank effect on the steady sailing condition and the course stability of a pure car carrier in steady wind and it evaluates the limiting wind condition for safe navigation (maneuvering limit). In case of head wind, a significant speed drop appears. In case of oblique head wind from the port side, the hull drift angle increases significantly and there is a distinct possibility that the ship touches the bank wall. In case of oblique following wind from the port side, the check helm increases significantly, because the wind force is added to the bank suction force. This becomes critical when the ship moves closer to the bank and in more shallow water areas, and the maneuvering limit level becomes more severe. The present method is a useful tool for measuring the maneuvering limit of a ship moving in close proximity to the bank under steady wind.

Characteristics of Roll Damping of Pure Car Carrier and Liquefied Natural Gas Carrier and applicability of Ikeda’s Method

Characteristics of Roll Damping of Pure Car Carrier and Liquefied Natural Gas Carrier and applicability of Ikeda’s Method

Maneuvering hydrodynamic derivatives and course stability of a ship close to a bank

Captive model tests are conducted for a pure car carrier in the proximity of a sloped bank with variations in water depth, distance between ship hull and bank, hull drift angle and heel angle. Using the hydrodynamic derivatives obtained, the check helm and hull drift angle required at equilibrium conditions are estimated. Course stability of the ship sailing in the proximity of the bank is also studied based on a simplified analysis method. In h∕d=1.2 where h∕d means ratio of water depth h to ship draft d, the check helm of the ship reaches 35° near η0∕L=0.27 where η0 is the distance between the ship center line and the bank. Although this ship is course unstable in case of no rudder control, the ship becomes course stable in any water depths by employing the autopilot with appropriate control gains. The present analysis method is useful for conventionally assessing the course stability of a ship in the proximity of a bank.

Application of the MMG method for the prediction of steady sailing condition and course stability of a ship under external disturbances

For the navigation safety of ships, it is essential to monitor the maneuvering characteristics under external disturbances due to wind and waves. For this purpose, evaluating the average steady sailing conditions such as check helm, speed drop, hull drift angle, etc. of a ship moving straight in steady wind and waves is beneficial. In addition, the dynamic stability (course stability) of the ship should be evaluated under its steady sailing condition. This study proposes a method for predicting the steady sailing conditions and course stability under external disturbances, based on the MMG standard method presented by Yasukawa and Yoshimura (J Mar Sci Technol 20(1):37–52, 2015). The calculation accuracy of the MMG method has been validated through experiments. The steady sailing conditions and the course stability of a pure car carrier are calculated using the proposed method under external disturbances in deep and shallow waters. In addition, the environmental conditions that limit safe navigation (maneuvering limit) are also discussed, while investigating the effect of the main engine output in particular. In both deep and shallow waters, a significant effect on the maneuvering limit is observed due to a reduction in engine output. Thus, the presented method is useful in capturing the maneuvering limit of the ship under external disturbances.

Manoeuvrability in adverse conditions: Case studies

Introduction of the Energy Efficiency Design Index (EEDI) raised concerns that ship designers may simply reduce the installed power to satisfy EEDI requirements. To address the problem by in-depth research, EU-funded project SHOPERA (Energy Efficient Safe SHip OPERAtion) developed criteria and acceptance standards for the assessment of sufficiency of propulsion and steering systems of ships for manoeuvrability in adverse conditions. Here, their impact on ships of all types in the EEDI framework is investigated and compared with the statistics of relevant accidents collected in SHOPERA. The comparison shows that the proposed standards seem appropriate for tankers, RoRo cargo vessels, pure car carriers and gas carriers, whereas for small bulk carriers and small general cargo vessels, stricter standards may be needed if the same safety level is targeted for small ships as for large ones. The results also show that ships of almost all types studied can satisfy the proposed standards together with the EEDI phase 3 requirements, excepting bulk carriers and tankers, which can satisfy the proposed standards and EEDI phase 2 requirements but not those of phase 3. For RoRo passenger ships, satisfying the EEDI phase 3 requirements alone may be problematic because of other limitations concerning design and operation.

