Journal of Marine Science and Engineering

36 pages, 1233 KB

Open AccessArticle

Analytical Solution for Dynamic Responses of Distinct Tubular Piles Under Vertical Seismic Excitation Considering Water–Pile–Soil Interaction

by Yiming Huang, Jiaxi Zhou, Xin Li, Yichen Liu and Piguang Wang

J. Mar. Sci. Eng. 2025, 13(11), 2158; https://doi.org/10.3390/jmse13112158 - 14 Nov 2025

Abstract

Offshore tubular pile systems in earthquake-active marine regions face risks from vertical seismic excitation, water dynamics, and pile–soil interactions. Thus, an analytical solution for offshore tubular piles considering multi-physical field coupling (the mutual interactions between seawater, tubular pile, and surrounding soil) is developed [...] Read more.

Offshore tubular pile systems in earthquake-active marine regions face risks from vertical seismic excitation, water dynamics, and pile–soil interactions. Thus, an analytical solution for offshore tubular piles considering multi-physical field coupling (the mutual interactions between seawater, tubular pile, and surrounding soil) is developed to investigate their dynamic responses under vertical seismic loading. Firstly, the dynamic response of the tubular pile system is decomposed into free-field and scattered-field components. The governing equations for water, soil, and tubular piles (one-dimensional and three-dimensional tubular pile models) are established, with the strict enforcement of boundary conditions such as displacement continuity and stress equilibrium. Then, analytical solutions for both one-dimensional and three-dimensional tubular pile models are derived. The proposed framework is validated by comparison with existing literature solutions, confirming its rationality. Subsequently, parametric analyses are conducted to explore the influences of key factors. The results indicate that it is essential to consider the coupled effects of vertical earthquakes and water–pile–soil interaction in the design of offshore tubular piles, as neglecting multi-field coupling or adopting oversimplified models can lead to inaccurate predictions of dynamic responses. Full article

(This article belongs to the Special Issue Wave–Seabed–Structure Interaction (WSSI) Analysis of Coastal and Offshore Structures)

20 pages, 4110 KB

Open AccessArticle

Experimental Investigation of a Novel Single-Shank Drag Anchor Design

by Chuheng Wu, Peng Guo, Youhu Zhang, Xiangyu Wang and Di Lei

J. Mar. Sci. Eng. 2025, 13(11), 2157; https://doi.org/10.3390/jmse13112157 - 14 Nov 2025

Abstract

Drag embedment anchor (DEA) constitutes a compelling anchoring solution for an array of floating structures, attributable to its exceptional efficiency in holding capacity and the comparatively modest expenditures incurred in manufacturing and installation. The holding capacity of DEAs is, to a large extent, [...] Read more.

Drag embedment anchor (DEA) constitutes a compelling anchoring solution for an array of floating structures, attributable to its exceptional efficiency in holding capacity and the comparatively modest expenditures incurred in manufacturing and installation. The holding capacity of DEAs is, to a large extent, dictated by the penetration depth achieved during installation. In hard soils, such as dense sand and stiff clay, the penetration depth of DEAs is often limited due to the large soil resistance acting on the shank structure, which in turn limits its holding capacity. In this paper, a novel anchor design with a single flat shank is proposed, which can greatly reduce the soil resistance on the shank during installation, in the hope of improving the penetration depth and consequently the holding capacity of DEAs. To verify this design assumption, a comprehensive suite of large deformation numerical simulations is carried out in both clayey and sandy soils. In addition, a series of physical model tests are performed in uniform sand. The results from both the numerical simulations and the model tests confirm the superior penetrability and holding capacity of the proposed single-shank anchor design. Full article

(This article belongs to the Special Issue Advances in Marine Geomechanics and Geotechnics)

26 pages, 8163 KB

Open AccessArticle

Fin Whale (Balaenoptera physalus) Migration in the Strait of Gibraltar: Evaluating Maritime Traffic Threats and Conservation Measures

by Rocío Espada, Liliana Olaya-Ponzone, Estefania Martín-Moreno, Paco Gil-Vera, Iris Anfruns Fernández, Daniel Patón Domínguez and José Carlos García-Gómez

J. Mar. Sci. Eng. 2025, 13(11), 2156; https://doi.org/10.3390/jmse13112156 - 14 Nov 2025

Abstract

The Strait of Gibraltar (SG) is a key biogeographic and ecological corridor connecting the Mediterranean Sea and the Atlantic Ocean, enabling the seasonal migrations of fin whales (Balaenoptera physalus). The objective of this study was to characterize, for the first time, [...] Read more.

