Early-stage design is the most critical phase in a vessel’s development, as this is when many of the major decisions are made and locked in for the remainder of the design process. Most early-stage design frameworks are tailored to conventional vessels, aiming to explore a broad design space—essentially assessing numerous design variations. However, to evaluate such a wide range of design solutions, these frameworks often sacrifice accuracy in their analysis methods to allow for more design evaluations. Consequently, low-fidelity tools are typically used for early-stage design exploration.
For novel vessel designs, low-fidelity analysis methods are insufficient for accurately assessing performance, as they often fail to capture the new and sometimes complex physics involved. While increasing the fidelity of analysis methods leads to more accurate performance assessment, it also raises computational costs, making it impractical to evaluate a large number of design variations. Multi-fidelity models, which combine lower-fidelity methods with a high-fidelity analysis method, offer a promising solution for enabling higher-fidelity assessments earlier in the design process. Thus, this dissertation builds the architecture of a multi-design architectural framework for early-stage design of novel vessels...@en

Ships play a crucial role in global transportation, yet they significantly contribute to greenhouse gas emissions. The International Maritime Organization targets net-zero emissions by 2050, necessitating cleaner energy solutions. Solid oxide fuel cells (SOFCs) offer higher efficiency than diesel engines, reducing carbon emissions and toxic pollutants. This dissertation explores the integration of SOFC systems into ships, assessing fuel options, efficiency, and operational challenges. Experimental studies examine SOFC performance under ship motions, highlighting the need for design adaptations. Thermodynamic analysis compares various fuels, identifying methane and ammonia as optimal choices based on efficiency and heat demand. A megawatt-scale SOFC system is conceptually designed to enhance power density. Hybrid power plant simulations demonstrate significant emission reductions, especially for auxiliary loads. The study concludes that SOFCs are viable for multiple ship types, particularly those with stable load profiles. Further advancements in alternative fuels and system design are essential for widespread adoption.@en

Submarine power cables (SPCs) are vital for the offshore wind industry, particularly as wind farms expand into deeper and remoter ocean areas rich in wind resources. These environments subject SPCs, especially dynamic power cables (DPCs) connected to floating wind platforms, to repetitive loadings and consequent fatigue failures, posing substantial challenges within the industry.

Predicting the fatigue life of SPCs involves several critical steps, with local mechanical analysis acting as a pivotal bridge that significantly impacts overall fatigue life estimation. This analysis assesses overall cable behaviours, such as stiffness, and detailed component behaviours, such as stress and strain conditions. The accuracy of the local mechanical analysis crucially influences the ultimate fatigue life estimation. Currently, large safety factors are employed in engineering to compensate for uncertainties due to insufficient understanding of local mechanical behaviours. Therefore, there is a need for a modelling method that can accurately estimate the local mechanical behaviour of SPCs.

This PhD project is dedicated to developing an effective modelling method for the local mechanical analysis of SPCs. An extensive literature review on SPC configurations, design processes, and methods for determining mechanical behaviours is presented in Chapter 2. This chapter focuses on prevalent loadings of tension and bending and discusses the complexity of SPC structures, particularly due to their unbonded, multi-layer, helical component nature and associated stick-slip issues. Two approaches—analytical and numerical—are used to capture these behaviours, with numerical methods preferred for their ability to handle complex structures. However, these methods struggle with efficiency when detailed analysis is necessary. The balance between accuracy and efficiency in developing an effective numerical model hinges on resolving three specific issues: constructing appropriate finite element, managing contact issues, and establishing suitable boundary conditions.

Chapter 3 addresses the aforementioned challenges. First, it introduces an element combination—beam plus surface elements—to simulate the helical metals within SPCs, a method previously validated for accuracy and efficiency. This combination undergoes further verification in subsequent chapters. Secondly, the contact issue, particularly the initial residual stress from extruded polymers during manufacturing, is tackled using contact damping to simulate its effects, enhancing model efficiency and convergence. Lastly, the challenge of setting appropriate boundary conditions is addressed through periodic boundary conditions derived from the homogenization method, applied to a repetitive unit cell (RUC) whose length is reduced to increase computational efficiency. The resulting model, referred to as the RUC model, is applied to SPC samples and validated against test data on tension and bending.

The effectiveness of the RUC model under tension is confirmed in Chapter 4 through material tests and a tension test on a DPC sample. The model demonstrates superior performance in terms of accuracy and efficiency compared to traditional full-scale models. Similarly, Chapter 5 validates the RUC model under bending conditions using tests on both three-core DPC and single-core SPCs. The model is verified against traditional full-scale models, affirming its robustness.

