Journal of Marine Science and Engineering

32 pages, 18145 KB

Open AccessArticle

Elliptical Disk-Based Collision Avoidance for Formation Tracking Control of Underactuated Surface Vessels Under Input Saturation

by Yafei Ge and Xiaoming Xia

J. Mar. Sci. Eng. 2026, 14(16), 1557; https://doi.org/10.3390/jmse14161557 - 21 Aug 2026

Viewed by 250

Abstract

This paper investigates a formation tracking problem for underactuated surface vessels (USVs) subject to collision avoidance and input saturation constraints. Many existing APF-based formation-control approaches formulate collision avoidance using a single reference point or an inter-center distance, which may provide insufficient geometric information [...] Read more.

This paper investigates a formation tracking problem for underactuated surface vessels (USVs) subject to collision avoidance and input saturation constraints. Many existing APF-based formation-control approaches formulate collision avoidance using a single reference point or an inter-center distance, which may provide insufficient geometric information during close-range maneuvers. To improve navigation safety, an elliptical disk-based collision avoidance mechanism is developed by introducing safety points at the bow, stern, port, and starboard sides of each USV, such that multiple characteristic-point distance constraints can be simultaneously enforced. To address unknown nonlinearities caused by model uncertainties and external disturbances, a neural network-based observer is designed to estimate unavailable velocity states and lumped disturbances. Distributed control laws are synthesized by integrating artificial potential functions (APFs), the observer, and a backstepping technique. Additional controllers are introduced to address the input saturation and underactuated issues while preserving the collision avoidance capability. Stability of the closed-loop system is rigorously established via Lyapunov theory. Simulation results demonstrate that the proposed approach achieves safer close-range maneuvering performance compared with conventional single-point methods. Full article

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25 pages, 19964 KB

Open AccessArticle

Influence of Strain Softening on the Penetration Characteristics of an Annular Suction Caisson in Nonhomogeneous Clay

by Yuqi Wu, Yuanzheng Yang and Hao Liang

J. Mar. Sci. Eng. 2026, 14(16), 1556; https://doi.org/10.3390/jmse14161556 - 21 Aug 2026

Viewed by 235

Abstract

This paper proposes an annular suction caisson specifically designed to reinforce in-service monopiles and upgrade existing offshore wind farms to accommodate larger-capacity wind turbines. During penetration of the annular suction caisson into clay, the existing monopile restricts the inward migration of soil into [...] Read more.

This paper proposes an annular suction caisson specifically designed to reinforce in-service monopiles and upgrade existing offshore wind farms to accommodate larger-capacity wind turbines. During penetration of the annular suction caisson into clay, the existing monopile restricts the inward migration of soil into the internal space of the caisson, promoting upward soil displacement and consequently increasing the height of the soil plug formed inside the caisson. In addition, the strain-softening behavior causes varying degrees of strength degradation in the clay along the caisson wall. The softened zones extend approximately one caisson wall thickness on the inner side and 1.2 times the wall thickness on the outer side of the caisson. Both effects should be considered for accurately predicting the penetration resistance of annular suction caissons. Therefore, three-dimensional large-deformation finite element analyses were performed to investigate the penetration behavior of annular suction caissons in strain-softening clay. A comprehensive parametric study was conducted to quantify the soil plug heave and overall penetration resistance. Meanwhile, the soil flow mechanism at the caisson tip, the evolution of clay strength along the caisson wall, and the formation characteristics of the internal soil plug were systematically examined. Based on the numerical results, a theoretical approach was developed to evaluate the penetration resistance of annular suction caissons. Full article

(This article belongs to the Section Ocean Engineering)

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22 pages, 87108 KB

Open AccessArticle

A Statistical Quality-Control Framework for Sentinel-1 SAR Wind Speed Retrieval Based on First- and Second-Order Moments

by Yan Wang, Xupu Geng, Yan Li, Xiaohui Li, Chenghan Luo, Shaoping Shang and Feng Zhang

J. Mar. Sci. Eng. 2026, 14(16), 1555; https://doi.org/10.3390/jmse14161555 - 21 Aug 2026

Viewed by 225

Abstract

Synthetic Aperture Radar (SAR) enables high-resolution sea-surface wind speed retrieval. However, the enhanced spatial resolution of SAR imagery introduces substantial challenges, from small-scale contamination sources that significantly degrade retrieval accuracy. Particularly in coastal regions, non-wind-related backscatter signals, such as ships and oil slicks, [...] Read more.

