The accessibility in far offshore wind farms during unplanned maintenance is reported to be insufficient. This system largely consists of daughter craft, small vessels that increase the multitasking capabilities of an SOV. The goal of this research is to improve the accessibility to ultimately increase turbine availability, which is proven in this work to be necessary. The research is carried out in cooperation with Siemens Gamesa, a major wind turbine supplier. This research builds off the basis laid by Brans et al., who applied a needs analysis on the daughter craft system. This research applies the next step in the systems engineering sequence: concept exploration. The scope of this research extends beyond that of the daughter craft to any system that can improve the unplanned maintenance of far offshore wind farms.

Because the subject matter is relatively little covered in the scientific field, this research lays great emphasis on the context of the problem. The status quo of the sector is described in terms of equipment, operations, regulations, forms of limitations, financial context, trends, and different stages performed in unplanned maintenance. By performing an analysis of alternatives a high potential for system improvement is found.

A set of performance requirements for the accessibility system is developed to structurally assess the system and possible improvements. These performance requirements are used to determine which alternative system holds the most potential for accessibility improvement. Increasing daughter craft dimensions is chosen as the most potent alternative. A feasibility study is performed on deploying CTV-sized vessels far-offshore for two weeks thereby significantly reducing transfer time and distance. These vessels are called far-offshore transfer vessels (FOTV).
Different configurations are tested for storing the FOTVs far-offshore when not in operation and interfacing with the SOV. Two principal concepts are identified: Enlarged daughter craft, where the FOTV is stored on the SOV, and the exposed principals, where the FOTV remains in the water. One configuration of the enlarged daughter craft principal is deemed feasible: The lifting launch configuration. Two configurations of the exposed principal are deemed feasible: The connected to the SOV configuration and the moored to designated platform configuration. Furthermore, a model is constructed to assess the logistic and economic merit of different combinations of FOTV, wind farm, and configuration.

This research concludes that the deployment of a FOTV combined with a lifting launch configuration is most profitable for any wind farm. Nonetheless, the exposed principal concepts outperform the current system significantly. The choice of FOTV depends mainly on the accessibility performance and day rate of the vessel but also on the wind farm. The model predicts that in the current market, the highest-performing CTVs are the most profitable options for FOTV deployment. Finally, the results show that the effects of improving accessibility vessel performance relates inverse exponentially to profit performance. ... Read more

Climate change and greenhouse gas emissions have been at the forefront of both public and academic debate for some years. Although the shipping industry has managed to remain relatively free of climate regulation this is changing with the IMO goals for 2050. The military sector has also escaped scrutiny on sustainability issues. But this is also changing as the Dutch Ministry of Defence expressed the ambition to reduce its carbon footprint, with the eventual goal to reduce the operational dependency on a scarce resource, and to comply with national and international regulation. The direct aim, therefore, is to reduce the fossil fuel consumption by 70%, and to comply with IMO regulations by 2050.
In this thesis the possibilities for reducing fossil fuel consumption and greenhouse gas emissions will be examined. This will be done for the seagoing large surface vessels of the Royal Netherlands Navy by using alternative fuels.
This question is answered through the execution of two case studies of vessels with different mission profiles: the Zeven Provinciën class Air Defence and Command Frigate and the Landing Platform Dock Johan de Witt. For both vessels, a design process is carried out in which more detail is progressively
added whilst down selecting the most suitable technologies.
The first step in the design process is an operational analysis. This operational analysis uses the perceived missions profiles and the RNLN maritime doctrine to make a prioritization in a set of technical properties or measures of effectiveness. In the second design step, a systematic design variation is used to estimate the effect that different energy carriers have on the main dimensions of the vessel. The parametric design tool developed for this is an adapted version of the SPEC tool developed by Marin. The model estimates the required power and the weight of different weight groups of the vessel. The final design step continues with a more detailed proposal for a power plant configuration for both case studies. With this detailed design a final assessment of the fuel consumption, exhaust gas emissions, and operational effectiveness is made.
Throughout the design phases it was established that the displacement of both vessels would increase significantly due to the lower energy density of the selected fuels. In the case of the Air Defence and Command Frigate, the high top speed and relatively high fuel and system weight lead to a larger increase in required fuel and installed power due to the increasing resistance when using anything but the most energy dense fuels. For the Landing Platform Dock, which has a more modest power requirement and a relatively low system and fuel weight, the increase in displacement is smaller. In conclusion, it can be said that the goals stipulated by the Ministry of Defence are attainable. The effect on the operational effectiveness varies between vessels but the overall fuel consumption, cost, and displacement are sure to increase significantly. ... Read more

