RoPax Ferry Research Articles

Computational analysis of air bubble-induced frictional drag reduction on ship hulls

About 60% of marine vessels’ power is consumed to overcome friction resistance between the hull and water. Air lubrication can effectively reduce this resistance and lower fuel consumption, and consequently emissions. This study aims to analyze the use of a gas-injected liquid lubrication system (GILLS) to reduce friction resistance in a real-world scenario. A 3D computational fluid dynamics model is adopted to analyse how a full-scale ship (the Sea Transport Solutions Designed Catamaran ROPAX ferry) with a length of 44.9 m and a width of 16.5 m is affected by its speed and draught. The computational model is based on a volume of fluid model using the k-ꞷ shear stress transport turbulence model. Results show that at a 1.5 m draught and 20 knots cruising speed, injecting 0.05 kg/s of compressed air into each GILLS unit reduces friction resistance by 10.45%. A hybrid model of natural air suction and force-compressed air shows a friction resistance reduction of 10.41%, which is a promising solution with less required external power. The proposed technique offers improved fuel efficiency and can help to meet environmental regulations without engine modifications.

How do variations in ship operation impact the techno-economic feasibility and environmental performance of fossil-free fuels? A life cycle study

Identifying an obvious non-fossil fuel solution for all ship types for meeting the greenhouse gas reduction target in shipping is challenging. This paper evaluates the technical viability, environmental impacts, and economic feasibility of different energy carriers for three case vessels of different ship types: a RoPax ferry, a tanker, and a service vessel. The energy carriers examined include battery-electric and three electro-fuels (hydrogen, methanol, and ammonia) which are used in combination with engines and fuel cells. Three methods are used: preliminary ship design feasibility, life cycle assessment, and life cycle costing. The results showed that battery-electric and compressed hydrogen options are not viable for some ships due to insufficient available onboard space for energy storage needed for the vessel's operational range. The global warming reduction potential is shown to depend on the ship type. This reduction potential of assessed options changes also with changes in the carbon intensity of the electricity mix. Life cycle costing results shows that the use of ammonia and methanol in engines has the lowest life cycle cost for all studied case vessels. However, the higher energy conversion losses of these systems make them more vulnerable to fluctuations in the price of electricity. Also, these options have higher environmental impacts on categories like human toxicity, resource use (minerals and metals), and water use. Fuel cells and batteries are not as cost-competitive for the case vessels because of their higher upfront costs and shorter lifetimes. However, these alternatives are less expensive than alternatives with internal combustion engines in the case of higher utilization rates and fuel costs.

Design of an electrical energy storage system for hybrid diesel electric ship propulsion aimed at load levelling in irregular wave conditions

This paper focuses on the design stage of an electrical energy storage system which is intended to be used to level the power required by ships for propulsion when sailing in irregular seas. Particularly, a preliminary analysis has been carried out aimed at choosing, between two storage technologies namely battery and ultracapacitor, the more adequate storage system for the levelling action with respect to the period of the sea waves. A sizing procedure based upon a Hilbert transform decomposition of load demand is used. More specifically, a specified threshold frequency has been identified such that, power fluctuations related to irregular seas which are characterized by frequencies higher than the specified threshold, indicate the ultracapacitor as the more appropriate device for load levelling. For sizing the storage device, the load demand has been decomposed into two signals without overlapping frequencies. An optimal control strategy is proposed, by exploiting the decomposition of the load power, which allows simulating ultracapacitor real-time operation within the previously determined size constraints. Numerical results have been carried out referring to a Ro-Pax ferry powered by an electrical motor.

Evacuation of Vessels in Dockyards: A Model Validation Study

Evacuation modelling is continuously open to new scenarios and applications. This study examines the possibility to simulate and predict the evacuation of workers aboard vessels in dockyards. First, we provide new data for a better understanding and quantification of workers’ evacuation performance. Second, we use an existing model (STEPS) and apply a validation protocol from the observed evacuation of 150 workers during an unannounced evacuation drill of a Ro-Pax ferry during the repair period in a dry dock. Despite the uncertainty of initial conditions to configure the scenario, the model accurately represents the observed evacuation (e.g. functional analysis ERD = 0.08; EPC = 1; SC = 0.89) suggesting that current agent-based evacuation models, with appropriate inputs and small adaptations, could be applied to these new challenging scenarios. Overall, this study provides evidence for this new application opportunity to model developers, model users and the research community and promotes the use of evacuation modelling for assessing fire safety in shipyards.