Synthetic Aperture Radar (SAR) enables high-resolution sea-surface wind speed retrieval. However, the enhanced spatial resolution of SAR imagery introduces substantial challenges, from small-scale contamination sources that significantly degrade retrieval accuracy. Particularly in coastal regions, non-wind-related backscatter signals, such as ships and oil slicks, can severely bias wind speed estimates at sub-kilometer scales. In this study, the first-order moment (average, m₁) and second-order moment (variance, m₂) are computed from the normalized radar cross-section (NRCS) within sub-images of Sentinel-1 SAR data acquired in Interferometric Wide (IW) mode. Analysis reveals that clean-sea-surface signals in both VV and VH polarizations cluster around an approximately linear empirical trend, m₂ = 2m₁ + b, in the m₁-m₂ statistical feature space, whereas the examined contamination types deviate from this trend and occupy separable regions. Based on this characteristic, a quality-control framework is proposed for the systematic separation of clean sea surface from image noise (border noise and inter-swath stripe noise) and non-ocean targets (land contamination, bright targets, and dark spots). Validation using independent SAR data from the Taiwan Strait was conducted separately for native 10 m and height-adjusted 3 m buoy observations. For the native 10 m observations, the RMSE and MBE were essentially unchanged at 1.5 m/s and −0.3 m/s, respectively. For the height-adjusted nearshore observations, the RMSE decreased from 3.2 m/s to 2.1 m/s and the MBE changed from −1.5 m/s to −1.1 m/s. Full article

(This article belongs to the Section Physical Oceanography)

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19 pages, 2220 KB

Open AccessArticle

Phenological Shifts and Photosynthetic Trade-Offs in Phragmites australis Under Experimental Warming: A Seasonal Perspective

by Ke Zhang, Liujuan Xie, Siyuan Ye, Ken W. Krauss, Lei He, Xigui Ding, Shixiong Yang, Pan Zhou, Zongmin Zhu, Thomas J. Mozdzer, Samantha K. Chapman, Brian K. Sorrell, Edward A. Laws and Hans Brix

J. Mar. Sci. Eng. 2026, 14(16), 1554; https://doi.org/10.3390/jmse14161554 - 21 Aug 2026

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Abstract

Although climate warming affects photosynthetic carbon sequestration in coastal wetland plants, the seasonality of this effect has not been assessed. We investigated the growth traits and photosynthetic properties of Phragmites australis by using open-top chambers (OTCs) to conduct a warming experiment in the [...] Read more.

Although climate warming affects photosynthetic carbon sequestration in coastal wetland plants, the seasonality of this effect has not been assessed. We investigated the growth traits and photosynthetic properties of Phragmites australis by using open-top chambers (OTCs) to conduct a warming experiment in the coastal wetlands of the Yellow River Delta during a single growing season. The OTCs significantly elevated temperatures by ~1 °C across the growing season, and the effects of warming on stem diameter, net photosynthetic rate (P_n), and water use efficiency (WUE) were characterized by a significant month × warming interaction. Early-season carboxylation efficiency (φ) increased by 71%, but a significant late-season decline of P_n by 49% accompanied by a rise of intercellular CO₂ concentrations (C_i) and decline of stomatal limitation (L_s) led to a seasonal shift from stomatal to non-stomatal (biochemical) limitation of growth. A consistent increase in plant height and C_i across all months and concomitant decrease in L_s indicated that the additive effects of warming were independent of phenological stage. The results revealed that the phenological mediation of warming responses is trait specific. Carbon cycle models should therefore adopt trait-specific parameterizations to accurately project the impact of the wetland carbon sink under future warming. Full article

(This article belongs to the Topic Dynamic Monitoring and Estimation of Coastal Wetland Blue Carbon Ecosystems)

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28 pages, 784 KB

Open AccessArticle

A Polarization-Space-Time Detector Without Secondary Data in Compound-Gaussian Clutter

by Yaomin He, Yimin Yang, Zheng Li, Liyuan Wang and Jian Yang

J. Mar. Sci. Eng. 2026, 14(16), 1553; https://doi.org/10.3390/jmse14161553 - 21 Aug 2026

Viewed by 347

Abstract

Since heavy clutter seriously restricts the ability of radar to detect targets, it is significant to build the target detector under heavy clutter. For practical situations without the secondary data or prior knowledge of target and clutter, this paper proposes a polarization-space-time detector. [...] Read more.

