The study explores different system identification techniques that utilize machine learning, including the Restoring Force Surface (RFS) method and Sparse Identification of Nonlinear Dynamics (PySINDy).
These methods have potential to help uncover physical models for soil-pile interaction.
To test these methods , the research first applies them to well-known benchmark systems—simple mechanical models with known nonlinear behaviours. This ensures that the identification techniques work correctly before applying them to real pile-driving experiments.
The experimental data comes from lab-scale vibratory pile-driving tests using strain gauges and accelerometers. The study analyses how forces acting on the pile change over time, focusing on both the tip and shaft resistance. Various mathematical models are tested to see which best captures the nonlinear behaviour.

Due to urbanization, improved living standards and electrification, approximately five times more raw minerals are necessary in 2050 compared to 2018. In deep oceans, the seafloor contains these minerals in the form of polymetallic nodules. Nodules are about the size of golf balls that grow throughout the ocean at depths between 3500 m and 6000 m. They contain a wide variety of metals, such as manganese, copper, nickel, cobalt. Nowadays, for large-scale applications, hydraulic lifting is almost exclusively considered for vertical transportation through the water column. However, there is little research available about using other techniques instead. To tackle this knowledge gap, this thesis studies the feasibility of transporting the nodules using a concept of mechanical lifting. The concept used in this thesis consists of two alternating containers that are lowered and hoisted by lifting and guidance wires. Due to the conditions, such as the large depth, the environmental characteristics and the positioning and heading of the vehicles, there are technical uncertainties regarding mechanical lifting. Risks include the yaw rotation of the container, which might result in rope entanglement and wearing of the ropes. This thesis presents a study into the yawing stability of the concept of mechanical lifting for the vertical transportation of polymetallic nodules, which is a crucial factor to operate reliably.

The research question is answered by performing an experimental test and a CFD analysis. The experimental tests include the dynamics of the system while testing various configurations and is validated by an analytical integration in time and a CFD simulation at model scale. The CFD analysis takes away the uncertainties and unknowns: the drag force, the yawing moment and the fluctuation magnitudes and frequencies. The CFD analysis is performed using the open-source software OpenFOAM and simulates multiple configurations. The results of the simulations are compared to the restoring moment by the guidance wires, by transforming the excitation moments into static and dynamic responses of the system. The CFD model is validated by testing the model with a 2D cylinder and 3D sphere, and by performing a mesh convergence study. The CFD simulations are validated by literature. With the obtained drag forces, the energy consumption is calculated.

From the results, it can be concluded that the system can stably be transported at 2 m/s, as the static and dynamic responses are well within the safety limits. The largest response occurs in the middle of the water column, as the rotational stiffness is the smallest at that location. The dynamic response is smaller compared to the static response, as the high frequent fluctuations (f > 0.075 Hz) are damped. Rope entanglement will not occur during normal operation at 2 m/s. However, critical situations due to incidental events can arise, including a winch failure, friction or a sudden high current. This has not been evaluated in this research and therefore stability cannot be guaranteed. As lowering at 3 m/s with an inclined system and including the current results in a static maximum yawing rotation larger than the safety limit, the stability cannot be guaranteed for operating at 3 m/s.

The rapid development of the wind industry over the past few years has pushed turbine manufacturers to meet the growing energy demands by designing and producing large scale wind turbines.This also means development of larger monopile foundations for the foundation designers in the case of offshore wind turbines.\ Generally, the turbine tower and monopile are modeled together and the loads from the rotor-nacelle assembly are provided by turbine manufacturers.\ The offshore industry is now showing more interest in extracting the loads from the top mass by developing their own tools in order to reduce the dependency on the manufacturers. In order to aid in this process, the present master thesis aims to develop a linear model based on the concept of Dynamic Substructuring which employs a set of equations to compute the interface forces using the kinematics.\ Furthermore, the developed prediction model is used to analyze the loads occurring at the interface between the rotor-nacelle assembly and the tower for different wind speeds and wind conditions.Consequentially, the model was found to produce acceptable loads at higher wind speeds for selected degrees of freedom at the interface while failing to do the same for other degrees of freedom.The results in time domain were converted to the frequency domain to analyse the resonance.The influence of resonance on the interface degrees of freedom was found to be higher at wind speed below the rated condtion.\ These findings can be used as a basis to conduct further investigations into the application of numerical integration concepts to aeroelastic structures.