Practical maneuvering simulation method of ships considering the roll-coupling effect

In this study, a practical maneuvering simulation method is presented considering the roll-coupling effect by extending an ordinal simulation model (3D-MMG model) proposed by Yasukawa and Yoshimura (J Mar Sci Technol 20:37–52, 2015), and adding the motion equation of roll. The roll moment acting on the hull is estimated by multiplying the hull lateral force with the vertical acting point. With respect to the surge force, lateral force, and yaw moment, the derivative expression model is employed. Subsequently, hydrodynamic derivatives with the exception of the roll-related terms are obtained by a captive model test based on the 3D-MMG model. The roll-related derivatives and the vertical acting point of the hull lateral force are estimated by simple formulae constructed based on the experimental data of four ship models. To validate the proposed simulation method, turning simulations are conducted for a pure car carrier model with variations in the metacentric height $${\overline{\mathrm{GM}}}$$ and are compared with free-running model test results. The simulation method exhibits sufficient accuracy with respect to its practical use and is useful to conventionally predict turning motions by considering the roll-coupling effect.

The evaluating on EEDI and fuel consumption of an inland river 800PCC integrated with solar photovoltaic system

ABSTRACT In recent years, the inland river shipping industry in China has been facing the pressure to comply with ‘low carbon shipping’ policies. Solar energy as one of the most widely used new energy sources has attracted more and more attention in the shipping industry. In 2015, the researchers from Wuhan University of Technology have successfully applied solar energy in an inland river 800PCC (Pure Car Carrier) – ‘Anji204’. The present article described the photovoltaic (PV) generation system which was installed on board the ship and reported the results of actual navigation trials on the testing leg, Yangtze River. On the basis of the collected data, the main research purpose is to evaluate the greenhouse gas (GHG) emission and fuel consumption after introduced solar energy into ship energy system by using Energy Efficiency Design Index (EEDI) analysis. The results show that the ship EEDI reduced from 55.09 g_CO2/ton·nmile to 52.02 g_CO2/ton·nmile, decreased by about 5.57%. In addition, it can reduce the fuel consumption by an average about 16 tons per year. Therefore, the utilisation of solar energy in ships can help the inland river shipping industry to meet the ‘low carbon shipping’ policies.

Numerical Analysis of Hydrogen Dispersion in Wind Tunnel Modeled on Vehicle Space of Pure Car Carriers

Seaborne transportation of hydrogen fuel cell vehicles (HFCVs) by pure car carriers is highly expected to increase due to rising demand for environmental protection in the world. When hydrogen leaks from a HFCV, it may accumulate near the ceiling of a vehicle space, since stiffening members referred to as longitudinal girder, web beams and longitudinal frames act as so-called “smoke barriers”. When carrying out safety assessment of the carriage of HFCVs with possible hydrogen leakage, it is necessary to validate numerical simulation tools to accurately predict ventilation flow properties and hydrogen behavior near the ceiling of a vehicle space. For this purpose, large-eddy simulation (LES) on ventilation flow and hydrogen dispersion in a wind tunnel has been carried out using Fire Dynamics Simulator (FDS), which is one of the well-validated computational fluid dynamics (CFD) codes. The sensitivities of computational grid size and subgrid-scale (SGS) models in the LES technique have been investigated by comparing measurement data. The results indicated that when ventilating the wind tunnel without releasing hydrogen, the present CFD calculations could reproduce the measurement data on velocity profiles without dependence on the SGS models by assigning more than about 10 computational grids to the “smoke barriers” in the depth direction. On the other hand, in the case of ventilation with releasing hydrogen, numerical results with the same grid size considerably underestimated experimental data on hydrogen concentrations. Therefore, care should be taken for the interpretation of real-scale simulation results with relatively coarse, computational grids. The present numerical results also point to a need to improve SGS models in such a way that the effects of stratification of hydrogen/air mixture due to buoyancy can be taken into consideration.