The Strait of Gibraltar (SG) is a key biogeographic and ecological corridor connecting the Mediterranean Sea and the Atlantic Ocean, enabling the seasonal migrations of fin whales (Balaenoptera physalus). The objective of this study was to characterize, for the first time, the spatial and temporal exposure of the species to maritime traffic during its migration through the SG, quantifying movement patterns, individual composition, and collision risk to identify critical areas for conservation. Validated observations collected between April 2016 and October 2024, with additional records in January and March 2025, were integrated with EMODnet vessel density layers to assess monthly distributions of sightings, individuals, calves, migration patterns, and behavior. A total of 347 sightings comprising 692 individuals were recorded, revealing predominantly westward movements between June and August. Spatial overlap analyses indicated that the highest exposure occurred both near the Bay of Algeciras/Gibraltar and in the northern half of the Central SG, where cargo ship and tanker traffic coincides with dense migration routes and where injuries have been documented in the field. These findings delineate high-risk areas for fin whales throughout the SG and provide an empirical basis for spatial management measures, including speed reduction zones, adaptive route planning, and the possible designation of the area as a cetacean migration corridor. The proposed measures aim to mitigate collision risk and ensure long-term ecological connectivity between the Mediterranean and the Atlantic. Full article

(This article belongs to the Special Issue Combining Field Observations and Satellite Remote Sensing to Monitor Marine Ecosystem Dynamics)

19 pages, 9197 KB

Open AccessArticle

Optimal Design of Single Point Moorings for a Weathervaning Floating Wind Twin-Turbine Platform in Real Bathymetries

by Magnus Daniel Kallinger, Hector del Pozo Gonzalez, José Luis Domínguez-García and Javier Fernandez-Quijano

J. Mar. Sci. Eng. 2025, 13(11), 2155; https://doi.org/10.3390/jmse13112155 - 14 Nov 2025

Abstract

This article presents the design and optimization of the mooring system for a floating wind platform inspired by W2Power, which incorporates two wind turbines on a semi-submersible structure that weathervanes using a single-point mooring (SPM) system. Although several industrial concepts have adopted SPM [...] Read more.

This article presents the design and optimization of the mooring system for a floating wind platform inspired by W2Power, which incorporates two wind turbines on a semi-submersible structure that weathervanes using a single-point mooring (SPM) system. Although several industrial concepts have adopted SPM configurations, research on their performance remains limited. This work addresses that gap by developing and applying a set of optimization strategies for the mooring system of such a platform using OrcaFlex, with the objective of minimizing the capital expenditure while satisfying Ultimate Limit State (ULS) and Fatigue Limit State (FLS) cases. The methodology was tested across two distinct marine environments: the Atlantic (Gran Canaria, GC-1) and the Mediterranean (Catalonia, LEBA-1), both characterized by their irregular bathymetry. In Catalonia, the environmental conditions are almost omnidirectional, while the platform in Gran Canaria is exposed to highly unidirectional loads. The article presents the most cost-effective solution for single-point moorings with three, four, and five lines in each case. Results demonstrate the viability of SPM-based floating wind systems with twin-turbines under diverse site conditions. Full article

(This article belongs to the Special Issue Advanced Studies in Marine Structures)

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32 pages, 4978 KB

Open AccessArticle

A Multivariate AI-Driven Generalized Framework for Structural Load Prediction of Monopile Used for Offshore Wind Turbines Under Non-Linear Wind and Wave Conditions

by Sajid Ali, Muhammad Hassaan Farooq Khan and Daeyong Lee

J. Mar. Sci. Eng. 2025, 13(11), 2154; https://doi.org/10.3390/jmse13112154 - 14 Nov 2025

Abstract

Predicting structural loads on offshore wind turbine support structures under varying environmental conditions is a complex yet critical task, particularly for large-capacity turbines such as the 15 MW offshore wind turbine. Current prediction methods often struggle with accuracy, especially for torsional moments, due [...] Read more.