With the Paris climate accords signed in 2016, most countries have committed themselves to ambitious climate targets during the next decades. One of these targets is a dramatic increase in the overall energy portfolio's market share of renewable energies. This increase in renewable market share will, for a large part, consist of newly built offshore wind farms. In turn, this rise in offshore wind energy projects is expected to be especially dramatic in northern regions, where high and constant wind speeds prevail. However, as offshore wind farm projects move further north, additional challenges need to be faced. One of these is the technical challenge to design offshore wind farms for possible encounters with drifting sea ice. To tackle this challenge, a proper understanding of the mechanics associated with encounters of drifting sea ice with offshore wind turbines is essential.
Such encounters are currently primarily understood phenomenologically, and the associated models simulating these encounters – or ice-structure interactions – therefore are phenomenological as well. Moreover, most ice-structure interaction models are fundamentally one-dimensional, whereas ice-structure interactions are generally not one-dimensional. This mismatch holds especially for ice-structure interactions with offshore wind turbines, where wind loads are generally misaligned with ice loads causing highly two-dimensional ice-structure interaction problems. Therefore, the first half of this work sets out to extend one of the industry-leading phenomenological one-dimensional models – the Hendrikse (2017) model – to a two-dimensional environment. The ultimately developed Zero-friction contact Area variation Model By Omnidirectional Numerical Ice (ZAMBONI) attempts to do so by introducing practical extensions rather than introducing new assumptions. Nevertheless, one extension does entail a shift from current one-dimensional ice-structure interaction models. Namely, the assumption that ice experiences neither friction at the ice-structure interface nor internal shear forces. Consequently, much of the correctness of this model hinges on this extension. To assert the correctness of ZAMBONI. A comprehensive verification campaign is performed as well as a simple order-of-magnitude validation campaign. Although both confirm the extensions' correctness, further validation is required, especially concerning the zero-friction principle. Upon developing and discussing this two-dimensional ice-structure interaction model, the second half of this work couples ZAMBONI to an offshore wind turbine model to gain further insight into ice-structure interactions. These dynamically coupled two-dimensional simulations serve two purposes. Firstly, to compare one- and two-dimensionally simulated load cases of aligned ice and wind. Secondly, to perform newly simulable load cases of misaligned ice and wind. Four primary findings are discussed. Firstly, as hypothesized, introducing a disturbing wind load lowers the ice-structure contact area, causing smaller loads and displacements due to ice loads. This effect is especially well observable for misaligned wind loads and low far-field ice velocities. Secondly, a new ice-structure interaction regime is observed where ice and structure synchronize in the structure's first bending mode. This synchronization occurs most dominantly for two-dimensional ice. Thirdly, frequency lock-in occurs solely in the second bending mode and is terminated at lower ice indentation speeds for two-dimensional than for one-dimensional ice. Finally, small ice-wind misalignments, which are most common, appear highly similar to load cases of fully aligned ice and wind.