Design decisions which are made in the preliminary ship design phase have a significant influence on the performance and total cost of a ship. These design decisions are mostly made with very little knowledge of the ship design problem. In fact, it is the personal experience of the naval architect which plays a significant role in this phase of the design process. In the world of rapidly increasing possibilities with artificial intelligence it is hard to imagine that these decisive design choices are based on a naval architect’s personal experience. Especially when one takes into account the large capital and operational costs of ships. The development of C-Job’s Maritime Intelligence Tool (MIT) in 2019 has shown that reference data can better be exploited in this phase of the ship design process. As a result, theoretical reductions of the resistance and weight of the vessel go up to 19% and 10% respectively, using this tool. When the availability of reference data is limited, the trustworthiness of this tool cannot be guaranteed. This is especially unfavorable at the boundaries of a design space, as it is expected that novel and innovative ship design can be found here. Thus, in order to support naval architects in all regions of a design space, a solution must be found. First, research is done into design approaches in the preliminary ship design phase. In this research, naval architects of C-Job with different backgrounds were interviewed. During these interviews it became clear that time, budget and customer ambitions are important motives in this phase. As a result, a lot of ship design decisions in the preliminary ship design phase are based on the naval architect’s personal experience. The more the design is developed, the more insight is gained into the complexity of that ship design. As a result,more design decisions could be based on this gained insight, instead of the personal experience. During these interviews, challenges were identified and discussed that the naval architects face, before the Maritime Intelligence tool can be used in practice. Based on these challenges a list of tool requirements was determined and potential solutions were sought. Three solutions were found to be promising for this thesis. These were serial hybrid modelling, parallel hybrid modelling and constrained black box identification. The parallel hybrid model is chosen, primarily because of the independent operations of the data-driven sub-model (Black Box model) and the knowledge-driven sub-model (White Box model) in a parallel hybrid model. There are two requirements for parallel hybrid modelling. The first requirement is a method to estimate a ship design parameter. The second requirement is the availability of the true values of the same design parameter of reference vessels. These were both only available for the design parameter lightship weight. In the proposed parallel hybrid model, the white box model is used to estimate the lightship weight. Thereafter the black box model is trained to predict the difference between this estimation and the actual lightship weight, based on reference data. The proposed parallel hybrid model is subjected to multiple experiments to assess the performance. The R2-score and 10-fold cross validation are used to determine the performance. First the performance of the white box, black box and parallel hybrid model is discussed. Thereafter, the relation between the availability of reference data and the predicting capability is researched. The final experiment was to research the performance of the three different models in interpolation and extrapolation gaps. Based on these experiments it was concluded that for a training data set of 50 reference vessels or smaller, the parallel hybrid model was the best model. For larger training data sets, the black box and parallel hybrid model performed similarly. For interpolation and extrapolation problems the white box model should be chosen. Additionally, a method is presented to update the used white box model. As a result, it is expected that high performance scores can also be obtained without the use of artificial intelligence tools. ... Read more

New offshore wind farms are moving farther away from the shore; to locations characterised by adverse weather conditions. This challenges current maintenance strategies because, besides being further from shore, far-offshore wind turbines need more frequent maintenance and must be accessed in rougher weather conditions. Service Operation Vessels provide high accessibility to far-offshore wind turbines, but they lack multitasking capabilities. Its daughter craft is a valuable asset for unplanned maintenance in the summer when it can operate safely, but it is often not deployable during the winter due to the rougher weather conditions. The main research question is: What are the deficiencies of current DCs, and how can these access vessels be modified to operate year-round at far-offshore wind farms? The results show that the current DC’s deficiencies lie in its current operational requirements. Also, performance in oblique waves is currently riskiest since that is when there are higher vertical accelerations or a combination of vertical and lateral accelerations. Furthermore, wave steepness has significantly more effect on accelerations that wave height. Lastly, future DC designs should be focussed on stable seakeeping performance during transfers rather than high-speed transit. An analysis into the seakeeping performance of four prototypes showed that it is feasible to increase the transfer requirement from Hs ≤ 1.5 m to 2.0 m ≤ Hs ≤ 2.5 m. The catamaran type DCs have a high potential to realise year-round accessibility to far-offshore wind farms due to their resulting performance in oblique waves. ... Read more

This study aims to develop a decision support tool which enables shipowners to select the most appropriate alternative fuel technology to comply with possible different imposed emission regulations while ensuring optimal business performance. In this context, most appropriate is defined as a fuel alternative which minimises required freight rate (RFR) while maximising overall performance on technological, environmental and other criteria. A decision support tool was devised combining a decision model based on the simple multi-attribute rating technique (SMART) with a financial model based on discounted cash-flow (DCF). Additionally, an optimisation model was implemented to optimise for minimal required freight rate through slow steaming. The decision tool provides shipowners with a quantified impact on their current business if they do not transition to alternative fuels under a 'market based measure' (MBM) regulatory scenario, as well as best-alternatives if their current fuels do not meet regulations under an 'emission cap' (EC) scenario. The decision tool is evaluated under optimistic, average and pessimistic scenarios in 2020, 2030 and 2050. Under an emission cap scenario, the results showed an overall preference for Fischer-Tropsch diesel (FTD) as the most promising alternative maritime fuel both in terms of SMART performance and required freight rate, followed by upgraded bio-oil (UBO). Nevertheless, the average difference in required freight rate of alternative fuels compared to HFO remains substantial, at 43% and 38% higher for Fischer-Tropsch diesel under a 'no regulation' scenario and 'market based measures' scenario, respectively. It is therefore evident that without regulatory intervention, heavy fuel oil is expected to retain dominance based on cost. Even under a market based measure (MBM) scenario, the average required freight rate of HFO increases only by 3.4% overall. For LNG, market-based measures lead to an average increase in RFR of 4.1%. These results suggest that in order for the maritime industry to transition towards sustainable alternative fuels, policymakers, governments, international organisations and lenders need to align their policies to collectively enable a more sustainable shipping industry - not only by enforcing stricter regulations, but also by providing the correct financial incentives. ... Read more