Predicting structural loads on offshore wind turbine support structures under varying environmental conditions is a complex yet critical task, particularly for large-capacity turbines such as the 15 MW offshore wind turbine. Current prediction methods often struggle with accuracy, especially for torsional moments, due to the non-linear interactions between wind parameters and structural responses. To address this challenge, present study develops a generalized load estimation framework using multivariable polynomial regression, leveraging 10,000 numerical simulations. The framework accounts for four critical variables: Extreme Wind Speed (30 to 40 m/s), Turbulence Intensity (12% to 16%), Flow Inclination Angle (−8° to +8°), and Shear Exponent (0.1 to 0.3). The proposed equations predict six key moment components at the tower base, including the bending moments about the y-axis, torsional moments about the z-axis, bending moments in the x-y, x-z, and y-z planes, and the resultant combined moment. The framework was validated using 2000 testing data points, achieving high accuracy with R² values exceeding 0.92 for all moments. Specifically, the prediction accuracy was highest for the resultant combined moment and y-z bending moment, with average absolute errors of 5.76% and 5.97%, respectively, while x-z bending moment had a slightly higher error of 13.91%, highlighting that torsional moments are inherently more challenging to predict. Heatmap and scatter plot analyses confirmed that the predicted moments align closely with the simulated values, particularly for the torsional moment about the z-axis and y-z bending moment, with standard deviation values as low as 4.85. By optimizing polynomial degrees between 2 and 4, the framework effectively balances prediction accuracy and computational efficiency. This approach provides engineers and scientists with a reliable tool for load estimation, facilitating improved design and analysis of offshore wind turbine support structures. Full article

(This article belongs to the Section Ocean Engineering)

16 pages, 8549 KB

Open AccessArticle

Numerical Simulation and Tests of Lateral Bearing Capacity of Sloped Offshore Monopile Under Vertical Load and Lateral Cyclic Load

by Yongqing Lai, Gen Xiong, Ben He, Yilong Sun, Lin Guo and Kaiyuan Liu

J. Mar. Sci. Eng. 2025, 13(11), 2153; https://doi.org/10.3390/jmse13112153 - 14 Nov 2025

Abstract

Offshore monopile foundations endure complex loads during service. They bear vertical loads from the superstructure’s self-weight and lateral cyclic loads (e.g., wind, waves), while near-coastal seabeds are usually sloped. To resolve these issues, model pile tests under combined vertical and lateral cyclic loads [...] Read more.

Offshore monopile foundations endure complex loads during service. They bear vertical loads from the superstructure’s self-weight and lateral cyclic loads (e.g., wind, waves), while near-coastal seabeds are usually sloped. To resolve these issues, model pile tests under combined vertical and lateral cyclic loads were carried out to study how slope angle and vertical load affect monopile deformation. A numerical model was validated via comparison with test results and then used to reveal the development of cumulative deformation in offshore sloped monopiles under the above combined loads. The results show that, below 1000 cycles, the cumulative displacement of the pile increases logarithmically with the number of cycles. As the slope angle increases, the cumulative deformation increases. In these tests, the cumulative deformation of the pile increases by 114% compared to the results of the flat site, but it decreases with an increase in vertical load. As such, when a 3 N vertical load is applied to the pile top, its deformation at the flat site decreases by 20%, but its deformation at a 20° slope site decreases by 10%. Finally, a predicted formula is proposed for offshore monopiles with the effect of slope angle, and this formula can provide a preliminary assessment method of cumulative. Full article

(This article belongs to the Special Issue Wave Loads on Offshore Structure)

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22 pages, 5170 KB

Open AccessArticle

Bathymetric Changes in the Submerged Delta of the Jucar River (Spain, Western Mediterranean) from the 19th Century to the Present

by Irene Montoya-Blázquez, Ana Rodríguez-Pérez, Borja Martínez-Clavel and Ana María Blázquez

J. Mar. Sci. Eng. 2025, 13(11), 2152; https://doi.org/10.3390/jmse13112152 - 13 Nov 2025

Abstract

The Jucar is a perennial river with a high sedimentary load which has transferred sediment to the continental shelf in the form of a deltaic lobe since pre-historic times. The aim of this study is to analyze the changes that have occurred in [...] Read more.

The Jucar is a perennial river with a high sedimentary load which has transferred sediment to the continental shelf in the form of a deltaic lobe since pre-historic times. The aim of this study is to analyze the changes that have occurred in the submerged delta of the Jucar since the nineteenth century. With this aim in mind, five nautical charts were georeferenced, covering the period from 1893 to the present day, from which Digital Elevation Models were generated and compared using Geographic Information Systems. The results indicate that the large-scale contributions of the nineteenth century caused the submerged delta to grow during the cold, dry period of the Little Ice Age. In the mid-twentieth century, the flow and solid load of the river were reduced by the construction of dams, leading to the stabilization of the delta. The bursting of the Tous Dam in 1982 and the ensuing ordinary floods that occurred until its reconstruction, led to large amounts of sediment that counteracted the anthropic action generated by the sediment trap of the dams. The climate of the twenty-first century, characterized by frequent extreme weather events, has allowed the deltaic lobe to continue to grow until the present day since these events increased sediment input to the shelf. Coastal erosion is also observed. Full article

(This article belongs to the Section Geological Oceanography)

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27 pages, 5183 KB

Open AccessArticle

Vulnerability of Black Sea Mesozooplankton to Anthropogenic and Climate Forcing

by Elena Bisinicu and Luminita Lazar

J. Mar. Sci. Eng. 2025, 13(11), 2151; https://doi.org/10.3390/jmse13112151 - 13 Nov 2025

Abstract

Mesozooplankton are pivotal for Black Sea food webs, yet they are highly vulnerable to hydrographic variability, eutrophication, and human pressures. This study analysed mesozooplankton dynamics along the Romanian coast (2013–2020) across three sectors (north, central, and south) and two distinct periods (cold and [...] Read more.