Since heavy clutter seriously restricts the ability of radar to detect targets, it is significant to build the target detector under heavy clutter. For practical situations without the secondary data or prior knowledge of target and clutter, this paper proposes a polarization-space-time detector. First, a general radar model is constructed for multiple pulses, multiple arrays, and multiple polarizations. Based on the theory of ternary hypothesis, the secondary data free (SDF) GLRT detector is proposed, which can maintain the constant false alarm probability (CFAR) in inhomogeneous clutter. Then, this paper proposes a matrix transform operator and an adaptive detection method using sliding window. These two approaches do not need to know the steering vector of radar and the noncentral parameter of clutter in advance, so the SDF-GLRT detector can adapt to different application scenarios. In addition, this paper optimizes the polarization waveform of the radar system by constructing a projection matrix. This method yields closed-form solutions of the optimal polarization and worst polarization, rather than relying on numerical solution. Finally, the performances of the SDF-GLRT detector and three other detectors are compared by simulated and real data. The proposed SDF-GLRT maintains

P_{FA}

of

5.4 \times 10^{- 3}

and

2.6 \times 10^{- 3}

on two IPIX datasets (#54 and #310) at a design

P_{FA} = 10^{- 3}

, whereas the other detectors deviate to

0.0249

–

0.7405

. The optimal polarization yields a detection-probability gain of more than

0.22

over the worst polarization at

SCR = 0

dB. Full article

(This article belongs to the Special Issue Applications of Sensors in Marine Observation)

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28 pages, 32139 KB

Open AccessArticle

Nonlinear Effects of Background Currents on Low-Mode Internal Tides from the Luzon Strait

by Jiaqi Guo, Pengyang Song, Hao Huang and Xueen Chen

J. Mar. Sci. Eng. 2026, 14(16), 1552; https://doi.org/10.3390/jmse14161552 - 21 Aug 2026

Viewed by 267

Abstract

The Luzon Strait is a critical generation site for global internal tides. Their generation and propagation are significantly modulated by background currents, including the Kuroshio Current and mesoscale eddies. This study investigates nonlinear effects of these background currents on low-mode (modes 1–3) internal [...] Read more.

The Luzon Strait is a critical generation site for global internal tides. Their generation and propagation are significantly modulated by background currents, including the Kuroshio Current and mesoscale eddies. This study investigates nonlinear effects of these background currents on low-mode (modes 1–3) internal tides using a high-resolution numerical simulation. We apply the Taylor–Goldstein equation considering the Earth’s rotation and background currents to perform modal decomposition, and utilize a nonlinear internal tidal energy equation to quantify three crucial energy pathways: inter-modal energy conversion, nonlinear energy exchange with background currents, and nonlinear advection effects. Results demonstrate that while stationary mode-1 internal tides dominate in the generation region of the Luzon Strait, non-stationary energy increases significantly in the western and eastern propagation regions, driven largely by seasonal variability of the Kuroshio Current. Inter-modal energy conversion follows a cascade from lower to higher modes, with conversion efficiency increasing with mode number. Nonlinear exchanges between background currents and internal tides are one order of magnitude smaller than inter-modal conversions but exhibit a bidirectional transfer, where advection redistributes internal tidal energy within the eddy structures. This study provides a quantitative framework for understanding multiscale energy pathways of internal tides under complex ocean dynamics. Full article

(This article belongs to the Section Physical Oceanography)

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21 pages, 1556 KB

Open AccessReview

Life Cycle Assessment, Life Cycle Cost and Ship Design Optimisation for Sustainable Electric Ships: A Review

by Sharul Baggio Roslan, Xin Wang and Chunwee Ng

J. Mar. Sci. Eng. 2026, 14(16), 1551; https://doi.org/10.3390/jmse14161551 - 21 Aug 2026

Viewed by 422

Abstract

This paper reviews the application of Life Cycle Assessment (LCA), Life Cycle Cost Assessment (LCCA), and ship design optimisation methods and examines the extent to which these approaches have been integrated to support sustainable electric ship design. The main goal is to understand [...] Read more.