Within this thesis an attempt is made to improve the seakeeping of a Service Operation Vessel (SOV) by means of an active anti-roll tank (ART). It is researched if the addition of a wave prediction system can improve the ART’s performance. As the seakeeping of the SOV is most important for the installed motion compensated gangway, the workability is assessed for different control methods based on the design criteria of the gangway. The computations have been made in frequency domain. A one directional model is used with two degrees of freedom: the ship roll angle and the tank’s fluid angle. Due to the presence of a wave prediction system, a feed forward loop can be introduced in the control system. It is found that if the pump moment leads the wave excitation moment, the tank’s fluid will oscillate in a less power demanding way. This is caused by the better interaction of the action and reaction forces that are caused by the pump. The action force on the ship’s structure will always oppose the wave moment, but the force acting on the tank’s fluid will only stabilise the vessel at certain frequencies. To obtain a robust model, the feed forward loop is combined with a feedback controlled model. The stability of the models’ feedback loop is assessed using Nyquist plots and sensitivity plots. It is found that for the damping factor belonging to the ART of the SOV, the feedback loop is unconditionally stable. On topic of the powers related to the active ART the dissipated and actual power are analysed. Based on the dissipated powers it is found that for the same amount of dissipated power by the pump, the feed forward controlled model causes a lower root mean square value of the ship’s roll in comparison with the feedback controlled model. This is explained by the better interaction of the forces generated by the pump. Based on the obtained RAO for the roll motion, the workability of the SOV is assessed for a significant wave height of 3m. It is found that even though the seakeeping of the vessel increases because the roll response decreases, the gangway motions aren’t significantly affected by the active control of the ART. The reduction in roll response is not proportional to the reduction of the gangway motions since other vessel motions such as heave and sway also effect the gangway’s motions. All in all, it is concluded that adding a feed forward loop to a feedback controlled model improves the seakeeping of the SOV. However, to improve the workability of the SOV it is recommended to include a passive ART in the design, instead of an active ART. This is because the active control has little impact on the gangway’s motions compared to the passive ART. ... Read more

This thesis describes the process of selecting different greenhouse gas emission reduction technologies for the application on a redesign of a multi-purpose heavy-lift vessel. Only technologies were considered which did not negatively influence the operability or arrangement of the redesign. The best performing combination of technologies was identified using performance indicators which measured the economic and GHG emission reduction performance. The best performing combination of GHG emission reduction technologies results in an emission reduction potential of 20.6% compared to the currently operated vessel. It is concluded from this study that when only considering technologies on a redesign of a multi-purpose heavy-lift vessel which do not negatively influence the operability or arrangement, the IMO GHG emission reduction goals cannot be met. ... Read more

The ongoing demand for bigger and more efficient ships pushes their designs towards the strength limits. Sometimes, ship structures are pushed beyond their limits with the possibility of significant negative economic and environmental impact or, in the worst case, impact on human life. This makes it explicitly clear why the development of accurate methods and models is still required to predict if a design can withstand the expected loads during its operations. In the past two decades, Machine Learning (ML) has been applied in the field of structural design. Still, the amount of research regarding the scalability and generalizability of ML within structural design is limited. This research aims to investigate the use, scalability, and generalizability of ML to predict the ultimate strength of stiffened panels. A large dataset of stiffened panels loaded under longitudinal uni-axial compression and lateral pressure is generated. This set is based on a representative geometrical parameter set in shipbuilding obtained by the optimization of an analytical buckling model for stiffened panels. This model incorporates several nonlinearities such as initial deflection, large deflection theory, and residual stress. Finite Element Analysis (FEA) is used to obtain the ultimate strength and stress distribution at the moment of failure for every stiffened panel. This data is used to train two Convolutional Neural Networks (CNN) to predict the ultimate strength and stress distribution at the moment of failure. Overall, the CNNs are an excellent tool for these predictions when sufficient data is available, the data shows substantial geometrical similarity to the training data, and when the data is within the scope of training. When predicting the ultimate strength of the stiffened panels in this research, it is required to have at least 4000 data samples to obtain a well-trained network. The scalability of the ultimate strength predictions produces acceptable results within the 5% margin of the training scope. Unstable prediction behavior is observed when predicting stress distributions. Both the ultimate strength and stress predicting models are also trained on stiffened panels curved in the transverse direction to test the generalizability of the CNNs. Poor predictive capabilities were observed when predicting the ultimate strength and stress distributions of the curved plates. The use of ML in structural engineering proves a useful concept and provides multiple opportunities for further research. ... Read more