Subsequently, Chapter 6 explores the RUC model’s application in analyzing the combined effects of tension and bending on DPCs. The study extends to parametric analysis of internal components and helical pitch lengths, providing crucial insights for cable design.

Finally, Chapter 7 concludes the dissertation by summarizing the key findings and offering recommendations for further research building on the current study. Additionally, it outlines guidelines for employing the proposed model in practical scenarios
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Currently, the energy transition is a topic for discussion and many organizations are taking measures to reduce the effects of climate change. Armed forces are exempt of these new regulations on the grounds of national security, but some have already started taking steps to reduce the amount of harmful emissions. Due to the high efficiency and advantages that fuel cells present, the aim of this master's thesis is to study their feasibility on board of a naval surface vessel, testing it in a concept design.
This report consists of two main parts. The first part tries to find the most suitable combination of naval surface vessel, type of fuel cell, and type of hydrogen carrier. It is concluded that the types of naval surface vessels that could benefit the most from the use of fuel cells are frigates and mine warfare vessels, in order to reduce their acoustic signatures; and offshore patrol vessels (OPVs), due to their constant base load, because it is a type of ship that is mostly cruising or patrolling.
Solid oxide fuel cells (SOFCs) are here considered to be the most promising type of fuel cells for naval surface vessels. This is not only because of their high efficiency, but also due to their ability to internally reform hydrogen carriers, making them more versatile. Other fuels than pure hydrogen can therefore be selected, which leads to the choice of ethanol and methanol as best candidates. The latter has already shown good performance when combined with SOFCs and is largely available worldwide.
Next, in the second part of this report, the concept design of an OPV using SOFCs fuelled by methanol is tested. On a systems level, the integration of SOFCs adds multiple elements and complexity to the power plant of the concept design. Moreover, since the SOFCs are only used to generate the base load needed to reach cruising speed and its auxiliary power, a peak power source is needed to reach higher speeds. After having considered batteries, diesel engines, and methanol engines, it was concluded that methanol engines provide the highest operational flexibility, on top of being the lightest combination.
When comparing the concept design to the reference design, they both score similarly in terms of redundancy and they both fulfil the same design requirements. In terms of operational capabilities, the concept design can sprint for less time due to the difference in efficiency of the power source used to cruise (fuel cells) and to sprint (methanol engines) and does not have the ability to extend its range above the design requirement, opposite to what the reference design can.
The use of a SOFC-based power plant shows a reduction in CO2 emissions between 13-23% depending on the type of mission, a 100% reduction of SOx and PM due to the use of methanol as a fuel, and a reduction of at least 68% in NOx emissions.

This research examines the difference between two major component replacement strategies for the novel floating offshore wind turbines (FOWT), in terms of support vessel CO2eq emission and cost together with FOWT downtime. The first strategy is utilising a crane vessel to replace a component in offshore, this is called the heavy lift maintenance (HLM) strategy. The other strategy is the tow to port maintenance (TTPM) strategy, where the floating offshore wind turbine (FOWT) is towed to port to be serviced. Royal IHC is looking for a reliable and relatively quick method to determine the potential of both strategies and test new vessel and equipment concepts, which will allow a head start in this upcoming maintenance market.

To determine the three output parameters; CO2eq emission and cost originating from the support vessels and FOWT downtime, a calculation model has been developed, as this was not available. The calculation model compares seven different support fleet configurations for the two maintenance strategies. The configurations contain at least one heavy lift vessel (HLV), platform supply vessel or anchor handling supply vessel type, which are varied in this study on their empirical based parameterised designs. The calculation model also allows the possibility to include, amongst others, preventive maintenance, breakdown maintenance and utilization of different fuels. In total three FOWT farms, varying in size and distance from shore, were considered to determine the effect of those parameters on the different support fleet configurations.

The calculation model was verified and provides a reliable and relatively quick method to compare different support fleet configurations, concerning the two major component replacement strategies. With the use of this model it was found that the most sustainable support fleet configuration for both preventive and breakdown maintenance is a standalone HLV. However, this conclusion does not hold for full blade replacement campaigns. The cost of this HLM strategy is relatively high compared to the TTPM configurations, especially when considering preventive maintenance campaigns. Therefore, it is suggested that the TTPM strategy is preferred for preventive maintenance campaigns. It must be noted that this is also based on the assumption that the port of repair has unlimited facilities to replace the components as soon as the FOWT arrives. It should also be noted that the FOWT downtime is greater for the TTPM strategy, which could be a potentially important aspect of the repair. The calculation model also allows to test new innovative concepts, such as a quick mooring (dis)connection system and the climbing crane. Both show to have a beneficial effect on the replacement operation.