This paper reviews the application of Life Cycle Assessment (LCA), Life Cycle Cost Assessment (LCCA), and ship design optimisation methods and examines the extent to which these approaches have been integrated to support sustainable electric ship design. The main goal is to understand how these methods have been applied and where the key gaps remain. The review analyses current practices in environmental and cost assessments of ship systems and design, along with ship design optimisation methods aimed at improving energy efficiency and reducing emissions. Overall, the reviewed literature shows that LCA, LCCA, and ship design optimisation are generally applied as separate processes rather than parts of an integrated framework. Key gaps include the lack of models that account for time-varying costs, changes in technology and energy systems. Additionally, this paper highlights the need for integrated and adaptive frameworks, supported by open and standardised data and digital tools, to better connect environmental and economic considerations across a vessel’s life cycle, for more practical and sustainable ship design. Full article

(This article belongs to the Special Issue Advances in Maritime Decarbonization: Technologies and Operations Towards Zero-Emission Ports and Vessels)

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29 pages, 3015 KB

Open AccessArticle

Multimodal-Augmented Conditional Diffusion Model for Maritime Waypoint-Level Tropical Cyclone Intensity Prediction

by Yongfei Zheng and Guosun Zeng

J. Mar. Sci. Eng. 2026, 14(16), 1550; https://doi.org/10.3390/jmse14161550 - 21 Aug 2026

Viewed by 319

Abstract

Accurately forecasting waypoint-level tropical cyclone (TC) intensity, defined as the local wind speed at specific maritime route waypoints under TC influence, is crucial for navigation safety and voyage planning. Conventional studies mainly focus on the central intensity of TC systems and underutilize the [...] Read more.

Accurately forecasting waypoint-level tropical cyclone (TC) intensity, defined as the local wind speed at specific maritime route waypoints under TC influence, is crucial for navigation safety and voyage planning. Conventional studies mainly focus on the central intensity of TC systems and underutilize the complementary value of multimodal meteorological data with inconsistent sampling intervals. To address these challenges, this study proposes a multimodal-augmented conditional diffusion model (MADiff) for waypoint-level TC intensity prediction. To exploit the potential of multimodal inputs, we first design a temporal-adaptive dynamic convolution module (TDConv) to capture multi-timescale features, mitigating multimodal sampling discrepancies without rigid temporal alignment. Second, we develop a discriminative cross-fusion module (DisCF) to aggregate multi-timescale features across diverse modalities, quantifying multimodal heterogeneity and integrating valuable modality-specific features while suppressing noise interference. Fused features are fed into a diffusion model with physics-informed regularization to generate final intensity forecasts. Extensive experiments on four Western North Pacific datasets show that MADiff achieves average MAE and RMSE values of 2.08 kt and 2.37 kt, respectively, for 12 h intensity forecasting. Compared with the state-of-the-art baseline (TC-Clouds-DP), MADiff yields substantial performance improvements, reducing MAE by 16.3% and RMSE by 10.6% on average. This study provides an effective framework for fine-grained TC intensity forecasting, offering valuable insights for extreme marine weather early warning and intelligent navigation decision-making. Full article

(This article belongs to the Special Issue Artificial Intelligence Technology and Application in Marine Science and Engineering)

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22 pages, 36189 KB

Open AccessArticle

Spatial Heterogeneity of Long-Term Sandy Shoreline Change Along Eastern Hainan Island, China (1987–2025)

by Yuanting Ding, Yi Liu, Qiyi Du and Jitao Yu

J. Mar. Sci. Eng. 2026, 14(16), 1549; https://doi.org/10.3390/jmse14161549 - 21 Aug 2026

Viewed by 308

Abstract

Long-term shoreline change on tropical islands is spatially heterogeneous, but alongshore contrasts remain insufficiently resolved. We quantified shoreline change along the 151.1 km eastern sandy coast of Hainan Island, China, from 1987 to 2025 using Landsat-derived visually interpreted shoreline proxies and the Digital [...] Read more.