Naval ships need to be able to conduct missions in a variety of circumstances. This includes the ability to fulfil specific tasks in a damaged state. Vulnerability reduction measures are taken during the early stage distributed ship system design process, to ensure the availability of the required systems in damaged state. Traditionally these vulnerability reduction measures are based on design rules or best practices resulting from past experiences. Therefore the measures are not per definition applicable for future warships, as both the system concepts and operational environment changes. Recently developed vulnerability assessment methods are able to determine the vulnerability of a design early in the design process. With integration of these methods in the early stage design process, the results of the analysis can be used to generate less vulnerable distributed ship system designs. This thesis proposes an integral and holistic approach of optimization of the design variables and distributed networks as these are becoming increasingly interdependent. The result of this approach is a model which generates distributed ship system designs consisting of component positions, a topology and routed connections based on a pre-defined system configuration and constraining physical architecture. Five testcases were conducted using this model, showing the necessity of the integral and holistic approach as the extent to which the contemporary design rules are implemented depends on the network complexity and operational environment. The developed method assists the naval architect in generating designs and requirement elucidation in the concept exploration stage. ... Read more

This thesis presents the potential of solar energy to answer the increasing demand for sustainable energy. Multiple floating solar parks are installed on inland water bodies. This trend is a result of the lack of surface for PV systems and a result of legislation on national and international governmental levels, for the reduction of greenhouse gasses. This inland technology is currently well established. Still, in densely populated areas such as the Netherlands supplementary surface could be beneficial to unlock the full potential of solar energy. Ocean and sea surfaces are a possible, but challenging solution to this problem. These offshore water surfaces could be used for electricity or synthetic fuel production. Offshore locations are attractive because of the abundant availability of surface. Still, an OFPV-system needs to overcome multiple technical and non-technical challenges and requirements. This challenge demands technical solution within the constraints of a suitable business case. Furthermore, the impact on people and ecology also needs to stay within ethical borders. An OFPV can be subdivided into three physical subsystems: an energy converting system, a position monitoring or mooring system and a floating support structure. Multiple concepts were proposed in literature or by the industry. All proposed concepts are variations of support systems that provide a surface for conventional PV-technology. It also was concluded that none of the proposed concepts is fully developed. Currently, only one system is in the testing phase. The current state of the technology, and the high potential of an OFPV are the drivers behind the search for a new concept design. In this thesis, the requirements for an OFPV support structure were formulated, and a brainstorm resulted in the buoy and beam concept for further research. The buoy and beam structure is a system in which submerged beams form a triangle grid are held together by floating buoys. The buoys support triangle platforms, by carrying the corners of the platforms. All connections between the buoys, beams and platforms are fully hinged. Because of the hinges, the structure can move with the waves and therefore mitigates the loads it experiences. In the second part of this thesis, the feasibility of the buoy and beam structure was assessed. It was concluded that the heave response is the most critical response to the feasibility of the concept. When the platform would heave too much, the waves will slam into the platforms and the solar panels, leading to damage and excessive loads on the structure. Consequently, the heave response and the relative wave height seen from the moving triangle platform are researches and modelled. The structure was identified as a hydrodynamic transparent structure. Consequently, the relevant hydrodynamic loads are obtained with the Morison equation and Airy wave theory. All damping terms are linearised. A differential equation incorporated the constrains for both, the construction and the hydromechanic loads. The mechanical equations can be linearised by assuming small angular displacements of the beams. This differential equation is implemented in a calculation tool in MATLAB. The code is verified over multiple steps. The tool made it possible to obtain the response based on the topology and the main dimensions of the buoys and the beams. With this calculation tool relations between the dimensions of the buoys and beams on one side and the frequency response, on the other hand, are identified by simulating different variations of a simplified starting design. The following conclusions were made on the eigenfrequencies. Firstly, it was noted that the eigenfrequencies of the system are in proximity to each other. Secondly, it was shown that the first and second eigenfrequency could be calculated in a simplified manner. Thirdly, it was seen that the buoy diameter to mass ratio has a positive linear correlation with respect to the eigenfrequency, i.e. the stiffness to mass ratio of the system severely influences the eigenfrequency. Furthermore, it was seen that an increasing beam length has a slight linear correlation with the eigenfrequency. Also, it was concluded that a large hexagon system (for example, nineteen buoys) could be beneficial because a hexagon structure creates a large surface with respect to the number of buoys. Moreover, in reality, the response should be lower than the model prediction, as a result of the high number of beams that cause damping. Additionally, a hexagon system should have a minimal change in response for different incoming wave angle. To obtain a feasible system, the response peaks of the structure should not overlap with the wave spectrum. Based on the additional simulation, it was concluded that it should be possible to design a system with a low eigenfrequency resulting in a system that will only slightly move with the waves. Additional relations between the dimensions of the buoys and beams and the response peaks were found. The requirements to obtain a low eigenfrequency and a modest response match, which positively influences the feasibility. Some further steps on the research of the heave response and the relative wave height are needed. The calculation tool can still be improved. A preciser estimation of the response peaks is of significant importance. Some further iterations must be executed to determine the full potential and feasibility of the concept design. Furthermore, in a scientific point of view, it will be highly interesting to validate the model on a model scale. In the development of the buoy and beam structure, additional critical responses need to be researched. The forces in the hinges and the response in horizontal direction need to be known for further assessment of the feasibility. Next to the technical aspects, the human, ecological and economic implications of the buoy and beam structure need to be researched. ... Read more