This research has shown that the developed calculation model is well suited, reliable and a relatively quick method determine the potential of both strategies. This research already provided Royal IHC insight into the new market, but can also be used to inform clients who request an advice. The flexibility of the model allows it to be used for different field, fleet and vessel parameters. Moreover, due to the modular programming method additional information can be added at a later stage. This also leads to some recommendations for further research. A suitable weather module has to be introduced in order to get a better estimation on the vessel downtime. After this is done the program should be optimised in terms of runtime efficiency, in such a way that a Monte Carlo method could be run. The added value of this method is that a more accurate support vessel downtime can be estimated. It is also recommended to include bunker time into the calculation as it is currently set to 0 h and potentially leads to an overoptimistic outcome. Lastly, two other floater types should be designed for a 15 MW turbine and included in the model. These floater types are the tension leg platform and barge floater.

The first large offshore wind farms installed in the North Sea Region (NSR) soon reach their technical end of lifetime. The wind turbines in these farms will have to be decommissioned after power production has stopped. Currently offshore wind turbines are decommissioned based on a method called reversed installation, a time consuming and therefore costly operation. This report focuses on the situation regarding decommissioning of offshore wind turbines (excluding foundations), and unveils the possibilities of potential decommissioning methods, using a jack-up, in an effort of to obtain a more cost-effective and environmentally friendly method than the currently used reversed installation. The act of decommissioning is explained, together with the expected market of decommissioning in the North Sea Region. Legislation concerning decommissioning of the five largest offshore wind producing countries in Europe are discussed. Using a multi criteria analysis on demolition methods, floating alternatives, and a model (determining the transport configuration), the most economical and least energy consuming combination is chosen. This model shows an economization of up to 66% and cutting the energy consumption by a third. Lastly, these outcomes are applied to three separate business cases including a sensitivity analysis to show the effect that variations in input values have on the results.

This study aims to provide a proof of concept of a plug-in hybrid electric superyacht. In this way, the yachting industry can help reduce carbon emissions worldwide and potentially increase comfort levels. The concept takes advantage of the typical operating profile of a yacht. A statistical analysis is performed to discretise this and obtain parameters for the all-electric design range at design speed. The available shore power is examined by means of a questionnaire. Three options to compensate the battery weight are presented to minimise impact on design. The resulting concept versions are checked for their potential impacts on four aspects: Design, Sustainability, Comfort and Operation. This includes a life-cycle assessment that results in serious impacts on sustainability at an all-electric range of 2% to 3% of the full range capability. Finally, the concept is tested by means of a test cruise.

Superyachts are large emitters of greenhouse gases, as well as other emissions such as NO_x, SO_x and PM. In order to meet the climate goals set by the IMO, to reduce GHG emissions by 50% in 2050, alternative fuels are being investigated. Methanol is an alternative fuels with great potential. Methanol can be produced completely carbon neutral from biomass or captured CO₂, contains no sulphur, can be stored in liquid form at atmospheric pressure and temperature and can be used in both fuel cells and combustion engines. There are currently no yachts sailing on methanol but methanol has already been implemented in several other ships. Both yacht builders and owners show interest in the implementation of methanol. Since it is unclear which alternative fuel will become the standard on the long term in the yachting industry, it is of interest to also investigate the impact over a longer period of time or of several pathways. Previous research is limited to emissions and costs related to alternative fuels on a limited range of ship types which do not include yachts. The impact of methanol on the design, emissions and costs is still largely unknown for yachts. In order to determine this impact, the properties of methanol, rules & regulations regarding methanol, design impact of the storage of methanol, environmental impact of using methanol and the impact on costs are investigated. To determine this impact for several yachts, a tool has been developed which can be used from the early design stages. The tool uses the properties of a yacht to determine power and fuel volume requirements for the implementation of methanol. It also determines the available volume in the yacht for methanol storage in a basic tank arrangement. Together these form the properties of the yacht with the implementation of methanol. From these properties, the emissions and costs are determined and then combined in a pathway analysis to determine differences in impact of several future pathways. The results show that using methanol generally has a positive impact on emissions, compared to a diesel yacht. Methanol offers SO_x free emissions, a reduction of PM emissions and NO_x emissions equal to that of diesel without the necessity of after treatment. CO₂ emissions slightly increase with fossil methanol but can be net zero with renewable methanol. The impact of methanol on converter and storage costs is considered negligible compared to a diesel yacht. Fuel costs of fossil methanol are slightly higher than fossil diesel, renewable methanol fuel costs are lower than renewable diesel and 5 times higher than fossil methanol. The impact of methanol on the design is relatively large. Compared to diesel, approximately 2.3 times the amount of fuel is required for an equal range. The double bottom is not a feasible location for methanol tanks. A significant amount of interior area is occupied by the fuel tanks and the surrounding cofferdams. Therefore retrofitting existing yachts with methanol is not considered feasible. For new designs, methanol is considered a feasible option.

