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Offshore wind energy is a key enabler of the global net-zero transition. As nearshore fixed-bottom projects reach maturity, floating offshore wind turbines (FOWTs) are becoming the next major focus for large scale deployment. To accelerate this development and reduce construction costs, it is essential to optimize mooring systems through a systematic and performance driven framework. This study focuses on the mooring assessment of the Taiwan-developed DeltaFloat semi-submersible platform supporting a 15 MW turbine at a 70 m water depth offshore Hsinchu, Taiwan. A full-chain catenary mooring system was designed based on site specific metocean conditions. The proposed framework integrates ANSYS AQWA (version 2024 R1) and Orcina OrcaFlex (version 11.5) simulations with sensitivity analyses and performance-based fitness metrics including offset, inclination, and line tension to identify key parameters governing mooring behavior. Additionally, an analysis of variance (ANOVA) was conducted to quantitatively evaluate the statistical significance of each design parameter. Results indicate that mooring line length is the most influential factor affecting system performance, followed by line angle and diameter. Optimizing these parameters significantly improves platform stability and reduces tension loads without excessive material use. Building on the optimized symmetric configuration, an asymmetric mooring concept with unequal line lengths is proposed. The asymmetric layout achieves performance comparable to traditional 3 × 1 and 3 × 2 systems under extreme environmental conditions while demonstrating potential reductions in material use and overall cost. Nevertheless, the unbalanced load distribution highlights the need for multi-scenario validation and fatigue assessment to ensure long-term reliability. Overall, the study establishes a comprehensive and sensitivity-based evaluation framework for floating wind mooring systems. The findings provide a balanced and practical reference for the cost-efficient design of floating offshore wind farms in the Taiwan Strait and other shallow-water regions.

In the presence of dynamic uncertainties, external time-varying disturbances, and limited inputs to the multi-point mooring system (MPMS) of a floating offshore platform (FOP), this paper proposes a robust adaptive dynamic surface (RADS) control method incorporating a disturbance observer. A disturbance observer is designed to estimate the unknown time-varying disturbance and apply feedforward compensation to the control variable. Simultaneously, the adaptive law of the σ-corrected leakage term is employed to estimate the bound of the disturbance observation error, thereby enhancing positioning accuracy. An auxiliary dynamic system (ADS) is then introduced to address input constraints, while the differential explosion problem associated with the traditional inversion method is resolved through the integration of the dynamic surface control (DSC) algorithm. The Lyapunov function is utilized to demonstrate that the controller ensures the consistent ultimate boundedness of all signals within the closed-loop system. Finally, a simulation experiment was conducted based on the eight-point mooring platform of the “Kantan3”, and the positioning accuracy reached 3%, which is higher than the specification requirements of the classification society. The results indicate that the designed controller achieves higher positioning accuracy and improved anti-interference performance and has been put into practical application on “Kantan3”.

Compared with the traditional mooring system, the automated vacuum mooring system can meet the development needs of large-scale ship automation, port automation, and environmental protection. This review describes the latest research focuses, progress, applications, and future perspectives regarding the automated vacuum mooring system. First, the components, working principles, advantages, limits, and risks of the automated vacuum mooring system are discussed. Secondly, typical application cases of automated vacuum mooring systems are introduced, looking at two aspects of the ship-based system and shore-based system. Then, the routine maintenance of the automated vacuum mooring system is introduced. Finally, a discussion on the challenges and future perspectives of the automated vacuum mooring system is provided in this review. The advantages of an automated vacuum mooring system make it a potentially highly effective and economical option for a wider range of ship mooring than a traditional mooring system.

This paper proposes a novel integrated foundation structure of floating wind turbine and net cage by combining large capacity semi-submersible wind turbines with aquaculture cages. The research mainly focuses on the effect of biological fouling on net cage structures and safety performance of mooring systems. The study firstly validates the simplified model of net cage through comparing with results of existing scaled experimental models. Then, a hydrodynamic analysis is conducted on the net cage model to obtain the RAOs of motion response of the structure under frequency-domain analysis, and damping correction is also carried out on the structure. Finally, time-domain analyses under irregular wave conditions are conducted to evaluate the effects of biofouling fouling on motion responses of net cage foundation and tensions of mooring lines.

Deep-sea wave-energy-integrated aquaculture platforms (WEAPs) lack systematic design guidance, facing inherent trade-offs between structural safety, aquaculture stability, and wave energy harvesting. This study optimizes a 300 m-class WEAP under 10-year return-period typhoon wave conditions (JONSWAP spectrum) via numerical comparisons of rigid/buoy-sinker mooring systems and single/dual-WEC-pontoon schemes. Results show that the proposed eight-chain buoy-sinker mooring reduces the WEAP’s horizontal displacement by 92.4% and peak mooring tension by 27% compared with rigid mooring. For the dual-WEC-pontoon configuration, this mooring further enhances motion stability and boosts wave energy conversion efficiency to 38–42%. With excellent hydrostatic stability and a 7440.3 m³ stable aquaculture volume, the dual-WEC-pontoon WEAP with eight-chain buoy-sinker mooring serves as an optimal, scalable solution for 300 m deep-sea operations.