Trim optimization is an approach considered by the industry to improve the energy efficiency of ships, having a potential in both reducing operational costs and to decrease the emissions of the ship. Potential fuel consumption reduction by trim optimization is 0.5 to 3 % and to up to 7% in extreme cases. Stolt Tankers, a shipping company active in the chemical tanker market, wants to increase the energy efficiency of their ships in operation by trim optimization. For a limited number of ships, trim tables from model scale towing tests are available, but these are not used and the accuracy of these tables are unknown. The objective of this research was to develop a method to decrease fuel consumption by trim optimization, by a dynamic fuel consumption estimation model based on available operational data, that can be integrated in the voyage management system of Stolt Tankers. A dynamic fuel consumption estimation model has been developed, using mainly the noon report data of the C-38 ship class, consisting of six sister vessels of 38 000 DWT chemical tankers. Quality of noon report data is an issue: human error in observing and recording data causes noise and a mismatch exists between the snapshot of conditions on one hand, and the 24 hr averaged sailing speed and recorded shaft power or fuel consumption on the other hand. A data pre-processing framework has been developed and applied to integrate and transform the data, clean and filter the data. The model is able to extract the effects of speed through water, mean draft, trim, sea water temperature, wind force, sea state and swell state and their relative direction to the ship and days since last hull cleaning and propeller polishing. The model has shown to perform optimal using the regression model of Lutzen and Kristensen (2013), combined with a multiple layer feed-forward neural network, consisting of 1 hidden layer with 15 neurons. The model is able to estimate the shaft power with an average accuracy of 6.58 % for a random test set of the noon report data. It is able to extract the effect of trim on shaft power and to consider the effect of weather and fouling conditions. Model results show that about 1 to 2% of shaft power per 0.50 m can be saved, with trim by bow being the optimal trim. Based on sea trial results, it is concluded that the model performs most accurate for conditions that are represented by a high quantity of historical data. The model can be applied for speeds between 12 and 14 knots and for mean draft conditions of 9.5 m and more. Within this range, the effect of trim and weather conditions are followed with reasonable accuracy. It is confirmed by the sea trial that trim by bow is the optimal trim, with a much stronger magnitude of the effect of trim on shaft power. A difference of 6 to 8% in shaft power was found for a change in trim of 0.50 m. ... Read more

The common practice of designing a ship is to look for ships with similar specifications and alter it to the client's needs. This often leads to structurally redundant and therefore overdimensioned ship designs. Hence, much improvement could be expected from ship structures where optimization algorithms help advise in the design process. In this research, the midsection of a Trailing Suction Hopper Dredger (TSHD) is optimized. A TSHD midsection generally consists of longitudinal stiffened panels and transverse web frames. The typical web frame and longitudinal stiffener layout is optimized, as a weight improvement of this section can have a large effect on the total weight of the ship since it is repeatedly reoccurring.

This research has optimized the midsection of a reference TSHD in two ways; the first step was to perform a shape optimization for the longitudinal stiffener arrangement, which was followed by a topology optimization for the transverse web frame. Both optimization objectives were to minimize mass. The order of optimization follows the hierarchy in which stresses are introduced into the structure; from the plates that make up the hull toward the stiffeners and eventually the web frames. The complete optimization was performed a total of seven times, for seven different web frame spacings ranging from 25% to 175% of the web frame spacing of the reference TSHD.

For the shape optimization, a Simulated Annealing algorithm was used. The reference ship was simplified to be able to parameterize the geometry into eleven panels with T-stiffeners. Each panel has a set of variables that describe its geometry; the plate thickness, number of stiffeners, stiffener web height, flange width and web and flange thicknesses. Although feasible results came out of the optimization, no clear parallel was found when comparing the plates of different web frame spacings. This is due to the fact that it is a high dimensional problem. Although no clear parallels were found, the results were able to cope with all the loads.