The urgent development of green energy has become a worldwide trend in the war against the threat of global warming and the impact of extreme weather. The offshore wind farm is one of the solutions that are able to harvest energy sustainably from the environment. To erect these offshore windfarms, the debate about whether a new fleet should be designed and built or make the existed offshore fleet go under retrofitting has been raised. The stakeholder group involved in this issue is formed by the ship designers, ship operators, and market analysts. The difference between the existed offshore support vessel fleet and the offshore wind farm support fleet is the former is built to perform a certain operation and will require another considerable investment to be retrofitted while the latter is looking for solutions to switch from different equipment thus to keep the flexibility between different operation.
The main objective of this research is to propose a ship design methodology to enable the offshore wind farm's request in mission flexibility by improving the design process in the preliminary design phase. Modularity and Knowledge Based Engineering (KBE) are chosen to be the two main topics to support the research objective. To narrow down the research scope, the research object is limited to a small Offshore support Vessel fleet that is able to perform service throughout the lifecycle of an offshore windfarm.
The application of the modularity concept is to break down the vessel system into smaller subsystem or function blocks then reassemble them to be self-sufficient modules. Modules are the basic elements for forming a modular platform to provide a basic model that is able to perform various operations by mounting different equipment. In the former research done in NTNU, a methodology for manipulating the modularity to assemble a product platform by processing previous configuration scripts has been developed. It has greatly reduced the repetitive and iterative works in the design of similar vessels, especially the design for OSVs. Though the configuration scenarios are flexible to change, the pre-designed modules' properties are limited by the based configuration. On the other hand, the configurations are closely tight to the hull shape thus limited the freedom from both the hull design and configuration design. In this research, an improved configuration generator is developed to separate the configuration design and the hull design. The proposed methodology will also keep the flexibility in importing new configurations and the latest hull shapes without conflicts.
Knowledge based engineering is another topic included in this research. It has been proved and widely used in the aerospace industry. As for the ship design industry, the application is limited to local structure design. KBE is a bridge to bring the user and the designer together in the design project. It consists of a programming stage, Knowledge Based System (KBS), to process the selection of suitable design cases and a visualization stage, Computer-Aided Design (CAD) ,to give a direct review on the whole design project. The fundamental drivers for each KBE system are called "High Level Primitive" (HLP). They are the basic units for the knowledge stored in the database. KBS picks out suitable HLPs from the database and assigned them in a configuration script thus forming a design result stored in the digital world. CAD will take over the result and visualize it in the drawing window. This is the proposed methodology to fill the gap between the modularity re-configuration and the diversity of modules.
A Multi-Model-Generator (MMG) will become the final output of this research. It is designed to be able to reproduce several vessels in the OSV market. A further demonstration of the ability to generate a modular OSV product family at the end of the research. Though the modeling output has been proved to meet the index set for the research object, the MMG has the potential to be improved in the future by importing a well-constructed database from the industry.

