Ebook: Theory and Practice of Shipbuilding

SORTA 2024 is the 26th Symposium on the Theory and Practice of Shipbuilding, held in memory of Professor Leopold Sorta, and jointly organized by the Maritime Department, University of Zadar, Croatia, and the Faculty of Engineering and Architecture, University of Trieste, Italy, with support of the Digital Innovation HUB Innovamare, Šibenik, Croatia. The significant tradition of the symposium demonstrates the importance of shipbuilding science and practice for both the economic and scientific development of the Republic of Croatia. Continuing this significant tradition, the SORTA 2024 Symposium will contribute to the integration of existing knowledge and experience in the context of modern scientific and professional achievements in the field of shipbuilding, offshore engineering, maritime and inland navigation, through invited lectures, scientific and professional papers, panel discussions and round tables.

The 26th Symposium on the Theory and Practice of Shipbuilding (SORTA 2024) is back in Zadar, where it was last held in 1998, when it was organized by Lamjana Shipyard and Tankerska Plovidba. The Standing Committee was present at the symposium, including representatives of the Croatian maritime excellence. An International Scientific Committee, composed of members from international academic institutions and relevant industrial sectors, further ensured the scientific quality of the symposium under the guidance of the chairperson, Professor Jasna Prpić-Oršić (University of Rijeka).

Previous editions of the symposium were held in Zagreb (1974, 1976, 1978), Opatija (1980), Split (1982), Belgrade (1984), Pula (1986), Zagreb (1988), Dubrovnik (1990), Opatija (1992), Dubrovnik (1994), Zagreb (1996), Zadar (1998), Rijeka (2000), Trogir (2002), Plitvice Lakes (2004), Rijeka (2006), Pula (2008), Lumbarda (2010), Zagreb (2012), Baška (2014), Trogir (2016), Split (2018), Rijeka (2020), and Malinska (2022).

The Editors

The introduction of innovative materials and the ability to ensure a reduced environmental impact is a topic of significant interest among experts in ship- and boatbuilding sectors. Materials must be able to combine physical and mechanical properties adequate to the intended purpose and uses, while also addressing fundamental aspects of sustainability. As a first aspect, they must ensure recyclability at the end of their lifecycle, combined with low energy consumption and limited exploitation of resources during production. Nowadays, these factors represent key parameters for selecting construction materials, in agreement with the Green Shipbuilding approach. In recent years, innovative plastics able to offer these advantages have been increasingly considered as potential structural materials for small vessels. Indeed, they combine chemical resistance, anti-corrosion properties, and high flexibility while ensuring recyclability possibilities. Given the novelty of adopting such materials for boat construction, it is necessary to investigate their mechanical and strength properties through adequate laboratory testing aimed at characterising maritime applications. The present article, after giving a description of the considered plastic materials in terms of structure and properties, aims to detail a proper experimental campaign for mechanical tests addressed at validating their use for structural purposes in boat constructions.

This paper focuses on the concept design of a passenger ship tailored to accommodate the needs of 100 passengers, distinguished by its fully electric propulsion with batteries for electric energy storage and the integration of solar panels. Operates in year-round navigation short-sea services, with a typical operational profile of approximately 3 nautical miles distance followed by 30 minutes of sailing and 30 minutes of charging time, targeting a service speed of 7–8 knots. The benefits of the catamaran passenger ship are given as a sustainable coastal means of sea transportation that incorporates technologies to enhance comfort, operational efficiency, and environmental sustainability. As a result, the developed concept design incorporates an inclusive general arrangement for the required number of passengers. Following that, a hull form was created in terms of the efficiency of the electric propulsion, while the power was obtained by several methods. Evaluation of masses and the definition of the centre of gravity allowed for stability calculations for six scenarios, according to the Croatian Register of Shipping. Lastly, the ship’s operational profile was learned, and the energy balance and battery pack calculations and options were performed with sensitivity analysis for the possible solutions of the range of displacements.

Estimating the steel weight of ships during the early conceptual stages is of the utmost importance since it represents about 50% of the lightship weight of the ship. From a technical standpoint, it significantly affects cargo capacity, design speed, stability, and ship safety, thus requiring an accurate estimation. The steel weight is usually evaluated using simple empirical formulations during the concept design, mainly based on the ship’s main particulars. Those formulas are derived by statistical analysis of past projects and can be applied only for the specific ship type (or types) included in the considered database. In the literature, many formulas are present mainly related to cargo ships. Currently, no empirical formulation is available for cruise ships that are applicable in the very early conceptual stages. The present study aims to identify an empirical formulation for estimating the steel weight of a luxury cruise ship based on calibrating a set of existing empirical formulas.