Methane Emissions from a State-of-the-Art LNG-Powered Vessel

To meet stringent fuel sulfur limits, together with NOx limits, ships are increasingly utilizing dual-fuel (DF) engines operating with liquified natural gas (LNG) as the primary fuel. Compared to diesel, LNG combustion produces less CO2, which is needed in targeting the reduction of the shipping impact on the climate; however, this could be significantly interfered with by the methane emission formation. In this study, the methane emissions, together with other emission components, were studied by measurements onboard a state-of-the-art RoPax ferry equipped with two different development-stage engines. The results from the current standard state-of-the-art DF engine showed methane levels that were, in general, lower than what has been reported earlier from onboard studies with similar sized DF engines. Meanwhile, the methane emission from the DF engine piloting the new combustion concept was even lower, 50–70% less than that of the standard DF engine setup. Although the CO2 was found to slightly increase with the new combustion concept, the CO2 equivalent (including both methane and CO2) was smaller than that from the standard DF engine, indicating that the recent development in engine technology is less harmful for the climate. Additionally, lower NOx and formaldehyde levels were recorded from the new combustion concept engine, while an increase in particle emissions compared to the standard DF engine setup was observed. These need to be considered when evaluating the overall impacts on the climate and health effects.

Retrofitting WASP to a RoPax Vessel—Design, Performance and Uncertainties

Wind-assisted propulsion (WASP) is one of the most promising ship propulsion alternatives that radically reduce greenhouse gas emissions and are available today. Using the example of a RoPax ferry, this study presents the performance potential of WASP systems under realistic weather conditions. Different design alternatives and system layouts are discussed. Further, uncertainties in the performance prediction of WASP systems are analyzed. Included in the analysis are the sail forces as well as the aero- and hydrodynamic interaction effects, i.e., the sail–sail and sail–deck interaction as well as the drift and yaw of the ship. As a result, this study provides guidelines on the most important parameters when designing and modeling a WASP ship. Finally, the study presents an analysis of the expected accuracy of the employed empirical/analytical performance prediction model ShipCLEAN.

Comparison of FLACS and BASiL Model for Ro-Pax Ferry LNG Bunkering Leak Analysis

Performing liquefied natural gas (LNG) bunkering involves the risk of accidental leakage. When released from containment, LNG rapidly vaporizes into flammable natural gas and could lead to flash fire and explosion. Hence, LNG bunkering needs to take place in an area without an ignition source called a safety zone. This study compares the safety zone estimated by the Bunkering Area Safety Information for LNG (BASiL) model with that of the computational fluid dynamic (CFD) software FLACS, for Ro-Pax ferry bunkering. Horizontal leaks covering different wind speeds in eight wind directions were compared between the two models. Additionally, a grid refinement study was performed systematically to quantify the discretization error uncertainty in the CFD. Of 24 leak cases, FLACS and the BASiL model results agreed on 18 cases. In three cases validation was inconclusive due to the CFD error uncertainty. The BASiL model underestimated the safety zone distance in three cases compared with FLACS. Future work would be to perform a higher grid refinement study to confirm inconclusive comparison and examine ways to reduce gas dispersion spread for the worst result.