Offshore wind turbines are designed to persist harsh environmental conditions, including corrosion. Pitting corrosion is one of the most dangerous forms of corrosion. In combination with a fatigue loading, a corrosion pit could result into the failure of a structure, due to a minimal weight reduction. Of the corrosion fatigue process, the transition of a corrosion pit to a fatigue crack is one of the less understood topics. In this thesis, a combined analytical/numerical model is presented that implements mechanisms of both the fatigue, and the corrosion process to determine the moment in time and location in the corrosion pit of the pit-to-crack transition. The hypothesis used to build the model, is that the pit-to-crack transition occurs at the moment that a fatigue crack initiates. Assumptions are made to be able to predict the level of stress and strain at the surface and below the surface of a corrosion pit using a FEM model. Using the stress and strain levels, damage is accumulated until the failure criterion is reached, i.e. when a fatigue crack will initiate. In this research study, elliptical pit shapes are considered, with and without a certain roughness at the surface of the corrosion pit. From the results it is found that a more sharp shaped corrosion pit is a more favourable location for fatigue crack initiation, than a more blunt shaped corrosion pit. The number of cycles to fatigue crack initiation resulting from the developed model are higher, than the number of cycles to failure found by the DNV GL B1 SN-curve for free corrosion conditions. Also, the DNV GL SN-curve is more steep, than a fitted curve through the data points resulting from the developed model. Through a sensitivity study and by considering the number of assumptions and simplifications made in this research study, it is concluded that the spread and uncertainty of the outcome of the developed model is too large to be able to draw conclusions based on the comparison between the results and the DNV GL SN-curves. More research on the input parameters of the developed model will give more certainty and a better validity to the model. It is found that the effect of surface roughness to the fatigue crack initiation life is not substantial, because it affects the stress and strain levels only up to a relatively small depth. The location of fatigue crack initiation is in the pit bottom for blunt shaped corrosion pits, and in the pit wall for sharp shaped corrosion pits. For circular shaped corrosion pits, the difference between the fatigue crack initiation life at the pit wall and the pit bottom is negligible. It is concluded that the model gives a comprehensive basis for the prediction of the pit-to-crack transition, but more (experimental) research on the input parameters will be necessary to be able to give a substantiated estimate of structural life of offshore wind turbine foundations.

To decrease Europe’s harmful emissions, the European Union aims to substantially increase its offshore wind energy capacity. To further develop offshore wind energy, investment in ever-larger construction vessels is necessary. Designing these vessels is difficult however, as this market is characterised by a large but seemingly unpredictable growth of market demand, turbine size and distance from shore. Currently no way of dealing with such market uncertainty within the ship design process was found to exist. This research aims to develop a method that is able to deal with market uncertainty in early ship design by increasing knowledge when design freedom is still high. The method uses uncertainty modelling prior to the requirement definition stage by performing global market research, and during the concept design stage by iteratively co-evolving the vessel design and business case in parallel. The method consists of three parts; simulating an expected market from data, modelling multiple vessel designs, and an uncertainty model that evaluates the performance of the vessels in the market. The case study into offshore wind foundation installation vessels showed that the method can provide valuable insight in the effect of ship design parameters like main dimensions, crane size and ship speed on the performance in an uncertain market. These results were used to create an initial design that is expected to perform well in the uncertain market. The developed method thus provides a way to deal with market uncertainty in the early ship design process.

In the super-yacht industry, value is added by customisation of design. From an engineering perspective, standardisation contributes to working more efficiently and effectively and thus less costly. The perspective of naval architecture company C-Job is that standardisation can contribute to engineering lead time reduction. Since customisation (adding value) and standardisation (reducing costs) are counterparts, a conflict arises when both are aimed for. This thesis proposes a strategy to implement design reuse principles to answer the main research question: How can reuse of design of the non-owner spaces on super-yachts, support reduction of engineering lead time? To provide a substantiated answer to this question three topics are studied. These topics are the design process within C-Job, principles of design reuse and commonalities within existing super-yacht designs. The results of studying the three pillars of this thesis substantiate the proposed solution called the Scale-To-Order strategy. Analysing the design process at C-Job shows that a great portion is consumed by iterating the design to solve all space claim clashes and grid mismatches. Omitting space claim clashes and grid mismatches in an early stage of design would therefore eliminate a significant part of the design process. Reviewing literature on design reuse leads to suggesting the underlying principles of design standardisation, modular design and parametric design for application in the S-T-O strategy. The proposal of using these three principles is based on the commonalities that are found in existing yacht designs. The resulting strategy consists of three stages that follow the kick-off meeting with the future yacht owner. In stage one, principle solutions are chosen, based on the greatest commonalities in existing yachts, that include a typical arrangement below the main deck and a corresponding structural global model and HVAC and sewage principles and routing. In stage two, modifications to the solution chosen in stage one are made if desired. Anticipated modifications can be made modular on beforehand and new modifications can be introduced as modular in the future. Stage three is the scaling of the global model to the desired dimensions and serves as a compliance check for integrity of the model. The goal of the S-T-O strategy is to accommodate engineering lead time reduction in the design phase of super-yachts at C-Job. The expected amount of time saved by employing the strategy is roughly fifty percent of the original concept and basic design phases.