Deep sea minerals can offer an additional resource to meet the increasing mineral demands, instigated by population growth and technological advancements. Deep sea minerals exist in different forms at the bottom of the ocean. In this research, polymetallic or manganese nodules are the kind that are of interest. The nodules are 1 to 12 cm large and contain a variety of minerals like copper, nickel and cobalt, but owe their name to its main component manganese. The region with the highest approximated resource of polymetallic nodules is the Clarion-Clipperton Zone (CCZ), situated in the Pacific Ocean between Hawaii and Mexico. The CCZ has water depth reaching 6000 meters, which is a significantly larger working depth than state-of-the-art deep sea projects within the offshore industry. These depths are accompanied by challenging environmental conditions exerted on the deep sea mining system. A deep sea mining system typically consists out of three components: 1) Production Support Vessel (PSV), 2) Vertical Transport System (VTS) and 3) Seafloor Production Tool (SPT). The SPT harvests the nodules from the seabed, the VTS transports the mined nodules through the water column to the surface where they are transferred to the PSV. The focus in this thesis will be on the Vertical Transport System. Where most deep-sea mining developments are considering hydraulic vertical transport with a riser, Boskalis introduces a concept that utilizes mechanical lifting for the vertical transport. This allows for energy efficient transport, relative simplicity of concept and a maximization of the amount of power units above water. The objective of this thesis is captured in the following research question: What is the behaviour of the combined mining system (ropes, skip and SPT) during vertical transportation by means of mechanical lifting? To answer this question, a wide overview is given of the deep-sea minerals that exist on the seafloor and the existing technologies to harvest them. Whilst the system is in principle relatively simple (just two containers (skips) that are alternatingly filled, hoisted to the surface, emptied and lowered again) many challenges arise. To identify these challenges, the system and the production cycle are discussed in detail. Literature research has been done to ensure realistic modelling of characteristics like structural damping of the rope, drag forces and added mass. The safe working load of steel wires is mostly consumed by its self-weight at a length of 4000 meters, making them unsuitable for deep-sea mining. Instead, the less common but naturally buoyant synthetic fibre rope is envisioned. Many of the challenges in this deep-sea mining system originate from the environment as the system is subject to wave action and currents. Therefore, the current profile and wave spectrum typical for the Clarion-Clipperton Zone are obtained to serve as input for further investigation in the hydrodynamic analysis software Orcaflex. The system will be deployed over the entire 6000 m water column, causing the current but also the forward velocity of the system to possibly lead to high drag forces. A reduction of the forward velocity by introducing a new harvesting method is implemented, resulting in a large reduction of the drag forces and offset. The system consists of at least eight ropes, with two moving skips. Combined with the current and vessel motion, rope entanglement is a risk. A solution to prevent the rope entanglement is presented in this thesis. Possible occurrence of vortex-induced-vibrations (VIV) is identified and future research is recommended. The offset analysis shows that a large offset (500m) between the PSV and SPT results in relatively low horizontal forces on the harvester. The system is connected to the PSV, which is subjected to the Pierson-Moskowitz wave spectrum environment it is situated in, resulting in vessel motions. These motions will govern the dynamic behaviour of the system. The skips with attached fibre ropes have different eigenfrequencies on different water depths, as a longer rope will make for a softer system. This causes both skips, full and empty, to resonate in some regions. Consequently, the dynamic tension in the ropes is higher than the static tension, although it does not come forward as problematic. However, undesired slack rope conditions can occur when lowering the empty skip. To conclude, an analysis of the deep-sea mining system has been done in which the eventual design has been modelled to the best extent currently possible. This research underlines the technical feasibility of this deep-sea mining concept. This research also evaluates the questions that have not been answered yet and recommends a variety of interesting topics for future research.

The BAM Tidal Bridge is a proposed bifunctional concept of a bridge connection between two Indonesian islands, and the world’s largest tidal power plant. The wave forcing on the floating structure leads to an undesired dynamic response and a decreased operating reliability. The thesis objective is about designing an additional structure or a design modification to the Tidal Bridge that reduces the downtime to a maximum of five days per year. A model has been developed to analyse the dynamic response of the original Tidal Bridge design, and to test possible design optimisations. Three successive design loops lead to the resulting design of an innovative sway plate structure which fulfils the design objective well.

Oceans account for 71 percent of the earth’s surface, marine resources and energy are abundant. Therefore, making full use of marine energy is a good choice for humans to solve the energy crisis. One way to capture ocean energy is converting wave energy to electrical energy, by means of devices called wave energy converters (WECs). This project introduces a new type of wave energy converter named “Gyroscopic-Pendulum Wave Energy Converter (GP WEC)”. Compared to the classical vertical axis pendulum WEC, a flywheel is added in the system. In combination with the floater motions it creates a gyroscopic effect on the pendulum causing it to rotate, a power take-off device is connected directly to the rotating pendulum shaft in order to harvest the wave energy and generate electrical energy. To investigate whether this new type of WEC will generate more energy than the classical one, this thesis proposes a dry test setup for the gyroscopic pendulum allowing for systematically investigating the gyroscopic effect on its power output. This thesis starts from the design of the GP WEC dry experiment and then provides the clear definition of all the components of equipment, along with the applicable scaling laws of all the components and parameters. Also, the requirements as to limits of the equipment are studied with a parameter study. Using the results of the parameter study a numerical model of the GP WEC is used to simulate the dry-tests. Based on these simulations the range and number of parameters that will be tested in the future experiment are confirmed, and test matrices defined. Some interesting observations from the numerical simulations are further studied looking into the time domain response. This thesis concludes with the definition of a test setup for dry experiments to be executed at TU Delft in a follow-up study, test matrices for investigating the gyroscopic effect on the power output are defined, and simulation results are presented which can be used for later validation of the physical model.