Each year, approximately 8 million tons of plastic waste enter the oceans, making it one of the most pervasive pollution problems globally. This issue has prompted a global call for preventive measures due to its detrimental impact on marine life, fishery resources, coastal livelihoods, tourism, the environment, and long-term human health. Marine debris is a significant environmental concern, affecting both human health and aesthetics. Ports and their surrounding areas face particularly severe challenges due to high waste accumulation and the difficulty of cleanup operations amidst heavy ship traffic. This paper presents the results from the early stage of design for a Waste Collecting Vessel (WCV), a versatile ship capable of performing multiple functions, including surface garbage removal, waste collection from other ships, oil spill recovery, and weed cutting. Our research offers new insights into the design and operation of eco-friendly small ships, contributing to sustainable maritime environmental management. The culmination of this work is a conceptual proposal for a catamaran equipped with advanced technologies for efficient waste management in ports and coastal areas. The design is envisioned to be zero-emission and autonomous.

The paper discusses and highlights the basic challenges in the structural design of a 70-meter river floating passenger terminal. It is designed as a multi-deck floating object characterized by a large superstructure with a specific shape, equipped with solar and glass panels and the absence of transverse/longitudinal bulkheads. The height of the superstructure is larger compared to the height of the lower hull and its influence on longitudinal strength should be considered in the very early design phase. Croatian Register of Shipping (CRS) Rules for the Classification of Inland Navigation Vessels Part 2 – HULL AND HULL EQUIPMENT, July 2021 were used to define design loads, corrosion deductions, safety factors, etc. The main results and challenges have been briefly presented for the preliminary design phase where global structural response has been evaluated based on the full-ship FE model. Feasibility structural calculation due to yielding and buckling issues has been performed following criteria given in CRS Rules and a feasible design solution has been proposed.

In recent years, there has been a significant increase in interest in ferrocement as a material for various engineering constructions. Due to its ease of shaping complex forms, it has been used previously, for example, in constructing ship hulls or tank walls. Apart from the advantages associated with the ability to shape thin elements, improved mechanical properties compared to concrete, and resistance to chemical actions, ferrocement is becoming an increasingly attractive solution for both economic and ecological reasons. The paper presents the results of preliminary analysis aimed at determining the potential use of ferrocement as a material for constructing floats for houseboats. The assumptions regarding the load-bearing structure are presented, and the dimensioning process is described. Due to the lack of standards for the ferrocement structures, the calculations were based on the guidelines of the European standards for concrete and reinforced concrete structures. Subsequently, the focus was on the problems associated with determining the ferrocement strength parameters, as well as discussing the consequences of applying reinforced concrete theory to its calculations. Also, the areas that required reformulation due to the strictly adopted assumptions related to the concrete behavior and the method of load transfer through reinforced sections have been indicated.

The Moth-class sailboat belongs to the international class of sailboats. It is the fastest single-seater class in the world. A vessel that wants to compete in the Moth class must have a certificate from an International Organization that defines the rules and dimensions of the entire sailboat, which limits design. The equipment of the sailboat includes two hydrofoils – main and stern. Hydrofoils must be defined in accordance with the rules. The paper presents the principle of selection of elements of the main hydrofoil assembly, which includes the foil profile, holder and mechanical angle of incidence regulator. Asymmetric and symmetric foil profiles and hydrofoil holders were considered, which were analyzed with software packages. For the selected foil profile and main hydrofoil holder, the choice of materials, laminate plan and production technology are shown. In conclusion, the advantages and disadvantages of the chosen solutions are commented.

Grillage design is one of the most common tasks in ship structural engineering, as many components of a ship’s secondary structures, such as hatch covers and decks, are grillages. This paper presents the current state of development of D3V-SGD, an open-source software tool for the design and analysis of ship grillage structures developed by students and researchers from UNIZAG FSB. Realized as an extension module to D3V, an open-source 3D Modular Viewer in Python, D3V-SGD currently features a parametric model for hatch covers, a GUI with 3D visualization, and automatic generation of analysis models for determining structural responses. These models include both grillage beam analytical methods and FEM using shell elements. For FEM analysis, the open-source program OOFEM has been utilized, recently adopted for the analysis of ship thin-walled structures.