Mesozooplankton are pivotal for Black Sea food webs, yet they are highly vulnerable to hydrographic variability, eutrophication, and human pressures. This study analysed mesozooplankton dynamics along the Romanian coast (2013–2020) across three sectors (north, central, and south) and two distinct periods (cold and warm seasons), integrating Abundance–Biomass Comparison (ABC) curves with Fuzzy Cognitive Mapping (FCM). Results revealed a clear disturbance gradient: the Danube-influenced north supported high abundances of small-bodied taxa; the central sector maintained the most resilient and functionally diverse assemblages; and the southern sector showed chronic degradation with Noctiluca scintillans dominance. ABC curves quantified disturbance, with curve convergence in the north and near overlap in the south during summer, while FCM highlighted network simplification and reduced functional redundancy. Climate scenario simulations projected further declines in cladocerans and meroplankton under warming and freshening, whereas copepods showed relative resilience. Collectively, the findings demonstrate progressive simplification of mesozooplankton and declining energy transfer efficiency, underscoring the need to integrate zooplankton-based indicators into Black Sea monitoring and management frameworks. Full article

(This article belongs to the Section Marine Biology)

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17 pages, 2676 KB

Open AccessArticle

Observations on the Benthic Heterobranch “Sea Slugs” (Mollusca: Gastropoda) of Lampedusa, the Southernmost Island of Italy (MPA Isole Pelagie)

by Andrea Lombardo and Giuliana Marletta

J. Mar. Sci. Eng. 2025, 13(11), 2150; https://doi.org/10.3390/jmse13112150 - 13 Nov 2025

Abstract

Thanks to their striking shapes and colors, heterobranch “sea slugs” are probably the most sought-after group of marine critters by scuba divers around the world. Nevertheless, for many of the islands and coasts of Sicily, there are no specific studies on the fauna [...] Read more.

Thanks to their striking shapes and colors, heterobranch “sea slugs” are probably the most sought-after group of marine critters by scuba divers around the world. Nevertheless, for many of the islands and coasts of Sicily, there are no specific studies on the fauna of this group (formerly known as opisthobranchs). Even Lampedusa, one of the most famous islands in the Mediterranean, is no exception to this. To fill this knowledge gap, the authors conducted a faunal study dedicated to this group in July 2025. Data collection, carried out using the photographic-capture technique both during scuba diving and snorkeling, led to the finding of 22 species of heterobranch “sea slugs”. A comparison of the heterobranch “sea slugs” of Lampedusa with that of other Sicilian islands revealed a low diversity of these mollusks on this island. This scarcity of fauna is probably due to the lack of favorable environments and the considerable environmental homogeneity that characterizes the seabed and coastal areas of Lampedusa. Nevertheless, the discovery of some species of considerable biogeographical importance, together with the island’s unique geographical position, make it an important location to monitor for the study of the distribution patterns of allochthonous marine Heterobranchia species that enter into the Mediterranean Sea. Full article

(This article belongs to the Section Marine Biology)

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37 pages, 5024 KB

Open AccessArticle

Optimal Ship Pipe Route Design: A MOA*-Based Software Approach

by Zongran Dong, Kai Li, Heng Chen and Chenghao Sun

J. Mar. Sci. Eng. 2025, 13(11), 2149; https://doi.org/10.3390/jmse13112149 - 13 Nov 2025

Abstract

For the ship pipe routing design (SPRD) problem, previous studies have mainly employed bio-inspired algorithms such as multi-objective ant colony optimization (MOACO), non-dominated sorting genetic algorithm II (NSGA-II), and multi-objective particle swarm optimization (MOPSO). This paper proposes a novel approach based on the [...] Read more.