For the offshore market an increase in renewable projects can be observed. The technological innovations are continuously decreasing the costs of renewable projects. Especially offshore wind is getting more cost effective, and is receiving a lot of attention. However, with the growth of the sector, new challenges arise. Water depths are increasing, soil parameters worsening and greater distances from shore need to be overcome. Whereas prices of installation are under pressure. This drives the market towards larger and more innovative installation vessels. A trend can be observed towards monohull craning vessels which combine a large crane with a large storage space on deck. During lifting the monohull vessel experiences large motions of the lifting configuration at even small wave loading. The large motions are mainly the result of resonance within the system, which results in large crane forces. It is these forces which decreases the vessels work-ability. Applying damping to the system is a way to counter the resonance. The tugger winches can be used to apply damping to the lifting configuration. The aim of the thesis is to investigate the potential damping effect of a tugger damping system for the Bokalift 1 during a jacket lifting operation. With special emphasis on the effect of different control systems of the tugger winches. Two different models are used in the thesis to research the effects of tugger damping on the dynamic behavior of the lifting configuration. Namely, a 2D matlab model, and a more extensive 3D Orcaflex model. The Orcaflex model is build for researching the effects of tugger damping and different control systems. Comparing the responses of the model to airy waves loading. To have control in both longitudinal and transverse direction boom winches on the crane are used, in combination with deck winches. Which are located on both ends of the deck. The hydro static properties of the model are calculated with the program GHs. The hydro dynamic properties are calculated with the help of AQWA. The matlab model is used to enable quick research on the effects of tugger damping and different control systems. The model is based on a 5 degree of freedom (DOF) mass-spring-damper-system. The equations of motion (EOM) are derived using the lagrange formalism with help of the program Maplesoft. The model is validated with help of proven software Orcaflex. Seven different control systems are made and tested in the matlab model. The control systems are examined in two different simulations. Firstly the roll motion is studied when the model is subjected to wave loading. Secondly the damping capabilities for the lifting configuration with initial displacement are tested. The first analysis shows the PID controller has the highest roll motion reduction of the jacket. Linear control system scores higher than quadratic. The results from the second analysis shows that stepwise controller takes the shortest to fully damp the lifting configuration. Following on the results of the 2D model analysis the 3D model will further inspect the effect of tugger winches for the linear, quadratic, and PID controller. A model analysis shows there are 4 important modes within the wave excitation range. The combination of these modes results in the highest crane forces at a wave period of 5.5s. The linear and quadratic control system are once again compared, only now in the 3d model. The assessment shows the linear model as more efficient in reducing the crane tip forces. Lastly the linear and PID control systems are compared towards each other and a model without tugger damping. Based on the results, the linear control system increases the total forces on the crane. Where as the PID reduces all forces. It is shown that tugger damping does not necessarily decrease forces acting on the crane tip for head on waves. From the tested control system the PID controller reduces the forces most effectively and efficiently. However the effect of the PID controller depends on the loading wave frequency and for which it is tuned.

The oceans, which cover nearly 70% of the earth’s surface, can be considered as an inexhaustible energy source for renewable electricity due to its size and predictability. One way to capture ocean energy is by harnessing the energy produced by waves at sea, by means of devices called wave energy converters (WECs).

Delft University of Technology is developing a new floating WEC concept called the ”gyroscopic-pendulum”. This concept is a modification of the so called ”classical vertical axis pendulum”, which is capable of producing mechanical power harvested from the rotations of the pendulum around the vertical axis.

The new concept is proposed by adding a flywheel with the aim to enhance the rotations of the pendulum about the vertical axis. The enhancement comes from gyroscopic precession which is created due to a change in the angular moment of the spinning flywheel caused by the torque originating from the weight of the pendulum.

This thesis starts with a general introduction about wave power followed by the mathematical and numerical model of the gyroscopic-pendulum. Numerical simulations are performed in which the gyroscopic-pendulum and the classical pendulum are both imposed with the same harmonic roll motion, while the gyroscopic-pendulum system also receives some power input to rotate the disk. The main objective is to find out in which ranges of amplitude and frequency of imposed motions, the gyroscopic-pendulum results in an improvement of the power efficiency compared to the classical vertical axis pendulum.

The results obtained from tests performed in the simulated conditions, shows us that the gyroscopic-pendulum has a significantly higher efficiency compared to the classical vertical axis pendulum when the frequency of the imposed roll motion is in the range of 1.4 to 1.75 rad/s and the amplitude is in the range of 0.6 to 0.95 푚.

