The continued growth of global sea trade, with 90% of it being carried by ships, is driving an urgent need for innovative port infrastructure. As trade volumes increase, many of the world’s major ports face significant challenges, from congestion to limited expansion opportunities. As one of important application of large floating structures, Ultra Large Container Vessels (ULCVs), driven by economies of scale, are emerging as a critical solution for trans-ocean shipping. However, only a few ports worldwide can accommodate these massive vessels due to limitations in water depth, emphasizing the need for alternative infrastructure solutions.The engineering challenges associated with ULCVs are multifaceted and include the need for specialized infrastructure that can handle the immense size and draft of these vessels, as well as efficient cargo transfer systems that bridge the gap between ocean- going vessels and regional feeder ships. Additionally, there is a strong environmental focus on mitigating the impact of ballast water, greywater, and blackwater, including treatment systems for invasive species. Floating terminals offer a unique approach to overcoming these challenges, providing sustainable, long-term infrastructure solutions. This article explores the engineering, environmental, and logistical considerations of LFTSTs, highlighting their potential to alleviate port congestion and enhance cargo distribution efficiency. Key design elements, such as advanced mooring systems, automated cargo handling technologies, and innovative energy solutions like Small Modular Reactors (SMRs), are discussed in detail. Additionally, the article examines the regulatory and policy frameworks necessary for the successful deployment of LFTSTs, as well as the challenges associated with their implementation. By integrating cutting-edge technologies and sustainable practices, LFTSTs represent a transformative approach to modernizing global shipping logistics, with the potential to significantly reduce carbon emissions and operational costs. However, critical issues such as high capital investment, regulatory hurdles, and public acceptance must be addressed to realize their full potential.

The structural weight of a shell-plated structure can be reduced in numerous ways. The current investigation presents an example of innovative lightweight design of the pontoon of an offshore platform by utilisation of corrugated structure. Corrugated shell plating is compared with a conventional stiffened panel with respect to strength, weight and cost. For this purpose, an optimisation methodology is developed for shell-plated marine structures. The procedure enables the analysis/comparison of various (structural) solutions with regard to strength characteristics, weight and cost. Here, strength characteristics include ultimate tensile strength, buckling stability and fatigue life analyses. Linear elastic finite-element analyses are carried out to generate input to the structural characteristics studies, which involve several design criteria according to classification rules. The results show that in competition with the traditional stiffened panel, corrugated shell-plated structure can be used as the more lightweight design solution. It can be manufactured and installed at a lower cost. Finally, the structural strength characteristics analyses show that, when designed properly, ABS and DNV classification rules are fulfilled without compromising with the safety margins.

The structural weight of a shell-plated structure can be reduced in numerous ways. The current investigation presents an example of innovative lightweight design of the pontoon of an offshore platform by utilization of corrugated structure. The corrugated shell plating is compared with a conventional stiffened panel with respect to strength, weight and cost. For this purpose, an optimization methodology is developed for shell-plated marine structures. The procedure enables the analysis/comparison of various (structural) solutions with regard to strength characteristics, weight and cost. Here, strength characteristics include ultimate tensile strength, buckling stability and fatigue life analyses. Linear elastic finite element analyses are carried out to generate input to the structural characteristics studies, which involve several design criteria according to classification rules. The results show that in competition with the traditional stiffened panel, the corrugated shell-plated structure can be used as the more lightweight design solution. It can be manufactured and installed at a lower cost. Finally, the structural strength characteristics analyses show that, when designed properly, classification rules are fulfilled without compromising with the safety margins.

The finite element (FE) method is suitable as a numerical tool in the numerical analysis of, for example, ship collision scenarios. It is feasible to simulate and compare different collision scenarios by parameter variations. The objective with this investigation was to establish a reliable and robust FIE modeling procedure for ship-ship collision simulations, using the commercial FE software Abacus/Explicit, by means of parameter sensitivity and experimental analyses. Four types of experiments are presented that have supported the development of the FIE models and simulations with sufficient information for representation of material characteristics and for validation of models: (i) uniaxial tensile tests, (ii) friction tests, (iii) bulb impact with a steel-sheet test and, finally (iv) a bull) impact with a side-shell ship structure. The outcome of the parameter study after calibration against test results was two validated FE models: one of the bulb-sheet test and one of the bulb-structure test.

Based on the design ice load that corresponds to a certain return period, a practical approach for designing the frames behind the side-shell or the bow of a ship subject to ice loading is proposed. Four typical types of section profiles have been selected for modelling and numerical analysis. Non-linear finite element analyses that involve both the geometric and material non-linearity were performed. From the analyses, the relationships between the loads and the beam's cross-section properties were obtained for different permanent set requirements. These relationships were then used for finding the section modulus from which the cross-section of the beam can be decided. Finally, a design example is presented for illustration.