Traceability in complex ship design involves keeping track of the evolving relations between need, requirements and design. Such traceability is not fully developed in the current design process at DMO due to divisions in the design process and between design tools. This thesis proposes to use a single information model to facilitate traceability by connecting the need, requirements and design in a single database. Besides enabling traceability, such an information model can also be used to support modern modelling design tools. In the early design stage of naval vessels – the preliminary design phase – the capability, technical feasibility and affordability of a new ship are defined. Interactions between these three aspects are opaque and rely on the need for a new naval vessel and supporting requirements and preliminary design(s).
Determining the need, requirements and design is in this thesis considered to be a ‘wicked problem’. In such problems, information gained by developing solutions helps define the problem itself. However, these solutions can only be determined with a certain interpretation of the initial problem. This results in many (evolving) interactions between the need, requirements and design in the ship design process as one is needed to define the other. With the help of Systems Engineering and Requirements Engineering information and relations in a ship design process can be determined and structured. These engineering fields are widely applied, and current technology enabled the development of computer aided approaches incorporating design theory, including computer aided traceability. One of the current developments in design approaches is the introduction of model-based approaches, which creates the possibility to actively manage more relations and interactions in the design process. Model based approaches such as the Design Structure Matrix are used to visualise relations between information, and Axiomatic Design enables the decomposition and creation of complex relations. A different approach to modelling in design processes is the use of Knowledge Based Engineering. Knowledge Based Engineering field aims to capture not only the relations and interactions between information in design processes, but also ‘knowledge’ about the ‘how’ and ‘why’ in these processes. Each of these model-based developments relies on, or enables, traceability of information. However, having a program capable of supporting an information storage to support these approaches remains difficult to achieve. For this purpose, Shipbuilder software was created to support transparent storage and management of information. In this thesis, theories for modelling approaches, Systems and Requirements Engineering and the DMO design process have been combined. This resulted in one information structure, applied in the Shipbuilder application, which enables traceability. To show that the proposed information model can model a ship and supports traceability, a case study has been performed. A small model of both an S- and L-frigate has been created to show how traceability can be performed in this information model.

The aim of this research is to create a yacht design for Feadship between 50 and 60 metres that will reduce costs and maintain the customer value. To do so, first, existing yachts are analysed to determine the requirements for the design. Second, an analysis is made of the engineering hours spend on a yacht in this range. Lastly, the engineering process is analysed to determine how the different processes affect the customer value. These three parts form the basis for the design of a modular product platform. The platform is optimised to reduce engineering hours by reusing parts of the design with little customer value and high engineering costs. The result is three platforms and eleven modules to offer the client enough customisation and still reduce the engineering costs. This thesis is made at De Voogt Naval Architects part of the Feadship group.

At Damen’s Research and Development department, continuous improvements are made to existing design practices using recent technological developments and fatigue design is currently on the anvil. High speed craft operating around the globe are subject to millions of load cycles (resulting from ocean waves) and therefore suffer from metal fatigue. As per current practice, such vessels are designed for fatigue using inhouse software with a nominal stress approach supported by static sea-state scatter data and judgement based operational profiles.
Recently, new data sources with real time sea-state data over the whole globe have come available, including GPS locations of ships. Together, this enables it to generate real time operational profiles for its ships. A total stress concept has been developed based on results from a JIP called VOMAS. This approach has shown to provide accurate fatigue lifetime estimates for arc-welded aluminium joints. Similar results are expected for steel joints as well.
The main goal of this thesis was to explore possible improvements for the fatigue design methodology. A tool called Tanaav was developed for this purpose which makes use of both remote monitoring data and the total stress concept and provides an estimate of the yearly fatigue damage and fatigue lifetime. The tool has been used to predict the fatigue lifetime for three fatigue sensitive details in 46 FCS5009 vessels. Results have been compared to corresponding predictions using current and past fatigue analysis practices. It was observed that using both remote monitoring data as well as the total stress concept provides significant improvements in the predicted fatigue life time.
Uncertainties in fatigue influence parameters affecting the predicted fatigue damage can be incorporated using probabilistic. This thesis proposes a method for this and presents two cases as a proof of concept. Work done in this thesis will be validated by Damen in future with the help of full-scale testing on an actual FCS5009 vessel during an offshore measurement campaign. After validation, this method will help in improving fatigue design practice, increasing design flexibility and in optimizing vessel weights in a responsible way.

This thesis investigated the possibility of alternative ways to loading and offloading flexlay vessels and provides a concept design. This was investigated because currently, the vessels designed by IHC, have to sail back to port to restock on pipes. During this time the expensive pipelayer is not laying pipes and thus not making money for its operator. Some operators have already moved to designs which use cranes to load pipes at sea. However, lifting heavy objects results in limited operability and wide vessels. The problem owner (IHC) wants to avoid this. The goal was to find a way to transship pipes offshore, which improves on the current performance of the reference vessel without resorting to cranes to transfer the pipes.