Deep-sea mining is becoming more popular. The Atlantis II Deep is a deep sea mining field of metalliferous muds in the Red Sea. This field could be exploited by transporting the sediments through a pipeline laid from shore onto the sea bed to the field. From determined concentrations with their shear stress-shear rate relation, parameters for the power law and Bingham plastic model were determined, relayed to test data, so that in the end the Bingham Plastic model was used to calculate pwoer consumption for a variety of cases.

The offshore wind industry has been extended over the last years in areas of active seismicity, such as East Asia, where the design of offshore wind turbines becomes significantly challenging, because albeit aerodynamic and hydrodynamic loads mainly act on the offshore structures, earthquake could emerge as a potentially enormous threat. The demand for reliable and economical design of offshore wind turbine foundations has driven the research for analysis of the structural behaviour under the combined action of loads and the study of the parameters that could influence it. The present master thesis deals with the dynamic analysis of the response of an offshore wind turbine monopile, one of the most common types of foundations, subjected to the application of hydrodynamic and earthquake loads. This study focuses on the understanding of the dynamic properties contributing to the dissipation of energy experienced by the structure. More specifically, the sources of damping leading to reduction of the structural vibration in time are investigated, of which the numerical determination is considerably uncertain, while emphasizing on the hydrodynamic and the soil damping. A numerical approach for the estimation of the hydrodynamic viscous damping is presented based on the calculation of the drag coefficient CD and its dependency on the Reynolds number (Re), the Keulegan-Carpenter number (KC) and the surface roughness (k/D). The drag coefficient, and accordingly the hydrodynamic viscous damping, are derived over the length of the monopile where the waves act, highlighting also the consequences of the changes in diameter and depth. Furthermore, the soil radiation damping due to the seismic waves is studied by including the interaction of the soil with the structure. Particularly, the supporting soil is modelled around the monopile with frequency-dependent springs and dampers to represent the soil stiffness and damping, respectively. The estimation of the soil coefficients is accomplished by integrating in the model of the structure, an advanced soil model developed by Dr. J. De Oliveira Barbosa, which gives the dynamic impedance function for the desired band of frequencies. The analysis of the structural response is executed by examining three load cases for the hydrodynamic and earthquake loads. The overall outcome reveals that a noticeable amount of energy is dissipated because of the presence of the soil radiation damping, drawing also the conclusion that the soil-structure interaction should be considered as frequency-dependent during earthquake. Despite the fact that the approach for the estimation of the hydrodynamic viscous damping constitutes a more precise method, its participation in the specific tested cases is limited to the total amount of damping.

In order for the offshore wind industry to be competitive, the cost has to be driven down. One of the major factors that contribute to the overall cost is the over-dimensioning of the substructure. The response of the structure under various loading conditions can provide valuable insight in the design phase so as to provide a structural design that is cost effective yet reliable, and can withstand the loads that are considered to act on the structure.

The objective of the present thesis is the development of a 1D finite element model, that allows for a dynamic analysis of an offshore wind turbine under the combined actions of wind and wave or wind and ice. For this purpose, different models have been combined and improved or extended. Through this model the importance of accounting for non-linear and breaking waves, the effect of the kinematic stretching on the response and the manner in which the misalignment of the load affects the response can be investigated.

A detailed design of the NREL-5MW offshore wind turbine supported by a monopile is subjected to wind, wave and ice action. The aerodynamic action is evaluated through a model valid for the above rated regime when pitch control is active, using a turbulent wind signal resulting from the Kaimal spectrum. The hydrodynamic action is calculated either with the Morison equation or the MacCamy and Fuchs equation with the use of either linear or nonlinear water particle kinematics. An approach towards the calculation of the load from a breaking wave is considered accounting for the wave skewness and asymmetry during such an event. The ice action is calculated through a model that evaluates the force while in the crushing regime. The soil is represented with linear soil springs.

The structure’s response is investigated for all the loads separately at first. The next step is the combined analysis. Aligned and misaligned cases are considered. Results show that wind load is dominating the response in the aligned and misaligned wind and wave case regardless of the method used to calculate the hydrodynamic load in the case of a small wave height. In the case of a larger wave height, using Stokes theory and the Morison equation, the hydrodynamic load is contributing to the resulting response. Concerning the ice loading, the intermittent crushing and the continuous brittle crushing regimes occur for the turbine. The response to the combined wind and ice action appears to be affected by both loads in all examined cases.