Emergency Unberthing without Tug Assistance

Shipmasters may have to perform unberthing without tugboat assistance when a tsunami warning is issued. Keeping this in mind, the authors studied emergency unberthing without tug assistance by conducting numerical simulations and full-mission ship maneuvering simulator (SMS) experiments. A panamax class medium-sized bulker and a pure car carrier (PCC) were used as test ships. In the experiments, they established the limitations of basic shiphandling techniques such as stern kick out, backing, and accelerating turn in windy conditions using a mathematical modeling group (MMG)-type mathematical maneuvering model. On the basis of the results, they produced a shiphandling scenario and evaluated it using SMS experiments. They concluded that unberthing without tug assistance in 5 m/s onshore winds is possible. Furthermore, the use of thrusters can greatly reduce the time required for unberthing.

Study on Welding Distortion of Stiffened Thin-Plate Structures Using Idealized Explicit FEM

In this research, to evaluate the welding distortion of stiffened thin-plate structures, an analysis method was developed that considers large deformation theory in elastic analysis using inherent strain based on Idealized Explicit FEM with shell elements. The developed method was applied to the analysis of stiffened thin-plate structures. The following factors were considered in the analysis to investigate their influence on welding distortion: heat input and welding processes such as double-sided continuous fillet welding, single-sided continuous fillet welding, double-sided intermittent fillet welding, and staggered fillet welding. From the analysis, it was clear that a buckling-type deformation is generated when the heat input is large. Regarding the welding method, the largest deformation was observed in double-sided continuous fillet welding. In addition, to show the applicability of the developed method to large-scale problems, the developed method was applied to the analysis of the car deck of a pure car carrier ship. As a result, it was found that the developed method can analyze the welding deformation of a large-scale stiffened thin-plate model in practical computing time.

Roll-Coupling Effect on Ship Maneuverability

Roll-coupling effect on ship maneuvering motions is not negligible for high speed vessels, large container ships, passenger ships etc. To perceive the roll-coupling effect on the ship maneuverability, this paper proposes new simplified formulae for course stability criterion and steady turning index in the framework of the linear motion theory. Then, an approximation is employed where the depth wise acting point of lateral force related to roll moment is constant in any oblique motion mode. The course stability criterion including the roll-coupling effect is written aswhere C′ denotes the usual course stability criterion, and the linear hydrodynamic derivatives and l′ the depth wise acting point of the lateral force. The formula is simple and useful for checking the course stability taking the roll-coupling effect into account. To obtain the hydrodynamic derivatives, oblique towing test and circular motion test with various heel angles were conducted for models of a container ship, a pure car carrier and a ferry. In general, course stability deteriorates with increasing Froude number Fn or decreasing of metacentric height GM′, whereas turning performance improves and the time until response reaches steady turning state increases.

Ship Scheduling by Pure Car Carriers with Time Windows and Split Loads in Changeable Speeds

Ship Scheduling by Pure Car Carriers with Time Windows and Split Loads in Changeable Speeds

Numerical prediction and mitigation of out-of-plane welding distortion in ship panel structure by elastic FE analysis

As an application to predict and mitigate the out-of-plane welding distortion by elastic FE analysis based on the inherent deformation theory, a panel structure of a pure car carrier ship is considered. The inherent deformations of different types of welded joints included in this ship panel structure are evaluated beforehand using thermal elastic plastic FE analysis. Applying idealized boundary condition to focus on the local deformation, elastic FE analysis shows that the considered ship panel structure will buckle near the edge and only bending distortion is dominant in the internal region. In order to mitigate out-of-plane welding distortion such as buckling and bending, straightening using line heating is employed. In the internal region, only inherent bending with the same magnitude as welding induced inherent bending is applied on the opposite side of welded joints (fast moving torch). On the other hand, only in-plane inherent strain produced by line heating is introduced to the edge region to correct buckling distortion (slow moving torch). The magnitude of out-of-plane welding distortion in this ship panel structure can be minimized to an accepted level.