Trim optimization is a promising strategy to improve the ship resistance characteristics and consequently increase its energy efficiency. Most of the research conducted so far regarding trim optimization is focused on unrestricted water. Since sailing in restricted water alters the flow and pressure distribution along the ship hull it is necessary to analyse the effect of trim on the total resistance in shallow and confined water. In this study, the effect of trim on the total resistance of the KCS model is analysed using computational fluid dynamics. Numerical simulations of resistance tests are performed for an even keel and four trim angles in restricted water. Numerical uncertainty for the total resistance, sinkage, and trim angle is assessed using different grid resolutions and time steps. The obtained numerical results are validated against the experimental data available in the literature. A detailed analysis of the free surface elevation, wave patterns, distribution of hydrodynamic pressure and wall shear stress, and velocity field on the symmetry plane is carried out. It is shown that a reduction of the total resistance in confined water can be achieved by adjusting the trim angle.

The paper presents new results of the full-scale measurements of waves and ship motions for the research vessel BIOS DVA offshore Split in the Adriatic Sea. Experiments were performed by measuring waves simultaneously and ship responses for five different heading angles and two ship speeds of 7 and 3.5 knots. Waves were recorded by a solar-powered floating buoy, while the ship motion was measured with an Inertial Measurement Unit. Time series of waves and ship motion were analyzed using the STATREL software, and a comparison of statistically and spectrally defined characteristics is presented. The new campaign was organized as the comparison of previous measurements with seakeeping calculations concluded that additional experiments were required to improve the accuracy of seakeeping predictions, especially for the mean zero up-crossing period in the following seas. Therefore, special attention is given to the motion in the following waves in addition to analyzing the influence of ship speed on responses.

The prediction of parametric rolling in ships remains a critical area of research due to the significant impact on maritime safety and vessel performance. Among the various parameters influencing parametric rolling, roll damping is notoriously challenging to assess due to its nonlinear nature. Accurate prediction of roll damping is essential for reliable parametric rolling simulations. Traditional methods such as the Ikeda method provide valuable insights but are limited in scope, often tailored to specific instances of wave height and wavelength. Decay tests, while useful for individual cases, lack general applicability across a wide range of conditions. Computational Fluid Dynamics (CFD) offers a more comprehensive approach, enabling the analysis of complex interactions between the vessel and the surrounding fluid. However, CFD simulations are computationally intensive and require significant resources. This paper reviews the current methodologies for assessing roll damping, highlighting their advantages and limitations. It underscores the need for integrated approaches that combine empirical data, analytical methods, and advanced simulations to achieve more accurate and reliable predictions of parametric rolling across diverse maritime conditions.

Design of fixed offshore platforms is performed in accordance with the regulatory guidance as API Recommended Practice 2A-WSD. However, when extending the lifetime of existing platforms beyond their designed lifetime, structural degradation, marine growth and updated knowledge of the recorded environmental conditions at the exact location where the platform was operated must be taken into account. In the present study, the specific requirements are reviewed for fixed gas exploitation platforms operating in the Croatian part of the north Adriatic Sea. The paper firstly provides overview of the present offshore activities and existing platforms in the Croatian part of the Adriatic. Further, following aspects relevant for the lifetime extension framework of fixed platforms are considered: description of the environmental conditions and seismic characteristics in the north Adriatic Sea, expected severity of the corrosion and marine growth in the region and procedures for strength and fatigue assessment. The aim of the paper is to review state-of-the-art analysis models and computational tools and to serve as the guidance for the engineers involved in the design, inspection, maintenance, and lifetime extension of fixed offshore platforms in the Adriatic. Also, research needs for the improvement of the existing inspection practice are identified.

In the competitive shipbuilding industry, gaining a competitive advantage between shipyards is necessary. A competitive and sustainable shipyard process must constantly be monitored to increase productivity, efficiency, and quality. One of the major concerns in modern shipbuilding is achieving efficient ship outfitting, particularly for high value-added ships. Maximizing the level of the ship’s equipment installation before launching is one of the essential goals in modern shipyards while outfitting after the launching tends to be reduced to a minimum. Therefore, this paper will analyze the current situation in the observed shipyard in general, mainly the ship modular outfitting concept, which could improve its characteristics and impact the ship production process. Hence, the modular outfitting approach’s benefits, requirements, and potential drawbacks will be discussed. The module assembly and installation activities will be established as a case study, including all necessary resources for the selected machinery module. A network diagram with a critical path will be provided for analysis while a digital computer 3D modelling and visualization of module assembly and installation is developed. Furthermore, such model authors plan to use in further research as a basis for ship design and production digital integration to support the digital transition of the shipbuilding industry.