Ropax Short-Sea Shipping and Covid-19 Pandemic: Case of Finland

Traveling was constantly growing among European Union (EU) countries before Covid-19 pandemic. In many coastal regions, passenger and freight transportation were tied together with roll-on/roll-off passenger (ropax) ferries. However, since the pandemic started, the passenger side of ropax operations has been under numerous new restrictions, bans and requirements. These have changed rather much during the pandemic era in Finland, creating more distortion and profound volume loss. In 2020, governmental support mechanisms were implemented to avoid significant losses. Thus, freight transportation has sustained. In addition, some restructuring and changes of ropax ferry routes have taken place. Now ropax companies concentrate on shorter routes, and volumes are more devoted to certain seaports. However, the situation did not improve in 2021, and subsidies continued, revenues were barely growing, and profitability was limited. Regression models suggest that Covid-19 resulted in a loss of 14.9 mill. passengers and 1.178 bill. EUR as revenue, where unitized freight volumes were unaffected.

Recovery of ro-pax ferry traffic from covid-19 under tightening environmental regulations: case Helsinki-Tallinn

In 2020, the number of passengers on international ro-pax ferries collapsed due to the pandemic caused by the Covid-19 virus and subsequent travel restrictions. At the same time, both the International Maritime Organisation and the European Union are setting stringent regulations on carbon dioxide emissions from ships. In this research, we look at what options companies offering ro-pax services have to recover from the Covid-19 pandemic under-tightening environmental regulations and the future options for the industry. The case under study is ro-pax ferry traffic between Helsinki and Tallinn. It is one of the busiest international passenger ferry connections in the world. The economics of transport are based on large high-speed vessels, the combination of passengers and cargo, and sales onboard. We created four scenarios for the traffic: to continue the same high-speed ro-pax system as in 2019, to reduce the number of vessels, to switch to new types of ships, to slow down the speed of the vessels or to divide traffic into faster and slower ships. The research contributes to discussion of competitive strengths of ro-pax transport.

Structural Analysis of Hybrid Ro-Pax Ferry

With the aim of improving the environmental sustainability in the field of maritime transport and with special reference to multimodality and 'green' solutions for coastal transport, within the METRO project (Maritime Environment-friendly TRanspOrt systems), funded under the Interreg VA CBC Programme Italy-Croatia, a project of a hybrid Ro-Pax medium range ferry for coastal navigation in the Adriatic area is developed. The paper presents a part of the conceptual design for the assessment of the global hull structure strength, which is not common for this phase of the project, and that is the structural analysis of the complete ship. For this purpose, a detailed computer model of the geometry of the whole ship was made, which includes all primary and basic secondary structural elements, with the aim that such a model can serve later as a good basis for classification and workshop documentation production during contract phase. Additionally, a preliminary calculation of the scantlings of the complete ship was performed according to BV rules and regulations using the MARS2000 software package, with regard to bending and buckling. Loads were modeled according to real conditions for two unfavorable loading conditions, and static linear analysis was performed using the LS-DYNA software package. The global analysis of bending strength in still water could reveal problematic areas in the structure.

PASSENGER RESPONSE TIME DATA-SETS FOR LARGE PASSENGER FERRIES AND CRUISE SHIPS DERIVED FROM SEA TRIALS


 
 
 This paper describes research that was carried-out under the EU FP7 research project SAFEGUARD and presents passenger response time data generated from five full-scale semi-unannounced assembly trials at sea. The data-sets were generated from three different types of passenger ships, a RO-PAX ferry without cabins (RP1), a cruise ship (CS) and a RO-PAX ferry with cabins (RP2). In total, response times from 2366 people were collected making it the largest response time data-set ever collected – on land or sea. The analysis methodology used to extract the response time data and the resultant response time distributions (RTD) is presented. A number of key findings from the data analysis are presented along with three recommendations to modify the IMO guidelines governing ship evacuation analysis, namely; (a) it is inappropriate to use the same RTD for cruise ships and RO-PAX vessels; (b) a new Day Case RTD is suggested for RO-PAX vessels and (c) new Day and Night RTDs are suggested for cruise ships.
 
 

Analiza radne učinkovitosti predloženih porivnih sustava za odabrani veliki RoPax brod

This paper presents the characteristics of ferry shipping with particular emphasis on large RoPax vessels operating in the Baltic Sea. A critical review of main propulsion system used on large RoPax ferries has been done. Optimal propeller parameters and required brake power have been estimated on the basis of total resistance of bare hull and appendages approximated according to Holtrop-Mennen method. Main engines and generating sets have been selected for minimized fuel consumption approximated with quadratic regression. Operational parameters and costs of analysed large RoPax main propulsion systems have been compared.