The research was mainly focused on the modelling of the logistical process of getting pipes from the port to the location. The results of this were used for the conceptual design of a flexlay vessel capable of being supplied at sea. The reference vessel built by the problem owner turned out to be a suitable candidate for adaptation for this purpose. To reach this conclusion, a logistical model was made, which was used as a basis for parametric studies. As input to that studies, a seastate timeseries is generated together with different transshipment methods. Two sets of simulations were used to evaluate the effect of the transshipment method in relation to a range of operational limits, and the effect of the distance on the operation.

The resulting pipelayer is fitted with two mailbox type docks in the side, this elongates the vessel and decreases its initial draught. These docks are closed and drained afterwards in order to secure the barge. The main conclusion is that it is possible to redesign the original pipelayer to accommodate the transshipment of pipes offshore.

The international maritime sector accounts for about 2% of all global carbon dioxide (CO2) emissions, the main greenhouse gas that causes global warming. Nations meeting at the United Nations International Maritime Organization (IMO) in London have proposed an initial strategy for the reduction of greenhouse gas (GHG) emissions from ships, setting out to reduce GHG emissions from international shipping by phasing them out as soon as possible with the aim to achieve zero emission by the end of this century. Heerema Marine Contractors (HMC) is a world leading marine contractor in the international offshore energy industry and aims to be a role model in environmental responsibility through carbon emission reductions.

As a result of HMC’s global activities, their fleet covers a considerable distance through transit across the globe. Their large semi-submersible crane vessels are conventionally transported through towing by a tug. The great amounts of fuel required for these transits provides a significant opportunity for the reduction of HMC’s carbon footprint. One such initiative proposed within HMC is the application of wind-assisted ship propulsion on the tow configuration.

This report presents an initial investigation of the feasibility of wind-assisted towing of the HMC’s Thialf, a semi-submersible crane vessel. Previous internal research at HMC showed the feasibility of using a discarded Panamax vessel as a floating breakwater. While operationally the discarded Panamax was found to be feasible, economically this was not the case. In this research, using the Panamax as a wind-assisted tug for towing the Thialf is investigated. As such the Panamax vessel can be employed for multiple purposes; for wind-assisted towing and as a floating breakwater, improving the financial feasibility.

To test the performance of a wind-assisted tow operation, a comprehensive 2D model is developed in this research to be able to check configuration variations in a wind-assisted tow setup. A conceptual design of a Panamax vessel converted into a sailing tug is implemented in a 2D model simulation. The performance in combination with the Thialf is assessed under the common environmental conditions experienced by the Thialf for various transit routes.

Results showed that the use of a wind-assisted tow configuration based on a Panamax, without using the Thialf propulsion is not feasible. The main point of failure is the required force balance transverse to the sailing direction. The Panamax basis used for the preliminary wind- assisted tug design proved to be not the optimal base case due to the limited leeward force generation under a drift angle and the large sensitivity to environmental loading. Although implemented measures improved the systems performance, it is debatable whether a wind- assisted tow configuration with the associated uncertainties is the most promising area to accomplish significant CO2 reductions.

From shallow to deep water, from the well to the ship, from the offshore field to shore or between countries, many kilometres of offshore pipelines for transportation of hydrocarbons (oil and gas) have been installed over the last decades. Allseas’ Tog Mor is a shallow water pipelay barge capable of laying pipes up to a water depth of 25 meters. Currently, Tog Mor is more than forty years old and is due for replacement. Therefore, Allseas has considered to replace Tog Mor with a new shallow water pipelay barge. However, it is unclear whether the current barge is optimised for pipelaying since it is designed for crane supported purposes. The aim of this research is to give insight into vessel properties which determine the pipelaying performances and to define a set of design requirements for the new shallow water pipelay barge, Tog Mor 2.0. To define the requirements of Tog Mor 2.0, the principles of Systems Engineering are followed. Based on the operational analysis, the performances of Tog Mor can be improved by a reduction of the theoretical peak cycle time, optimisations of the pipelaying process and a reduction of downtime. The output of the operational analysis in combination with the principles of pipelaying results in potential bottlenecks. Those performances and potential bottlenecks were the input of the functional definition of Systems Engineering. The aim of this functional definition is to allocate functions to systems and to prioritise the design focus point in terms of functions. Those functions were translated into hardware components and integrated in the total design. Due to the inversely proportional relationship of the number of production days and corresponding production costs, an increased number of stations and lay speed do not have an advantage in terms of costs. In order to reduce the theoretical peak cycle time, the specifications of the functional equipment are improved and the need of buoyancy modules is reduced. Less need of buoyancy modules is achieved by the increased capacity of the tensioner (two tensioners of 100 ton each) and an inner stinger. The pipelaying process is optimised by free deck space, a higher level of redundancy of the functional equipment and new technologies of equipment. The level of redundancy in combination with the improved workability results in a reduction of downtime. Those improvements results in a final concept design which proposes a barge with an off-centre firing-line of five stations (three welding stations, one testing & grit blasting station, one coating station). As a result of an improvement of each individual function and the interactions among those functions, an improvement of 30% in terms of theoretical minimum peak cycle is achieved by an optimisation of the pipelaying process and potential bottlenecks. A reduction of the peak cycle time, an optimised pipelaying process and a reduction of downtime percentages results in an improved overall performance of Tog Mor 2.0 compared to the current Tog Mor.