For the ship pipe routing design (SPRD) problem, previous studies have mainly employed bio-inspired algorithms such as multi-objective ant colony optimization (MOACO), non-dominated sorting genetic algorithm II (NSGA-II), and multi-objective particle swarm optimization (MOPSO). This paper proposes a novel approach based on the multi-objective A* (MOA*) algorithm to solve the SPRD. First, the optimization objectives and constraints of the SPRD problem are defined, and then an MOA*-based routing framework is developed. The time and space complexities of the approach are analyzed, and key components such as the cost functions, the solution dominance relationship, dynamic probability-based pruning, and neighbor node exploration strategy are designed to enhance solution diversity and search efficiency. Additionally, a space cascade expansion method is proposed to improve the computational efficiency of the MOA* in large-scale grid spaces. Comparative studies with MOACO, NSGA-II, GA-A*, and gray wolf optimization (GWO) on simulated cases of varying complexities and practical piping scenarios demonstrate the effectiveness of the MOA*. Furthermore, the applicability of the MOA* is validated against practical piping requirements, including the rapid generation of sub-optimal solutions, non-orthogonal routing, and partitioned pipe layouts. Experimental results, supported by a C++/OpenGL-based prototype software, show that the MOA* requires no extensive parameter tuning, exhibits stable computational efficiency and optimization capability, and demonstrates competitive performance in Pareto-optimal diversity compared with other algorithms. Full article

(This article belongs to the Section Ocean Engineering)

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23 pages, 2676 KB

Open AccessArticle

Influence of Human Activity on Wet Deposition and Nitrogen Species in Coastal and Marine Environments

by Hung-Yu Chen, Jia-Han Lin and FuJung Tsai

J. Mar. Sci. Eng. 2025, 13(11), 2148; https://doi.org/10.3390/jmse13112148 - 13 Nov 2025

Abstract

In this study, 101 and 102 rainwater samples were collected from April 2020 to February 2024 in a coastal and marine area, respectively. The results show that the Cl/Na ratios in both study areas were lower than the seawater value (1.17), suggesting chloride [...] Read more.

In this study, 101 and 102 rainwater samples were collected from April 2020 to February 2024 in a coastal and marine area, respectively. The results show that the Cl/Na ratios in both study areas were lower than the seawater value (1.17), suggesting chloride depletion. The chloride depletion rates in both areas decreased after the COVID-19 lockdown period. The molar ratio of NH₄⁺ to non-sea-salt sulfate (nss-SO₄²⁻) was 1.54, with a mixture of (NH₄)₂SO₄ and NH₄HSO₄ in the coastal area, and 0.83, with NH₄HSO₄ as the main form, in the marine area. A decreasing trend attributed to high O₃ and relative humidity (RH) levels occurred in 2022. Among the dissolved organic nitrogen (DON) species, DON accounted for 24% and 32% of the total dissolved nitrogen (TDN) in the coastal and marine areas, respectively, indicating a greater relative contribution under lower anthropogenic influence. On the basis of the correlation between the species and source analysis results, NO₃⁻ mainly originated from fossil fuel combustion, NH₄⁺ originated from agricultural emissions and secondary aerosols, and DON originated from secondary aerosols via combustion processes and natural emissions. In terms of the flux, due to lockdown activities, the Dissolved Inorganic Nitrogen (DIN) flux decreased significantly from 40.6 to 19.3 mmol m⁻² yr⁻¹ in the coastal area and from 27.7 to 15.1 mmol m⁻² yr⁻¹ in the marine area. Additionally, a slight decrease occurred in the DON flux, from 21.6 to 19.3 mmol m⁻² yr⁻¹ and from 27.7 to 15.1 mmol m⁻² yr⁻¹, respectively. Regarding new production, based on nitrogen input, the level in the coastal area decreased from 5.83 to 2.10 g C m⁻² yr⁻¹, and that in the marine area decreased from 3.92 to 1.55 g C m⁻² yr⁻¹, indicating a significant reduction during the COVID-19 lockdown. Full article

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22 pages, 5659 KB

Open AccessArticle

Lateral Instability of Submarine Pipelines on Sloping Silt Seabeds: Experimental Investigation and an Improved Predictive Model

by Dang Zhao, Yang He, Yumin Shi, Ning Wang, Jun Liu and Ying Zhang

J. Mar. Sci. Eng. 2025, 13(11), 2147; https://doi.org/10.3390/jmse13112147 - 13 Nov 2025

Abstract

Lateral pipe-soil interaction is crucial for the on-bottom stability design of submarine pipelines, particularly on deep-water sloping silt seabeds. To address this, a mechanical-actuator facility has been specially designed and utilized to simulate the lateral instability process of a pipe on silt slopes [...] Read more.