The ship research project DESSO (Design for Survival Onboard) aims at improving the safety of RO/RO (roll-on/roll-off) ferries. The project was organized in the autumn of 2003 in order to use the research and development resources existing in Sweden, combined with international expertise, for a radical RO/RO concept with a focus on safety. One part in the early stages of this project was to identify chain breakers from previous accidents, that is, something that would have prevented, stopped, or reduced the conse-quences of the incident event, in order to obtain a realistic basis of "working on the right problem." A systematic and in-depth analysis of a few selected significant and well-documented disasters was made using the event-chain method. The identified chain breakers were further categorized and analyzed to find ideas and concepts that would prevent these events from occurring. These efforts were further developed into a method where the graphics of event chains with chain breakers are used in workshops with experts in two stages. In general, it was found that "Management" in most cases was the initial cause of the events. Often, "Management" was also the reason for the continuing or worsening of the events. As such, education/training and stricter routines were found to be the most effective methods for reducing accidents and are at the same time an inexpensive measure to take. This, together with online stability calculations and decision-support systems, would have prevented most of the accidents analyzed in this work.

Bow-door systems are designed according to the class rules, of which the IACS UR S8 rules serve as a base. Even though bow-door arms, with the purpose of carrying the bow-doors in an open position, are subjected to some dynamic loads, they are dimensioned according to static loads. On one ferry, a large crack arose in one of the bow-door arms. If the arm had cracked off completely, the bow-door would probably have been lost at sea, as the arm was part of the locking arrangement. This analysis has been carried out in order to analyse whether arms, dimensioned according to a static load, should be allowed to be a part of the locking arrangements of bow-doors. The analysis was carried out with field measurements, in the form of strain and acceleration measurements on an arm during the different load cases it is subjected to. The measured results were applied on a finite element model of the arm in order to find the stress and stress ranges everywhere in the arm during the different load cases. With this information, areas subjected to large stress ranges were identified for which fatigue calculations were carried out. None of the load cases proved to give rise to any serious fatigue, except for the bow propellers, which, in certain situations, excite the arms into resonance cycling. The resonance gives rise to a great number of stress cycles with amplitudes large enough to cause fatigue failure.

An alternative design for the superstructure of a Stena ferry is studied. The existing superstructure is made of aluminium, the alternative is based on composite materials. Optimization of the scantlings for a given basic structural design leads to considerable potential weight savings, provided that fire resistant composites are used.

Bow doors are one of the most vulnerable parts on a RoRo vessel. At the same time, they are necessary for the profitability of today's RoRo vessels. The minimum design rules for bow-door systems, stated in the International Association of Classification Societies (IACS) UR S8, constitute the basis for the class rules. In this work, the Rules of IACS UR S8 have been assessed regarding the structural integrity for bow doors of the ‘clam door’ type. The work is based on previous damage, compared to the design rules, so as to find weaknesses in the rules. Damage was mapped and weak points in the rules as well as in the design and construction stages were identified. For the problem areas found, part analyses were performed. Fractures and cracks dominate as being the cause of damage to bow-door systems. In most of these cases, cracks in welds are involved. Fatigue appears to be a major cause for the development of fractures and cracks. Assuming the bow door as being a rigid body and distributing the forces equally on each support, as prescribed by IACS UR S8, appears to be an approach that leads to inadequate results. The deformation of the door causes the loads on the supports to differ significantly and the real pressure distribution subjects the lower supports to much higher loads then the upper ones. It is common with gaps between the supports in the doors and the corresponding ones in the hull. These gaps considerably affect the load distribution on the supports.

The introduction of environmental aspects in ship design requires a holistic view of the design process. The designer needs to integrate environmental knowledge with the design process without increasing calendar time for the design work. A design tool that supports trade-off analyses with environmental objectives will be presented in this paper. Interviews with experienced ship designers have been conducted to support the mapping of the ship design process. This has resulted in identification of decision points, where environmental aspects could be addressed, and has shown the possibilities of the aforementioned integration. The aim has been to show a design tool that is able to manage geographical differences in sensitivity, when it comes to environmental effects from a ship. The paper will point out changes in approach to include this tool in the design process. This paper demonstrates so-called scoring functions in-a trade-situation with environmental information. The tool produced keeps a lot of information ready at an early stage in the design process and deals with the issue of changing environmental sensitivity in the ship surroundings. Recommendations are given on further development for the use of environmentally focused scoring functions in ship design.

The shipping industry is rapidly changing, putting new demands on ship designers and naval architects. The change is threefold; the configuration of the logistic chains increases in complexity, the structure of the regulatory system involves more aspects, and the employment of new computer-based design tools allows evaluation of different concepts and concurrent design processes. The traditional model of the ship design process does not support multiple concept generation and parallel activities. Design methods based on a systems approach considering the wider system, i.e. logistics and socio-economic system, better respond to the new demands. This paper analyses, through a case study, how Systems Engineering based methodology taught to Naval Architect students influences the design methods they use. The results show that it is important to integrate Systems Engineering training in the ship design education to give the next generation of ship designers the framework they need to handle the changed industry demands and to increase the competitiveness of future shipping services.