横傾斜状態で航行する船の流体力微係数と操縦性

Oblique towing test and circular motion test with changing heel angle were carried out to capture the hydrodynamic forces acting on ship models of container ship, pure car carrier and ferry. Based on the measured forces, the hydrodynamic derivatives with respect to lateral velocity (υ), yaw rate (γ) and heel angle (φ) were obtained for surge force, lateral force, yawing moment and roll moment. Using the derivatives obtained, ship maneuverability traveling in heeled condition was discussed based on a linear theory presented in this paper. As a result, the authors made clear the maneuvering characteristics of heeled ships. When the ship travels in heeled condition to starboard side, she turns to port side. Such characteristic depends on the order of magnitude and the plus (minus) sign of the hydrodynamic derivatives with respect to heel angle, Y' φ and N' φ. In case of the ferry, the turning strength per unit heel angle was about 1/3 comparing with that per unit rudder angle.There is a trend that the turning performance improves with increasing the heel angle. This is due to the course instability appears with increasing the heel angle. The course stability is deeply related to nonlinear derivatives with respect to heel angle, such as Y' υφφ, Y' γφφ, N' υφφ and N' γφφ.

操船シミュレータによる回頭着岸操船訓練評価の基礎的研究

Ship Maneuvering simulator (SMS) have many benefits for pilot trainees who study maneuvering, such as a reasonable scenario, reduced time for technical acquisition of the trainee, and it was the core of the training for harbor maneuvering by a pilot. In this paper, the authors examined an evaluation of the steerage to swing a large pure car carrier (PCC) in front of the berth. It was said that this steerage was difficult for the good experienced captains. A skillful pilot obtained multi-information and recognized it as a pattern. The skillful pilot steered a large PCC immediately. The authors paid attention by taking advantage of the index that was evaluated of the results of this training, using the concept of Mahalanobis-Taguchi System (MTS). The authors defined the normal-range of the ship to turn and evaluated abnormal steerage in the benchmark of the distance and showed it after practice promptly and confirmed the effectiveness of this index by the data of the practice result from 2008 through 2012. The authors confirmed that the proposed evaluation method is effective and helpful to improve the SMS training.

Course stability and yaw motion of a ship in steady wind

In order to achieve safe navigation, it is important to be able to understand and calculate the effects of an external force on the maneuvering behavior of a ship. This paper analyzes the course stability and yaw motion of a ship traveling under steady wind conditions. A course stability criterion and approximate formulae for the yaw motion in steady wind, including the aero/hydrodynamic force derivatives for the ship, are derived. To confirm the reliability of the criterion and formulae, they were used to investigate a pure car carrier in steady wind. The results of this investigation revealed that course instability appears in the head and following wind directions, mainly under the influence of aerodynamic derivatives with respect to the yaw restoring forces. However, this course instability can be reduced by applying steering control. For winds ranging from head winds to beam winds, yaw oscillation appears when the period is relatively long and the damping is small. The analytical formulae derived here can be used to gain a better understanding of ship maneuvering behavior in steady wind.

自動車専用船の貨物倉における気流計測

Due to concerns over CO_2 emissions, demand for seaborne trade of Compressed Natural Gas Vehicles and Hydrogen Fuel Cell Vehicles has been increasing and carriage by Pure Car Carriers (PCCs) is becoming essential. Thus, the Fire Protection Sub-Committee of the International Maritime Organization started the development of requirements for safe carriage of such vehicles and the authors are engaged in this task. One of the significant risks owned by carriage of such vehicles is accumulation of hydrogen and natural gas, which are lighter than air, under ceiling in case of leakage. Though the accumulation of gases depends on air flow, air flow in cargo spaces in PCCs has not been evaluated. The purpose of the research is to provide a basis for the research on the prevention of accumulation of gases by grasping actual air flow in such cargo spaces. We measured air flow on PCCs occupied by vehicles while berthing under some typical ventilation conditions during voyage, and almost calm positions were observed depending on ventilation condition.