Lateral pipe-soil interaction is crucial for the on-bottom stability design of submarine pipelines, particularly on deep-water sloping silt seabeds. To address this, a mechanical-actuator facility has been specially designed and utilized to simulate the lateral instability process of a pipe on silt slopes (α) ranging from −15° to +15°. In this study, variations in the dimensionless submerged pipeline weight (G = 0.607–1.577) and initial embedment ratios (|e₀|/D = 0.01–0.50) are also considered. Experimental results reveal several key findings. First, brittle pipe-soil responses are observed: under embedment ratios larger than 0.05, the breakout soil resistance is dominated by suction due to negative pore pressure generation at the rear of the pipe, whereas under lower embedment ratios, it is primarily governed by interface friction and cohesion. Second, for a constant submerged pipeline weight (G = 1.092), the breakout drag force increases linearly with slope angle, whereas the breakout soil resistance decreases linearly—a difference attributed to the gravitational component W_ssinα. Specifically, compared to a horizontal flat seabed, the breakout lateral drag force increases by approximately 33% for upslope instability (α = +15°), but decreases by about 24% for downslope instability (α = −15°). Third, the dimensionless lateral-soil-resistance coefficient on silt increases nonlinearly and monotonically with the slope angle, a trend opposite to that reported for sandy seabeds. Finally, an improved model is proposed that explicitly incorporates silt slope angle, submerged pipeline weight, and embedment ratio. This study aims to offer valuable insights into the stability of pipelines on partially drained continental silt slopes and to support the adoption of slope-specific criteria in future engineering designs. Full article

(This article belongs to the Special Issue Wave–Seabed–Structure Interaction (WSSI) Analysis of Coastal and Offshore Structures)

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24 pages, 1819 KB

Open AccessArticle

Physics-Driven Collision Risk Evaluation of Autonomous Surface Vehicles Using Quaternion Ship Domain and Geometric-Temporal Indicators

by Zongkai Wang, Wenyan Huang and Namkyun Im

J. Mar. Sci. Eng. 2025, 13(11), 2146; https://doi.org/10.3390/jmse13112146 - 13 Nov 2025

Abstract

With the rapid advancement of artificial intelligence and computational technologies, collision risk assessment remains a key challenge for Autonomous Surface Vehicles (ASVs). Traditional approaches typically based on five indicators including distance, Distance/Time to Closest Point of Approach (DCPA/TCPA), relative heading, and speed ratio [...] Read more.

With the rapid advancement of artificial intelligence and computational technologies, collision risk assessment remains a key challenge for Autonomous Surface Vehicles (ASVs). Traditional approaches typically based on five indicators including distance, Distance/Time to Closest Point of Approach (DCPA/TCPA), relative heading, and speed ratio often suffer from redundancy, weak indicator independence, and limited correspondence to the physical characteristics of dynamic encounters. To overcome these limitations, this study proposes a physics-driven collision risk evaluation framework grounded in the Quaternion Ship Domain (QSD). The model simplifies the indicator system to three physically interpretable metrics: inter-ship distance, the coupled DCPA-TCPA index, and the coupled Bow Crossing Range-Bow Crossing Time (BCR-BCT) index. A logarithmic and sigmoid function is introduced as the factor collision risk normalization function, in contrast to a traditional Min–Max scaling function, thereby enhancing the smoothness and interpretability of risk evolution. Python-based simulations involving overtaking, head-on, and crossing scenarios were conducted to validate the proposed approach. The results demonstrate that the framework accurately captures both the magnitude and temporal evolution of collision risk, significantly improving interpretability, robustness, and practical applicability. The proposed QSD-based model provides a physics-consistent and computationally efficient solution for real-time collision risk assessment of ASVs. Full article

(This article belongs to the Section Ocean Engineering)

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2 pages, 492 KB

Open AccessCorrection

Correction: Wan et al. A TransUNet-Based Intelligent Method for Identifying Internal Solitary Waves in the South China Sea. J. Mar. Sci. Eng. 2025, 13, 1154

by Zubiao Wan, Yuhang Zhu, Shiqiu Peng, Jieshuo Xie, Shaotian Li and Tao Song

J. Mar. Sci. Eng. 2025, 13(11), 2145; https://doi.org/10.3390/jmse13112145 - 13 Nov 2025

Abstract

In the original publication [...] Full article

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18 pages, 4469 KB

Open AccessArticle

Influence Mechanism of Well Location and Near-Well Secondary Hydrates on Gas Production of Class 1S Hydrate Reservoirs

by Xian Li, Chenlu Xu, Hongfeng Lu, Zihao Zhao, Jiawang Chen, Liwen Nan, Lu Yu, Jinwen Du, Changwen Xiao, Bo Liu and Zhejun Pan

J. Mar. Sci. Eng. 2025, 13(11), 2144; https://doi.org/10.3390/jmse13112144 - 12 Nov 2025

Abstract

In recent years, a new type of natural gas hydrate reservoir (designated as Class 1S reservoir) has been discovered in the Qiongdongnan Basin. Within this hydrate reservoir, free gas and hydrate coexist within the same stratum. The Class 1S reservoir is comprised of [...] Read more.