Feasibility analysis of an innovative naval on-board power-train system with hydrogen- based PEMFC technology

The maritime transportation sector is one of the main contributors to global emissions of greenhouse gases (GHGs), volatile organic compounds (VOCs), particulate matter (PM), hazardous air pollutants, NOX and SOX. In particular, it is estimated that the CO2 emissions in this sector are about 1 Gt every year. The International Maritime Organization (IMO) adopted stringent emission limits in its Tier III regulation, most notably on NOX and SOX emissions and pledged to reach a reduction in greenhouse gas (GHG) emissions from international shipments by at least 50% by the year 2050, compared to 2008 emissions. For emission control areas (ECAs) these requirements are particularly strict and will be difficult to meet with traditional diesel engines and bunker fuels. Therefore, ship owners need to adopt solutions to bring emissions within these and other future limits by means of environmentally friendly fuels and high efficiency propulsion technologies. In this context, hydrogen and fuel cells play a crucial role, thanks to their low criteria pollutant and GHG emission. This paper presents a techno-economic feasibility study for replacing the conventional diesel engine powertrain, usually employed in Ro-Pax ferries, with an innovative system based on polymer electrolyte membrane fuel cell (PEMFC) technology. The ferry is actually powered by four diesel engines, which deliver a total output of 37.8 MW. The ferry also has two auxiliary engines which give an output of 4.0 MW and also two 2.0 MW bow thrusters for its manoeuvring. The energy analysis has allowed to define the hydrogen consumption for each cruise, as well as the optimal size of the innovative propulsion system. In particular, The PEMFC powertrain is sized at the same maximum power output as the main diesel engine and, thanks to the modular architecture of fuel cells and their flexible performance at partial load, the auxiliary engines are not contemplated. Moreover, in order to identify the best solution in terms of ship’s weight and space requirements, two hydrogen storage solutions based on compressed hydrogen technology and liquefied hydrogen technology, have been analyzed and compared. The economic assessment has been carried out by estimating the CAPEX and OPEX for each H2 storage technology by considering short-term, mid-term and long-term scenarios (from 2020 to 2050).

The quality assessment of ro-pax ferries services: research techniques and procedures

The rapid increase in worldwide trade and mobility influence the need to provide high-quality transport services and adapt them to demands and requirements of consumers. This issue is also observed...

The quality assessment of ro-pax ferries services: research techniques and procedures

The quality assessment of ro-pax ferries services: research techniques and procedures

Blockchain for LBG Maritime Energy Contracting and Value Chain Management: A Green Shipping Business Model for Seaports

Abstract To reduce emissions in the maritime transport sector, the International Maritime Organisation (IMO) follows a global clean shipping strategy. Among the different directives of IMO, currently especially the sulphur emission regulations pose challenges for the shipping industry. Related to this are the established Sulphur Emission Control Areas (SECAs) and the introduced global sulphur cap. To comply with the sulphur restrictions, according to the present technological state of the art, ship-owners have three options for their existing fleet: the installation of emission abatement technologies, the switch to low sulphur fuels, or retrofitting for the usage of alternative fuels. Regardless which option is favoured, most often selected solutions still depend on fossil fuels. The reasons for this can be traced back to the fact that supply of biofuels is not ensured in ports and generally seen as no profitable solution. This paper develops and examines an innovative business model with a special focus on liquefied biogas (LBG). The study bases on collected qualitative and quantitative data, which was used by applying the Business Model Canvas. The results will highlight that the business model bears the potential to promote LBG supply. Next to this, the research will show that blockchain and smart contracts are able to foster the implementation of the business model and optimisation of value chain operations. Lastly, economic advantages were highlighted within a case study that refers to the seaport Karlskrona in Sweden and the RoPax ferries from Stena Line that travel back and forth to Gdynia seaport in Poland.