The topology optimization was performed with a modified Bi-directional Evolutionary Structural Optimization (MBESO) method. The applied modifications ensure a fast convergence for large topology optimization problems. The new method was first verified by comparing results to two benchmark cases from the original BESO method, which was followed by three examples of common topology optimization benchmarks. Once established that the modified method was capable of reproducing test cases, an aspect ratio analysis was performed to better understand the transmission of stress. After that, the full geometry of the midsection was divided into smaller basic models and the same optimization was carried out in order to help interpret underlying physics of the final results. Finally, the topology optimizations for the seven web frame spacings were performed, resulting in a new orientation of beams. The topology optimization results showed that constructing beams not in an orthogonal way and along the ship hull but rather under various angles could reduce the total mass of the web frame.

To see how the shape optimization result influenced the topology optimization, three studies were carried out where all the surrounding plates had the same thickness, except for one that would have a significant smaller thickness. This showed how the web frame supports the hull plating, but also how the web frame is dependent on the stiffness of certain panels to be able to transfer shear into them.

Finally a comparison was made between the reference ship and the optimized structure. The result was a decrease of 23\% in weight for the midsection. Due to practical production considerations this weight is likely to be higher in practice, however it is a promising start toward a more efficient ship design. The innovative combination of shape optimization combined with the MBESO procedure could help in early design stages where the main components of the construction are defined. ... Read more

Damen Shipyards Gorinchem has found deficiencies in the process of developing concept designs of Offshore Patrol Vessels (OPVs). There is a need to increase the efficiency of this process, meaning that (1) the speed has to be increased, (2) the accuracy of designs has to be increased and (3) the risk of deviations of the project plan has to be reduced. Analysis of the current concept design phase shows that the designer should get more insight in the design challenge, and that a more systematic and uniform design approach is required amongst different involved departments. Additionally, the lead time of developing concept designs is mostly delayed by two major bottlenecks: development of the hull shape and obtaining a resistance prediction. In this thesis a conceptual design tool is developed to resolve these deficiencies, by providing a platform for fast hull concept exploration. Key of this approach is to pre-compute time-intensive design aspects such that the most critical activities are done before starting the design process. It uses a set of parent hulls for which the resistance is obtained by RANS CFD simulations. Based on the parents, a semi-parametric modelling technique is used to create new hull geometry. A kriging surrogate model is used to provide a RANS CFD resistance prediction to that new hull geometry. A brute-force approach is then adopted to fill a database with feasible hull shapes, which can be used by the conceptual design tool for hull shape concept exploration. To test this concept a proof-of-concept database of 245.005 hulls of double-ended ferries is generated in a few days on a laptop with good memory capabilities. The geometry results and resistance predictions in the database have been assessed with a sensitivity study, cross-validation and comparison with the parent hulls. It is shown that resulting geometry is smooth and well-faired. The resistance results are sufficiently accurate for use in the concept design phase, but applicability is limited for low prismatic coefficients. For application to OPVs further research into application of this approach to hull geometries with varying local details (bulb shape, tunnels etc.) is necessary. The approach seems promising to improve the concept design phase, as it (1) reduces time pressure in the design process significantly, (2) provides insight in how the resistance is affected by main dimensions of the vessel, and (3) reduces the number of departments which is actively involved in the design process. Putting the design tool in practice should reveal if this is indeed the case. ... Read more

The International Maritime Organization forecasts that greenhouse gasses produced by ships will increase rapidly in the near future, unless precautions are taken now. This will require all ships to reduce their emissions, especially container vessels which are producing the most emissions. One way of reducing emissions, with existing technology, is to switch to alternative fuels. Making this switch is risky as there are many economic and regulatory uncertainties, which the ship has to survive over its lifetime. This makes it difficult to see which alternative fuel is a better option or not. There is no existing study which makes a comparison between alternative fuels which also takes future uncertainty into account. The aim of this study is to develop an approach to assess alternative fuel types for robust ultra large container vessels, while taking economic and regulatory uncertainty into account. For this purpose, Robust Decision Making was chosen as the most suitable method. A method which has been used in different areas, but will be implemented for the first time for a subject relating to ship design. Implementing this method required the development of a parametric design tool for ultra large container vessels. Results show that liquefied natural gas is the most robust option amongst the considered alternative fuels. It would have a good economic performance, while reducing emissions. Non-carbon fuels, such as hydrogen and ammonia, would practically eliminate emissions but do not perform well financially. ... Read more