Wave power is a large untapped source of renewable energy. There is a wide variety of wave energy converters and one of them is the Symphony Wave Power device. The aim of this thesis is to find the best generator design for the Symphony. There is some research available on generator designs for wave energy converters but the Symphony is a unique case, so a new research needed to be conducted. Several generator types can be used in the Symphony. Compared to an induction and switched reluctance generator, the iron-cored permanent magnet synchronous generator (PMSG) seems a good choice because it is efficient and reliable. A disadvantage, however, is that, in the case of the Symphony, the iron losses are relatively high at partial loads. An air-cored PMSG does not have this problem since it has no iron losses at all. A drawback of the air-cored PMSG is that it needs more permanent magnetic material, which is expensive. Finally, it was decided to test and compare the iron-cored radial flux PMSG and the air-cored axial flux PMSG on both performance and costs. For both generator types, an analytical model was built which puts out the efficiency and material cost. To find the best generator geometries for the case of the Symphony, an optimization procedure was created which minimizes both material costs and losses. It was found that an axial flux air-cored PMSG is both cheaper and more efficient than a radial flux iron-cored PMSG. The iron losses of an iron-cored generator are relatively high at partial loads while the Symphony operates at partial loads most of the time.

With a rapidly growing population and subsequent technological developments, an increase in demand of rare-earth metals evolves. Land-based deposits seem to be insufficient and shortage impends within the coming decades. Mineral resources from the deep ocean are considered as a possible complement. These minerals occur in various forms. One of these forms is lying on the subsea sediment of the deep ocean; polymetallic nodules. The nodules can be best described as potato shaped objects containing amounts of rare earth minerals like copper, nickel and cobalt. The economic feasibility depends on nodule abundance per square meter. An exploitation region with high prospectiveness in terms of economic feasibility is the Clarion-Clipperton Zone, a region in the centre of the Pacific Ocean. As deep-sea mining implies, the mining site is located at a water depth of approximately 4000m. Characteristics such as these automatically result into challenging conditions. Exploitation of the nodules includes subsea harvesting and vertical transportation towards the sea surface. Activities which are within the scope of Boskalis, appealing their know-how and experience in dredging and marine operations. Currently, most developments are focused on vertical transport by means of hydraulic lifting through a riser. In order to avoid challenges such as flow assurance, riser handling and efficiency, Boskalis proposes an alternative solution; mechanical lifting.

Mechanical lifting can be considered as a newcomer in the relative early field of deep-sea mining. However, experience can be gathered from successive deep-sea lowering operations in the oil and gas industry. The objective of this thesis is to investigate the static configuration and dynamic response of the proposed mining system during operation, identify potential showstoppers and in the end asses whether deep-sea mining by mechanical lifting is technical feasible. When simplified, it is merely a matter of collection of nodules in transportation skips and hoisting of these skips towards the sea surface. Nevertheless, within this simple procedure various challenges arise. Therefore a start is made with a proper description of the proposed production method and identification of potential hazards and showstoppers. In complementing the initial research, the project site has been studied in terms of sea floor characteristics and metocean data. These obtained results served as input in further analysis. For example a sheared current is present, influencing the geometry of the hoisting wires. The sheared current phenomenom has been studied in which a quasi-static analysis is performed. The analysis has been carried out by discretization of the hoisting wires in a number of elements with a payload attached at the tip acting as a sinker. Here it became clear that for the applied hoisting setup, the influence of the local current is minimal and the influence of a forward vessel motion significant.

When acting in an offshore environment, the vessel motions might affect the deep-sea mining operation as a result of the connection with the nodule collector. Preliminary to a dynamic analysis, typical vessel motions are determined. This is done by selection of an appropriate mining vessel and implementation of a characteristic sea state using a Pierson-Moskowitz spectrum. Vessel motions are calculated with the software package Seaway, resulting in an output in the frequency domain. The suspended hoisting wires are still numerically modelled by a discretization method. Axial analysis for the applied hoisting setup shows significant magnification of the response of the attached payload at full depth (4000m). This hurdle should be overcome by applying heave compensation, which has become a commonplace in this type of marine operations. Transversal motions for the applied setup are expected to be minimal as a result of the submerged state.

Conclusively, within this research first insight in technical feasibility is gained, but as a matter of fact yield further valuable questions along the lines of deep-sea technology. Therefore, we can conclude that deep-sea mining by means of mechanical lifting is feasible, but still offers numerous interesting topics in future research exceeding the current standards.