In recent years, a new type of natural gas hydrate reservoir (designated as Class 1S reservoir) has been discovered in the Qiongdongnan Basin. Within this hydrate reservoir, free gas and hydrate coexist within the same stratum. The Class 1S reservoir is comprised of three distinct zones: the gas accumulation zone, the three-phase zone, and the hydrate-bearing zone. It exhibits significant commercial development potential. This paper analyzes the formation mechanism and geological context of Class 1S hydrates. A geological model was established and numerical simulation methods were employed to evaluate its production capacity, elucidating the evolutionary patterns of hydrate saturation distribution at different well locations. The simulation results indicate that production wells should be prioritised in gas accumulation zones in order to achieve the highest cumulative gas production. Additional production wells may be considered in later stages to enhance recovery rates. Secondary hydrate formation significantly impacts production in Hydrate-bearing zone and three-phase zone. Measures such as wellbore heating can be employed to minimize secondary hydrate formation around the wellbore. Full article

(This article belongs to the Special Issue Advances in Marine Gas Hydrate Exploration and Discovery—2nd Edition)

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14 pages, 2355 KB

Open AccessArticle

Evaluation of Extreme Sea Level Flooding Risk to Buildings in Samoa

by Ryan Paulik, Shaun Williams, Josephina Chan-Ting, Cyprien Bosserelle, Antonio Espejo, Moritz Wandres, Katie Pogi, Sujina Vaimagalo, Rose Pearson, Judith Giblin, Luisa Hosse, James Battersby, Juliana Ungaro, Herve Damlamian and Orisi Naivalurua

J. Mar. Sci. Eng. 2025, 13(11), 2143; https://doi.org/10.3390/jmse13112143 - 12 Nov 2025

Abstract

This study presents an economic risk evaluation of buildings in Samoa exposed to extreme sea level (ESL)-driven episodic flooding and permanent inundation from relative sea level (RSL) rise. A spatiotemporal risk analysis framework was applied at the building object level to calculate monetary [...] Read more.

This study presents an economic risk evaluation of buildings in Samoa exposed to extreme sea level (ESL)-driven episodic flooding and permanent inundation from relative sea level (RSL) rise. A spatiotemporal risk analysis framework was applied at the building object level to calculate monetary loss, expressed as the exceedance probability loss (EPL) and average annual loss (AAL). Economic risk was enumerated at national and district levels between the period 2020 and 2140 based on RSL projections for medium confidence Shared Socioeconomic Pathways (SSPs). Over this century, national AAL for buildings from ESL flooding in 2020 is expected to double by 2100 (USD 47–51 million). Under high emissions scenarios SSP3-7.0 and SSP5-8.5, AAL rates decelerate after 2100 as permanent inundation loss increases. District level risk variability is evident. For example, Tuamasaga on Upolu Island accounted for 44% of national 100-year annual recurrence interval losses, while AAL for Aiga-i-le-Tai and Va’a-o-Fonoti over this century reaches 8% of total district building replacement values. Our model approach has potential future applications to evaluate spatiotemporal risk distribution for a broader range of socioeconomic impacts that may occur beyond directly affected flood inundation areas. Full article

(This article belongs to the Section Coastal Engineering)

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33 pages, 35880 KB

Open AccessArticle

A Boundary Element Method for the Hydrodynamic Analysis of Toroidal Propellers

by Seungnam Kim

J. Mar. Sci. Eng. 2025, 13(11), 2142; https://doi.org/10.3390/jmse13112142 - 12 Nov 2025

Abstract

Toroidal propellers have emerged as a promising substitute for next-generation marine propulsors due to their potential advantages in hydrodynamic efficiency and noise control. This article presents a hydrodynamic analysis of toroidal propellers using a potential-based boundary element method (BEM) that enables rapid computations [...] Read more.

Toroidal propellers have emerged as a promising substitute for next-generation marine propulsors due to their potential advantages in hydrodynamic efficiency and noise control. This article presents a hydrodynamic analysis of toroidal propellers using a potential-based boundary element method (BEM) that enables rapid computations of complex geometries when compared with computationally demanding viscous simulations. The method predicts the inviscid flow characteristics, forces, and circulation distributions of toroidal propellers and is validated against Reynolds-averaged Navier–Stokes (RANS) simulations under various loading conditions and geometric configurations. The comparison shows that the BEM successfully reproduces the overall thrust and torque trends observed in the viscous simulations, although discrepancies arise due to flow separation and the absence of leading-edge vortices that dominate the suction side dynamics in RANS results. The wake alignment model in the BEM captures the overall trajectories of the shed vortices with good consistency, though its concentrated wake representation occasionally brings the trailing wake substantially close to the rear blade surface, which causes locally low pressures that are not present in RANS where boundary layers prevent direct wake impingement. The BEM was further extended for a parametric study that varied pitch, axial spacing, and lateral angle, showing that pitch variations have the most significant influence on propeller loading and thrust characteristics. Overall, the present work demonstrates that the proposed BEM provides a computationally efficient and physically reasonable framework for predicting the performance of toroidal propellers, especially for early-stage geometric design and optimization. Full article