The use of renewable energy sources like solar and wind energy for the generation of electricity are expected to increase in the coming decades. However, these sources are intermittent. Therefore Electrical Energy Storage (EES) systems are needed in the near future to assure a reliable electricity supply. These systems should also be able to deliver power in longer periods of time with low generation from wind and solar energy sources. An example of such an EES system is the GreenBattery, developed by AquaBattery. This is a flow battery that stores the electricity by splitting salt water in an acid and a base. Because the main component of the GreenBattery is salt water, this battery is safe in use, as it cannot catch fire or explode. Furthermore, this makes the battery environmentally benign and cost competitive with other EES systems. The main focus of this thesis is to make a concept design of a GreenBattery that can be placed on a water like a lake. This concept is evaluated in a case study regarding the energy storage lake of the Delta21 project. This battery could provide a reliable backup electricity source for e.g. the Port of Rotterdam or stabilise the electricity output of renewable sources. Therefore, the main research question of this thesis is: ‘How can AquaBattery’s GreenBattery be realised on the energy storage lake of the Delta21 project, providing long term storage?’ To answer this question, first the design basis is explored. Based on this, concepts are generated using a morphological chart method and the most feasible concept is chosen using a multi-criteria analysis. This chosen concept is worked out in more detail, after which its technical and economic feasibility is investigated. The most feasible concept turned out to be a floating concept. This concept uses floating rigid tanks to store the different liquids present in the GreenBattery. The power unit, where the electricity conversion takes place, is placed on top of these tanks. Furthermore, the feasibility of integrating a solar photovoltaic system on the floating tanks is investigated, because of the large area available for multiuse on such an island. The resulting dimensions of the floating tanks is 98 by 98 by 3 m (length, width, draft). Four of these tanks can be coupled together to form one floating island. Such an island can store about 560 - 800 MWh of energy, depending on the required storage duration and about 3.2 MWp of solar panels can be placed on top of the tanks. In total, about 300 of such islands can be placed on the energy storage lake of the Delta21 project. Such an island is technically feasible, because the natural periods are larger than the expected wave periods. Therefore, the motions and forces of the island will be minimal. Furthermore, in terms of costs, the floating GreenBattery is cost competitive with other EES systems and therefore will be economically feasible as well. ... Read more

Maritime transport covers about 90%of world trade and is seen as one of the most cost-effective way of transporting goods. In order to safely accommodate vessels calling into ports, tugs are operated to assist various sized vessels with navigating, manoeuvring and berthing. Competition within the ship handling market has always been fierce. Boskalis Towage, through a network of joint ventures, offers harbour- and terminal towage services around the world, comprised of about 450 vessels. Operating a large fleet comes large Operating Expenses (OPEX). In order to deliver a more cost-effective service, Boskalis turns to business intelligence (BI) to help with the decision-making process. Maintenance is crucial for the operation of the vessels, but also a large part of the expenses. Large deviations in maintenance costs and operational performance exist between the joint ventures. However, the reasons behind these deviations are yet unclear due to the absence of continuous monitoring capabilities. The objective is therefore to increase the management capabilities of detailed performance monitoring of M&R expenses and performance of tugs, through which possible improvements can be determined. The M&R of tugs is influenced by various factors, such as utilisation, operational location and installed equipment. This research has evaluated the current Enterprise Performance Management (EPM) of Boskalis Towage and used literature on Maintenance Performance Management (MPM) in order to erect a multi-criteria hierarchical function-specific framework which is a framework for maintenance performance monitoring. The presented framework covers aspects of alignment with business objectives and plan, strategy and implementation. Moreover, the framework presents the maintenance function and its areas of performance measuring of equipment-, cost- and process performance across the organisational hierarchy. By performing a regression analysis of the maintenance data, this has also resulted in an increased understanding of the relationship between maintenance costs, operational data and vessel characteristics. As a result, an equation with acceptable statistical accuracy for running repairs has been found. The implementing of the MPM framework on the maintenance of tugs has resulted in the MPM model. This model focuses on the running repairs and dry docking direct costs and activities, incorporating basic maintenance types, i.e. Preventive Maintenance (PM) and Corrective Maintenance (CM). Running repairs have been evaluated in the time domain while the evaluation of dry dockings have been evaluated as events due to their relationship with regulatory surveys. The model incorporates operational-, maintenance- and financial data, tug specifications and operational conditions in order to evaluate maintenance performance. Maintenance Performance Indicators (MPIs) have been established to determine deviations and deficiencies among the different aspects of M&R. Challenges were faced on the aspects of data quality and data management, especially in the areas of maintenance process. The model has been validated through a detailed evaluation of five selected tugs. The underlying reasons for the underperformance of these tugs have been found and verified with knowledgable bodies and thus validating the model and its ability to determine underperformance and deviations. An alternative performance analysis method, Data Envelopment Analysis (DEA), has been researched and shows promise. The Slack-Based Measure (SBM) DEA model is a non-parametric frontier approach, based on Linear Programming (LP), to evaluate performance based on slacks (room for improvement) of Decision Making Units (DMUs). The method is capable of determining similarities in inefficiency in maintenance performance, comparing it to results from the MPM model. It, therefore, proves the method is capable of quick evaluation of maintenance performance and of determining new maintenance targets. However, the model is simplistic and requires further detailing and is unable to determine underlying reasons for underperformance. The regression equation and DEA have been used to formulate a so-called performance region which describes the lower- and upper bounds of the running repair costs for individual tugs. Unfortunately, data quality doesn’t allow for the determining of these bounds for all vessels nor for dry docking. New key benchmarking targets have been established through quartile values for respective Maintenance Performance Indicators (MPIs). With this newly obtained knowledge, future maintenance performance evaluation of tugs can now be performed with a higher detail through analysis conducted with the developed MPM model. ... Read more