High-fidelity viscous computational fluid dynamics (CFD) models coupled to dynamic mooring models is becoming an established tool for marine wave-body-mooring (WBM) interaction problems. The CFD and the mooring solvers most often communicate by exchanging positions and mooring forces at the mooring fairleads. Mooring components such as submerged buoys and clump weights are usually not resolved in the CFD model, but are treated as Morison-type bodies. This paper presents two recent developments in high-fidelity WBM modelling: (i)  a one-way fluid-mooring coupling that samples the CFD fluid kinematics to approximate drag and inertia forces in the mooring model; and (ii) support for inter-moored multibody simulations that can resolve fluid dynamics on a mooring component level. The developments are made in the high-order discontinuous Galerkin mooring solver MoodyCore, and in the two-phase incompressible Navier–Stokes finite volume solver OpenFOAM. The fluid-mooring coupling is verified with experimental tests of a mooring cable in steady current. It is also used to model the response of the slack-moored DeepCwind FOWT exposed to regular waves. Minor effects of fluid-mooring coupling were noted, as expected since this a mild wave case. The inter-mooring development is demonstrated on a point-absorbing WEC moored with a hybrid mooring system, fully resolved in CFD-MoodyCore. The WEC (including a quasi-linear PTO) and the submerged buoys are resolved in CFD, while the mooring dynamics include inter-mooring effects and the one-way sampling of the flow. The combined wave-body-mooring model is judged to be very complete and to cover most of the relevant effects for marine WBM problems.

Floating offshore wind (FOW) requires cost reduction to compete with fixed offshore wind, and other traditional and renewable energy sources. One major cost contributor in FOW is the mooring system. Volume effects are expected to deliver significant savings for most cost drivers, but moorings are already produced at scale and at volume for the oil and gas sector, and innovation is required to address the specific challenges of FOW. This paper investigates the use of Dublin Offshore’s load reduction device (LRD) integrated with high-modulus synthetic mooring lines in an inclined taut mooring (ITM) configuration for semi-submersible station keeping. The ITM comprises a 3-line array with vertically loaded anchors within a reduced mooring footprint, fully synthetic Dyneema® DM20 mooring lines, and optimized system compliance provided through an in-line LRD on each mooring line. The ITM allows mooring designers to significantly reduce component count, risk of failure, CAPEX, and lifetime cost of the mooring system. Wave tank testing was carried out at 1:60 scale using a variant of the TetraSub, a market-ready 15 MW semi-submersible FOW platform, developed by Stiesdal Offshore Technologies (SOT) at the Offshore Basin in MARIN in Q3 2021. The experimental results of wave tank testing presented in this paper demonstrate the feasibility of the innovative ITM mooring configuration. In addition, good agreement is observed between LRD quasi-static performance and each of the numerical analysis in OrcaFlex, and the wave tank testing results.

As the development of floating offshore wind turbines (FOWTs) progresses from offshore to deeper sea, the demands on mooring systems to ensure the safety of the structure have become increasingly stringent, leading to a concomitant rise in costs. A parameter optimization method for the mooring system of FOWTs is proposed, with the mooring line length and anchor radial spacing as the optimization variables, and the minimization of surge, yaw, and nacelle acceleration as the objectives. A series of mooring system configuration samples are generated by the fully analytical factorial design method, and the open source program OpenFAST is employed to simulate the global responses in the time domain. To enhance the efficiency of the optimization process, a multi-objective evolutionary algorithm, Non-dominated Sorting Genetic Algorithm II (NSGA-II), is utilized to find the Pareto-optimal solutions, alongside a Kriging model, which serves as a surrogate model for the FOWTs. This approach was applied to an IEC 15MW FOWT to demonstrate the optimization procedure. The results indicate that the integration of the genetic algorithm and the surrogate model achieved rapid convergence and high accuracy. Through this optimization process, the longitudinal motion response of FOWTs is reduced by a maximum of 6.46%, the yaw motion by 2.87%, and the nacelle acceleration by 11.55%.

Suction piles have increasingly been considered as foundations for offshore facilities. In this study, the pullout behaviors of suction piles embedded in saturated sand subjected to combined vertical and horizontal loading at various inclination angles and pad-eye positions are investigated carrying out centrifugal tests and finite element (FE) analyses. The ultimate pullout capacities obtained from the model tests and FE analyses both increased as the inclination angle was close to 0° and the pad-eye position approached 75% of the pile length from the lid. This is associated with the increase of the passive earth pressure and friction between the soil and suction pile while the pile is pulled out. The failure envelopes were suggested depending on pad-eye positions to improve the design approach for offshore foundations. The optimal pad-eye positions for catenary and taut-leg mooring systems were then investigated by additional FE analyses to demonstrate the practical implications. For both mooring systems, the largest ultimate pullout capacity was obtained when the pad-eye was located at 75% of the suction pile length below the lid. The ultimate pullout capacity of the catenary mooring system was determined to be 1.94 times that of the taut-leg mooring system under the same conditions.

This paper presents a multi-module oscillating water column (OWC) wave energy converter (WEC) array system, comprising seven interconnected OWC modules. The modules are connected by elastic ropes with clumped weights positioned at the ropes’ midpoints. Three distinct mooring systems are designed for this OWC array, and the impact of mooring configurations on the hydrodynamic responses of the OWCs and mooring tensions is thoroughly examined. Three-dimensional potential flow theory is applied to perform time domain analyses. The motion responses of representative modules, the tension of specific mooring lines, and the spacing between adjacent modules in the array system are investigated through a comprehensive coupled dynamic analysis in the time domain. Based on these analyses, recommendations are provided for the optimal mooring system configuration for the array system.