The data-driven decision support system gives a competitive advantage by the cost-effective improvement of the fleet’s energy efficiency and by the controlled compliance with the IMO Greenhouse Gas Reduction Strategy. The conceptual Business Intelligence Design provides the foundation for data-driven decision support about energy efficiency for the entire Offshore Energy fleet. Boskalis Long Distance Towage department can cost-effectively improve their energy efficiency by 40% toward 2030 with respect to 2008 and thereby fully comply with the outlines of the IMO Greenhouse Gas Reduction Strategy. Boskalis offshore energy is recommanded to implement a Data-driven Decision Support System to manage the cost-effective energy efficiency improvement and the reduction of carbon emission. The organisational awareness and willingness to improve is a prerequisition for successful implementation.

Stolt tankers is the largest operator of deep-sea chemical parcel tankers. Parcel tankers differentiate form bulk chemical tankers by the additional features that the ships have, such as cargo cooling, cargo heating, many (small) cargo tanks, highest level of chemical resistant materials and notation to carry the most dangerous chemicals. These features make the parcel tanker versatile compared to other tanker types, however this results in a higher cost. In the last twenty years, a shift has taken place in the deep-sea chemical shipping industry, driven by changes in regulations, funding of ships and macroeconomic factors. These changes have made the playing field of deep-sea chemical tankers more equal and commoditised, resulting in more competition by entries of new, privately funded companies with simple chemical tankers. Currently a large part of the parcel tanker fleet is nearing their end of lifetime and are expected to be recycled in the next five years. This creates the need to determine operating needs and requirements for replacements of Stolt Tankers’ ageing parcel tanker fleet. The goal of this study is twofold, first, is to determine the need for parcel tanker features in the market and, secondly, to determine the value that these features add. The findings have been concluded in terms of a priority for the feature in a new parcel tanker specification according to the MoSCoW prioritising technique.Analysis of the features is based on D37 parcel tanker class of Stolt Tankers. This typical parcel tanker class is a candidate for recycling in the next 5 years, and therefore a ideal study object for a replacement study. Four features were identified as giving the highest differentiation of a parcel tanker and are analysed in more detail: cargo cooling, cargo heating with thermal oil heating medium, small cargo tanks, and ship type 1notation. These features are analysed both qualitatively and qualitatively on its operation in the Stolt fleet, market demand and supply, competition and alternatives. The net added value of the features over the life of the ship has been calculated by means of a discounted cash flow analysis for base-,best and worst case scenarios.The cargo cooling feature yields the best added value for a new parcel tanker. The thermal oil cargo heating feature has a negative added net present value for only cargoes with this specific requirement. The study of the ship type notation has a low investment cost, however the loss of revenue by the capacity reduction is far more than potential revenues from thetype 1 cargoes. The number of cargo tanks has a large impact of the capital cost of the ship.Reducing the number of cargo tanks, i.e. the average tank size, yields a relatively large savingfor parcel tanker ship types. Combined with a decrease in the number of small cargoes, makes this a logical development for future parcel tankers. However, more research is required since there is a large discrepancy between the number of small cargoes on different trade routes.Based on the findings from the market and operational review of the D37 features the following priorities are given to the features. The cargo cooling system has been given a’Should Have’priority, the thermal oil cargo heating system has a’Could Have’and the ship type 1 notation a’Won’t Have’. Further research is recommended for the requirement of features of new ships with respect to the total fleet of Stolt Tankers. Secondly, modelling of cargo tank layouts with the statistical trading data is recommended to determine the requirements for the number and sizes ranges of cargo tanks