The negative effects of global warming can already be noticed. The burning of fossil fuel not only contributes to global warming, but also to the reduction of air quality, especially in urban areas. In order to limit the climate change, as well as to improve the air quality, more and more vehicles are replaced by emission free versions. This thesis is a case study in which the feasibility of replacing a fast passenger ferry (300 passengers, 30 knots) by an emission free vessel was investigated. Two options remained after analysing different methods of emission free propulsion: battery powered and hydrogen fuel cell powered, both in combination with an electric motor. So in this report, the emission free ferry is an electric vessel. Without additional design changes, a battery powered version is not possible. So a reduction in energy consumption is required. A hydrogen powered ferry is feasible, but more expensive, thus a reduction in energy consumption is desirable as well. It must be mentioned that costs is not the most important aspect, because the reduction in emissions might be worth it. Furthermore, a lot of indirect costs are related to pollution. The effect on energy consumption was analysed for three design related changes: elongating the hull, using carbon composite instead of aluminium, and applying expected future battery and fuel cell systems. Currently, a battery powered ferry is only feasible with an elongated hull, but future technology significantly increases feasibility, also for the original hull length. A reduction of structural weight also increases feasibility, which effectively means a reduction in costs. The hydrogen powered ferry was already feasible, but the above mentioned changes in design improve feasibility, i.e. reduce the costs. Two operational changes were analysed as well: operating at a lower design speed and operating on a shorter crossing. The first has a limited effect on energy consumption, but the latter significantly increases feasibility of the battery powered ferry. Both changes do not have much effect on the feasibility of the hydrogen powered concept. The final concept that was analysed is the hydrofoil supported catamaran, because hydrofoils can significantly reduce resistance. Compared to existing hydrofoil vessels, there are two major differences: the electric concept has relatively more weight, and its design speed is significantly lower. Therefore, the hydrofoil must be relatively large to generate the required lift, and a larger hydrofoil suffers from larger 3D and interference effects. This drastically lowers the efficiency, and as a result, the hydrofoil concept is not a feasible solution. It can be concluded that an emission free fast ferry is feasible. A battery powered ferry is best suited for short crossings and the hydrogen fuel cell powered ferry can operate at longer crossings. The direct costs are likely to be higher, but this might be worth it, as it leads to a reduction of emissions, and thus to a reduction of indirect costs related to pollution. So the remaining question is: do we want to invest now, or pay for the damage afterwards? ... Read more

An issue that arises during the execution of shipbuilding engineering projects at Royal IHC is an imbalance between the sum of all necessary engineering work, and all engineers that are employed who are available to execute the work. This research aims to develop a new method to help establish a proposal engineering work schedule forecast for all engineering work packages in custom trailing suction hopper shipbuilding projects at Royal IHC. To develop the input for the new method, regression analysis on usable historical engineering man-hour data was applied to develop models that quantify work, and curve fitting through the man-hour data was
applied to develop models that determine the timing of work. ... Read more

The design of polar expedition cruise ship is not a trivial task to the naval architect due to the complex nature of the ship itself. Concept exploration are hereby required to improve the understanding of the design problem and identify its challenge as well as possible solutions. However, it is always difficult to generate the technically-feasible design solutions while still satisfying multiple and potentially conflicting performance criteria for the polar expedition cruise ship. There are currently two ways of optimizing the concept design: manual optimization and computer-optimization. The computer-based optimization, such as the Packing Approach developed by TU Delft, can semi-/automatically generate a set of design solutions. After the generation of these design solutions which are unknown in many performance behaviors, it is necessary to post-process them and increase the quality of those designs created from both optimization methods. Design rationale is an effective way to serve as qualitative metrics in post-processing the configuration layouts of the concept designs. However, the ambiguity and potential conflicting aspects within the design rationale are difficult to handle by the current post-processing method while fuzzy logic theory can be utilized to cope with the design problems involving subjective and ambiguity. Hence, it is proposed to develop a new methodology to better post-process the concept design of a polar expedition cruise ship. ... Read more

During the start of a project organisations make estimation on the expected amount of work and the corresponding project duration, the lead time. To make these estimations with a low uncertainty is important because a false estimation could result in cost overruns and project delay. This paper proposes an estimation and planning maturity framework where organisation can asses which methods can be used to ensure the estimation and planning are performed to the lowest possible uncertainty. The framework was implemented at a case study organisation, it was found that selecting the correct estimation and planning methods can result in a lead time estimation with a low uncertainty.  ... Read more