Previous research findings regarding mechanized welding were used as a starting point for project Dynalink. Aim was to test process competitiveness, so mechanized process was compared with hand welding. After successful welding completion with Railtrack, process was retried with Submerged Arc Welding carriage TFD1. Improvements were suggested for further research.

After previous successful reverse engineering projects (ship hull, mast deviation, infrastructure scanning), in this paper reverse engineering methods were used to reconstruct ship piping system. Original drawings of those systems were lost and additionally, designated area suffered damage from fire. Pipes were reconstructed from point clouds and connected with shipyard main database.

Air pollution from the shipping industry is an ongoing problem that requires exploring innovative technologies for effective resolution. The integration of wind-assisted ship propulsion (WASP) technology offers a promising route towards decarbonisation of the shipping industry. The paper investigates possible fuel savings and CO₂ reduction by implementing wind assisted propulsion on a case-study vessel operating on a known route in the Adriatic Sea. The long-term contribution of added wind propulsion is analysed by implementing a Velocity Prediction Program (VPP) and available meteorological data for the area of interest. VPP is modified to predict the contribution of wind propulsion to the overall propulsion necessary to achieve the vessel design speed. The case study quantifies long-term fuel savings for ship operating a liner route and harnessing favourable (predictable) north-west winds, complementing the conventional propulsion systems.

Contemporary maritime industry places a significant emphasis on understanding human cognition and decision-making processes since human error is a predominant factor in over 80% of maritime accidents. With a decreasing number of crew members on ships, seafarers experience increased workloads and responsibilities, leading to a higher likelihood of errors. Eye tracking technology is a method used to monitor and record the movements of a person’s eyes in various situations. By using special glasses or cameras, eye tracking technology records eye movement, gaze duration, blink rate and pupil size, which represent a person’s cognitive and emotional state. This paper analyses the different areas where eye-tracking technology can be applicable in maritime navigation, including research on visual attention, gaze patterns, situational awareness, human-machine interfaces, mental workload and training improvement. The data obtained from various studies on eye tracking technology enable the development of preventive measures and corrections of human errors, especially during the seafarer’s training phase and in equipment layout and design. Eye tracking technology represents a valuable tool to enhance safety and efficiency in maritime navigation, as shown in this paper, which provides a foundation for future research and practical implementation.

The development of world trade is based on the global transport of goods and people, and the most advantageous and most common form of transport is transport by ships, which, with their service in a demanding medium such as seas and oceans, must withstand numerous challenges such as corrosion and fouling. The hull and the rest of the structure of modern ships are made mainly of carbon steel and aluminum, which are susceptible to corrosion damage in the marine environment and require adequate protection against corrosion. The most commonly used method for corrosion protection on ships is protection with coatings that form an impermeable barrier between steel or aluminum and marine environment. In addition to the corrosive effects of the sea, the outer surface of the ship’s hull is also exposed to fouling of marine organisms such as bacteria, algae and shellfish. By settling on the ship’s hull, they increase the friction between the hull and seawater, increase the weight of the ship and cause damage to the protective coating. The most commonly used method for protection against fouling are anti-fouling coatings that are applied to the outer surface of the underwater part of the ship’s hull. Antifouling coatings have been in use for many years, but with raising awareness of the protection of the sea and marine organisms and the progress of technology, some old types of antifouling coatings based on tributyltin base have been abandoned and banned, and new, more effective and less harmful coatings for the marine world are coming into use. Currently, the most common antifouling coatings in shipbuilding are self-polishing antivegetative coatings based on copper biocides. In this paper, the efficiency and quality of antifouling coatings with an insoluble matrix and self-polishing coatings on steel and aluminum substrates were studied.

Maritime transportation systems are increasingly embracing advanced technology and relying more on digital solutions, resulting in the escalation of potential cyber threats and the expansion of attack surface. Furthermore, in the upcoming years, the adoption of AI-based navigation and autonomous vessels will further broaden the scope of attack vectors. The widespread use of technologies like Electronic Chart Display and Information System (ECDIS) and Automatic Identification System (AIS) reveals gaps in current cybersecurity protocols within the maritime sector. In this paper, we aim to highlight the consequences of lacking proper security protocols employed for digital systems onboard ships by examining historical cyber-attacks on vessels. Additionally, we will explore the concept of a Maritime Security Operations Center (M-SOC), which can play a major role in enhancing cybersecurity in the maritime sector. The unique nature of M-SOC, which operates on real-time threat detection, can enhance resilience and protect critical infrastructure. Moreover, M-SOC serves as a centralized hub for analyzing cybersecurity data and coordinating response efforts.