For roll-on/roll-off (RO/RO) ships, when transporting more cars within the same deck area on board, it is necessary to adjust or take away the current lashing system. Furthermore, this operation may also decrease the cost and time of operation as well as cargo damages due to lashing. This requirement, combined with the safety consideration on cargo shifting, may lead to concepts of lashing-free deck design. One of the lashing-free concepts suggests that in some conditions cars can be secured without using lashings, mainly depending on the friction between the tire and the deck without lashings. By doing a series of parametric studies of vehicle securing without lashings under roll and pitch motions, it was found that the value of the maximum required friction coefficient between the tires and the deck is highly relevant to the roll and pitch amplitude, pitch period, orientation of vehicles on decks, and the vertical location of vehicles from the baseline of the vessel.

Due to their characteristics and lower maintenance cost, lightweight aluminum structures have been widely used for manufacturing deck structures. When this type of structure is developed, the natural frequencies for the unloaded deck may increase, while the natural frequencies for loaded decks are most likely to decrease and new problems of vibration and damping may appear. In addition, it has already been shown by the authors that compared to the load effects of normal cargo, the dynamic structural behavior of a vehicle-loaded deck is different due to the participation of vehicle vibrations. The current paper presents a modal analysis by both testing and finite element (FE) calculation for a lightweight deck using aluminum panels. By comparing the results between the unloaded and car-loaded cases, it is shown how vehicle loading influences the dynamic structural behavior of the deck structures. The authors report that an aluminum panel mechanically connected to a steel frame may participate in some mode shapes of vibrations that significantly increase the corresponding damping ratio. The reasonably good agreement between modal testing results and FE calculations validates the finite element model, which may then be used for further dynamic analysis. The authors found that the spring-damping systems of car suspension and tires can interfere in the dynamic transmission of the vehicle mass into the deck structure. The study enables structural engineers interested in the design of car carriers to have a better understanding of how the vehicles parked on decks can influence the dynamic characteristics of the vehicle deck systems.

This paper presents the review and studies at various levels of problems concerning the authors’ previous research on the dynamics of vehicle–deck interactions. The various levels of study include the dynamic structural behavior of vehicle–deck systems, vehicle vibrations, damping effects of vehicles on structural systems, dynamic interactions between tire and deck surface, and vehicle securing on decks during ship motions, etc. The study includes analytical, numerical and experimental analysis. Practical problems encountered by Ro–Ro ship designers are addressed by discussing those analysis. It is shown that influences from the dynamics of vehicle–deck interactions are relevant to a number of aspects of issues, such as the excitation frequency range, how detailed information of the structural system response is required, the structure characteristics, and positions and orientations of vehicles on decks, etc. The study contributes to the knowledge for the naval architect and vehicle engineer on how significant the dynamics of vehicle–deck interactions are when dealing with relevant problems.

The use of light weight materials is increasing at a rapid pace in the present day industry. Automobiles, aircrafts, ships and several other fields are increasingly finding large potential in using lighter materials for construction. In the past few years a number of water borne means of transportation have been moulded from composites. For ships, this leads to reducing the light weight and thus an increase in the capacity of the payload. A reduction in the light weight of the ship implies more cargo and more revenue generation for the ship owner. Over an average lifetime of 25 years, the amount of revenue generated could be significant, due to which a number of ship owners are giving a serious thought to the usage of light weight materials in shipping. Stena Line, a Swedish shipping company has a number of passenger ferries running in the European region. They are also the proud owners of the HSS series of ships, which are unique as they are catamarans made completely in aluminium. Being the pioneers in the shipping industry, they have considered the possibility of having a sandwich superstructure for one of their ferries, HSS 900. This paper looks into the preliminary design of the structure under DNV regulations. While fire safety is also part of the project, this paper focuses on the structure. Different kinds of fibres, resins and cores could be used for making the sandwich construction. The fibre making the faces could be E-glass, S-glass, carbon fibre etc, the resin systems also provide a variety of options like the polyesters, vinyl esters and phenolics. Similarly the core material could be honeycomb, PVC or PU. In this paper, possibilities of using these materials for the making the superstructure has been looked into. A preliminary calculation shows how much in terms of light weight of the vessel could be saved if sandwich construction is used. As it is weight critical approach that is the driving factor in using light weight materials, an optimization of the structure by breaking it up into sandwich panel, spacing of the transverses and longitudinal has also been performed. While optimizing the sandwich panel, four major criteria of maximum normal stress, maximum shear stress, wrinkling stress and maximum allowed deflection have been explored. The limit point where all the four requirements are met and the weight is minimum possible has been considered as the optimum point. All in all it is a sandwich superstructure, which has been optimized for weight.