(This article belongs to the Section Ocean Engineering)

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13 pages, 4540 KB

Open AccessArticle

Design and Implementation of a LiDAR-Based Inspection Device for the Internal Surveying of Subsea Pipelines

by Qingmiao Ma, Weige Liang, Haoming Chen, Qianshi Wang, Peiyi Zhou and Qingshan Wang

J. Mar. Sci. Eng. 2025, 13(11), 2141; https://doi.org/10.3390/jmse13112141 - 12 Nov 2025

Abstract

Subsea pipelines are extensively utilized in transportation systems. Conducting regular and effective internal inspections of these pipelines to promptly identify internal defects and potential risks is of paramount importance to ensure safe operational practices. In response to the practical engineering requirements for the [...] Read more.

Subsea pipelines are extensively utilized in transportation systems. Conducting regular and effective internal inspections of these pipelines to promptly identify internal defects and potential risks is of paramount importance to ensure safe operational practices. In response to the practical engineering requirements for the internal inspection of subsea pipelines, this paper presents the design of an inspection device capable of capturing point cloud data from pipelines with internal diameters of 100 mm and above and performing three-dimensional reconstruction through coding. This device clearly reveals internal pipeline defects and enables both qualitative and quantitative analyses. Upon designing the motion module, control system, and LiDAR-based detection module of the internal pipeline inspection device, the capacity to collect internal point cloud data and perform 3D reconstruction was achieved. An experimental prototype of the inspection device was manufactured and tested using a simulated pipeline constructed to replicate real-world conditions. An analysis of the inspection results demonstrates that the device can travel steadily inside the pipeline, and the collected point cloud data can be used for 3D reconstruction via coding, accurately and clearly displaying the internal 3D structure of the pipeline and its defects. This device provides a basis for the prediction of pipelines’ service lives. Full article

(This article belongs to the Special Issue Structural Modelling, Safety Assessment, and Advanced Material Application of Marine Structures)

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26 pages, 7678 KB

Open AccessArticle

Numerical Investigation of Coupled Oblique Flow and Steering Effects on Hydrodynamic Performance of Rudder Behind Propeller

by Weiguan Chen, Ronghui Li, Ji Huang, Haihui Dong, Qiqing Qiu and Qinglong Chen

J. Mar. Sci. Eng. 2025, 13(11), 2140; https://doi.org/10.3390/jmse13112140 - 12 Nov 2025

Abstract

The hydrodynamic performance of a rudder behind a propeller is critical for determining vessel maneuvering stability. During navigation, the coupled effects of the oblique flow angle (β) and the rudder angle (δ) significantly alter the wake velocity field and [...] Read more.

The hydrodynamic performance of a rudder behind a propeller is critical for determining vessel maneuvering stability. During navigation, the coupled effects of the oblique flow angle (β) and the rudder angle (δ) significantly alter the wake velocity field and vortex patterns aft of the rudder. However, the synergistic control mechanism of these two variables requires further quantitative investigation. This study employs the RANS method with the SST k-ε turbulence model to numerically simulate flow under advance coefficients (J) ranging from 0.3 to 0.9, oblique flow angles (β) from 0° to 15°, and rudder angles (δ) from 0° to 35°. Hydrodynamic coefficients, including the lift coefficient, drag coefficient, and lift-to-drag ratio, were calculated for the rudder. The evolution of the horizontal velocity and vortex fields was captured, with the model validated through localized flow field visualization. The results reveal that when β ≤ 3°, δ is the dominant factor influencing rudder hydrodynamics. Conversely, when β ≥ 9°, β becomes the primary regulating factor. The coupling effect induces significant asymmetry in the velocity distribution across the rudder surfaces and pronounced flow separation on the windward side, generating a complex vortex system (including primary and secondary vortices) on the leeward side. This research elucidates the coupled control mechanism of oblique flow and rudder angle, providing insights for enhancing steering margins and a quantitative foundation for optimizing rudder profiles in challenging sea environments characterized by high oblique flow and large rudder angles. Full article

(This article belongs to the Special Issue Ship Manoeuvring and Control)

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