Ship resistance analysis using CFD simulations in Flow-3D

While designing the power requirements of a ship, the most important factor to be considered is the ship resistance, or the sea drag forces acting on the ship. It is important to have an estimate of the ship resistance while designing the propulsion system since the power required to overcome the sea drag forces contribute to ‘losses’ in the propulsion system. There are three main methods to calculate ship resistance: Statistical methods like the Holtrop-Mennen (HM) method, numerical analysis or CFD (Computational Fluid Dynamics) simulations, and model testing, i.e. scaled model tests in towing tanks. At the start of the design stage, when only basic ship parameters are available, only statistical models like the HM method can be used. Numerical analysis/ CFD simulations and model tests can be performed only when the complete 3D design of the ship is completed. The present paper aims at predicting the calm water ship resistance using CFD simulations, using the Flow-3D software package. A case study of a roll-on/roll-off passenger (RoPax) ferry was investigated. Ship resistance was calculated at various ship speeds. Since the mesh affects the results in any CFD simulation, multiple meshes were used to check the mesh sensitivity. The results from the simulations were compared with the estimate from the HM method. The results from simulations agreed well with the HM method for low ship speeds. The difference in the results was considerably high compared to the HM method for higher ship speeds. The capability of Flow-3D to perform ship resistance analysis was demonstrated.

The Impact of the Underwater Hull Anti-Fouling Silicone Coating on a Ferry’s Fuel Consumption

There are well-known specifics of ro-pax ferry shipping, such as the time factor as a consequence of keeping a regular timetable and the priority given to minimizing heeling, pitching, and rolling caused by maximum focus on passenger comfort and ro-ro cargo safety. It is also extremely important to control the ferry’s fuel consumption, being one of the most important cost components. The aim of the article is to draw the attention of shipping company managers to the great potential that lies in the use of routine operational data, collected exclusively on board the ferries. It is worth noting that the research in this paper is based on standard office software packages rather than advanced statistical methods of data analysis, which are usually not accessible for shipping managers. Contrary to typical ocean-going vessels, there are a number of factors that need to be taken into consideration when analyzing ro-pax ferry fuel consumption. Moreover, these factors occur, in many cases, accidentally and, thus, they are difficult to observe on board the ferry without utilizing expensive and time-consuming methods. The possibility of fuel control is important not only for economic reasons but also due to air pollution caused by engine exhausts. The article presents an estimation of increased fuel consumption caused by the degradation of the hull silicone anti-fouling coating. The presented estimations of fuel consumption may be treated as the base for calculations of the economic effectiveness of ferries. The attempt to resolve the above-mentioned problem was made on the basis of research on a real ferry, which took place on the Świnoujście-Trelleborg line between 2007 and 2019.

ASSESSMENT OF THE MINIMUM SPEED REQUIREMENT IN SAFE RETURN TO PORT

The present paper discusses the aspects of how to assess the compliance of cruise ships and RoPax ferries with the requirement for Safe Return to Port as detailed in SOLAS Ch. II-2/21.4.1 – Propulsion. Part of this requirement is the necessity to be able to maintain a minimum sustained speed of 6 knots in Bft 8 weather conditions, for the worst single compartment damage case. This worst damage case is typically failure of one shaft line or engine room. The present paper discusses these methodologies applied to a 120m expedition cruise vessel. In addition, it presents the sensitivity of this requirement to exact environmental conditions, to the choice of blocked or water-milling propeller and to the ship design speed in calm water. In particular, it is demonstrated that for relatively small and slow passenger ships, the SOLAS requirement may necessitate to increase the intended onboard power.

Installation of Air Lubrication System for Ro-Pax Ferry and Verification of its Effect in Actual Seas Based on Onboard Measurement Data

The authors verified an energy saving effect of an air lubrication system for the domestic service ferry which was one of slender body ships. The energy saving effect was evaluated by the engine output reduction rate of system ON and OFF at speed-trial test. As the result, a net energy saving effect of about 3.7% was confirmed.