This paper presents an analysis of the proliferation of unmanned aerial and maritime vehicles (UAMVs) and their implications for future military operations. Although initially, the development and production of such vehicles were under state control, they recently moved to the private sector, and their capabilities were constantly improved. They are used for civilian and military purposes. Since there has been a drastic drop in the cost of UAMV production, they are becoming available to almost all armed forces, while previously, it was the privilege of only a few countries. The rapid development of UAMV for military purposes is considered as a new technological revolution that is already significantly changing the character and way of conducting armed conflicts, and it is estimated that their participation and importance in future potential disputes will be increased. The development of UAMVs and their use in armed conflicts has led to their proliferation and production race. The paper analyses the experience of UAMV use in recent military conflicts and identifies its advantages and limitations. Finally, it draws conclusions and recommendations for strategic military planners on implementing those technological changes within the armed forces and provides an adequate response to this threat.

On modern ships, particularly small coastal tourist ships around 50 meters in length, ship owners often prefer stainless steel propeller shafts, lubricated by an emulsion of grease and seawater, with no aft sealing. The IACS unified requirement UR M68 prescribes the expression for evaluating shaft diameter based on service loading and tensile strength of the shaft material. However, it should be noted that the formula is only applicable to shafts made of carbon, carbon manganese, and alloyed steels. Stainless steel is excluded. The aim of the paper is to propose the extension of the UR M68 formula for propeller shaft dimensions to cover stainless steel shafts. The chosen dimensions are dependent upon the shaft line concept, especially the type of lubricant, material and predetermined shaft loading (torque or power at the relevant speed). These are currently the only available initial quantities for dimensioning the propeller shaft. Dimensioning propeller shafts, including stainless steel, is a crucial aspect in the development of marine propulsion shafting systems. The presented approach is based upon the fact that the expected failure mechanism of the shaft is fatigue due to cycling loading. Additionally, it highlights and implements the relationship between fatigue strength and the tensile strength of the shaft material.

This paper explores the transformative potential of artificial intelligence (AI) in revolutionizing leisure sailing experiences. Traditionally, leisure activities such as sailing have offered limited opportunities for personalization. However, recent advancements in AI enable dynamic customization of onboard environments based on individuals’ emotions and preferences. Using leisure sailing as a case study, this paper demonstrates how AI can be leveraged to create personalized and engaging experiences. By analyzing real-time data from onboard sensors, AI systems can adjust environmental factors such as lighting, music, ventilation, colours, and furniture layout to optimize comfort and enjoyment. The paper also delves into the technical challenges of implementing AI in leisure sailing, including data collection, real-time processing, and ethical considerations around privacy and consent. It emphasizes the potential for AI to enhance the leisure experience, inspiring further research and development in this area. In conclusion, this paper envisions a future where AI is seamlessly integrated into leisure sailing, creating tailored, immersive experiences that maximize participant comfort and enjoyment.

Optimal ship routing is crucial for enhancing safety, reducing travel time, and minimizing fuel consumption. This paper introduces and examines recent advancements in stochastic optimization techniques, emerging methods and models for weather-aware ship routing. As marine transportation faces increasing challenges due to climate change and extreme weather events, the need for robust and efficient routing strategies has become imperative. A ship route that is subject to uncertainties is considered stochastic. Therefore, a comprehensive overview of emerging stochastic optimization methods that address the inherent uncertainties in weather forecasting and their impact on optimal routing is presented. The paper explores various approaches, including Markov decision processes, stochastic dynamic programming, and scenario-based optimization, highlights their applications in fuel consumption minimization, ensuring safety and improving time reliability. The integration of ensemble weather forecasts and probabilistic models to capture the stochastic nature of oceanic and atmospheric conditions is discussed. Additionally, computational challenges associated with these methods are analyzed along with recent algorithmic improvements that enhance their scalability and real-time applicability. The inclusion of multiple objectives, such as environmental impact and economic factors, within the stochastic framework is also addressed. Finally, a promising research direction is identified and potential synergies with machine learning techniques to further account for an increasingly uncertain marine environment.

This preliminary report will present the latest results of a demonstration level testing of augmented (AR) and mixed reality (MR) devices in shipbuilding processes as a part of the Mari4_YARD project. The main goal of these tests and the project is to develop human-centric solutions which can preserve industry-specific knowledge, enhance the possibilities of presented technologies and improve work tasks’ performance. The tests will also help to define what kind of performance level indicators can be measured in the shipyard’s digital and real environment and can they be achieved.