Long-term shoreline change on tropical islands is spatially heterogeneous, but alongshore contrasts remain insufficiently resolved. We quantified shoreline change along the 151.1 km eastern sandy coast of Hainan Island, China, from 1987 to 2025 using Landsat-derived visually interpreted shoreline proxies and the Digital Shoreline Analysis System across 1413 transects. The coast was broadly stable to accretional, with a mean linear regression rate (LRR) of 0.49 m/yr and a mean net shoreline movement (NSM) of 17.72 m. Under the uncertainty-aware classification, 28.0% of transects were stable, 42.1% accretional, 8.2% erosional, and 21.7% indeterminate. For descriptive comparison, the eight sectors were grouped into three broad alongshore zones: a stable northern zone (Beaches A–B), an accretion-dominated central zone (Beaches C–E), and a heterogeneous southern zone (Beaches F–H). The strongest accretion occurred at Beach D (LRR = 7.63 m/yr), whereas the strongest erosion occurred south of the offshore artificial island at Beach F (LRR = −3.97 m/yr). These contrasts show that coast-wide stability or accretion can mask localized erosion. The observed patterns were spatially associated with differences in headland-bay morphology, nearshore seagrass beds, engineering structures, estuarine processes, and lagoon-inlet settings. The findings support beach-sector monitoring and differentiated coastal management. Full article

(This article belongs to the Section Coastal Engineering)

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38 pages, 15036 KB

Open AccessArticle

Circumferential Response Differences and Plastic Deformation Mechanisms of Ring-Stiffened Cylindrical Shells Subjected to Underwater Explosion Shock Waves

by Kaifeng Zhang and Zhenhua Zhang

J. Mar. Sci. Eng. 2026, 14(16), 1548; https://doi.org/10.3390/jmse14161548 - 21 Aug 2026

Viewed by 276

Abstract

Ring-stiffened cylindrical shells are widely used as load-bearing components in submarine pressure-hull sections. Existing underwater explosion studies have mainly emphasized incident-face denting or global failure, leaving unresolved how circumferential shock-wave diffraction and internal structural load transfer produce different response sequences and plastic-strain accumulation [...] Read more.

Ring-stiffened cylindrical shells are widely used as load-bearing components in submarine pressure-hull sections. Existing underwater explosion studies have mainly emphasized incident-face denting or global failure, leaving unresolved how circumferential shock-wave diffraction and internal structural load transfer produce different response sequences and plastic-strain accumulation at the incident, side, and rear faces. A mechanism-oriented underwater explosion model test was conducted using a 44 g TNT charge at a stand-off distance of 0.50 m, and a fluid–structure interaction model was established in MSC.Dytran using the general coupling method. The model incorporated the Cowper–Symonds strain-rate effect of 16MnR steel and was validated against the Cole empirical peak pressure and measured incident-face residual deformations. The calculated free-field peak pressure was 35.50 MPa, with an error of 0.65%, while the mean relative error of the six residual-deformation measurements was 13.50%. The shell plating between adjacent ring stiffeners exhibited higher velocity and acceleration peaks than the stiffeners, indicating the local constraint imposed by the ring stiffeners. The side-face nodes showed symmetric transverse expansion, and the corresponding elements exhibited no discernible equivalent plastic strain. The rear-face center displayed a delayed axial response, and its representative element reached a final equivalent plastic strain of approximately

1.32 \times 10^{- 3}

, compared with

0.40 \times 10^{- 3}

for the incident-face element. These results identify distinct circumferential response modes and show that macroscopic motion amplitude is not simply correlated with local plastic deformation. Full article

(This article belongs to the Section Ocean Engineering)

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20 pages, 30448 KB

Open AccessArticle

Identification of Hull Vertical Bending Moment Based on a Temporal Convolutional Network and Section Method Parameter Correction

by Kai Zheng, Huanqiu Xu, Hongyu Cui and Xianqiang Qu

J. Mar. Sci. Eng. 2026, 14(16), 1547; https://doi.org/10.3390/jmse14161547 - 21 Aug 2026

Viewed by 251

Abstract

Real-time monitoring of wave-induced loads supports ship masters’ scientific navigation decisions, where vertical bending moment is a core index representing hull longitudinal bending under waves. This paper combines a temporal convolutional network with the traditional section method to build a vertical bending moment [...] Read more.

Real-time monitoring of wave-induced loads supports ship masters’ scientific navigation decisions, where vertical bending moment is a core index representing hull longitudinal bending under waves. This paper combines a temporal convolutional network with the traditional section method to build a vertical bending moment identification model embedded with a section parameter correction mechanism. The main work includes the following: multiple wave condition strain–load datasets are generated via numerical simulations to train the model; the section method calibrates model parameters to boost prediction precision; and wave load tests are conducted to verify the model’s practicability. Results indicate the section method offers physical constraints that embed ship sectional features into the model, lifting identification accuracy, robustness and result rationality. This work applies a temporal convolutional network to the hull vertical bending moment identification with section parameter correction, offering technical references for hull structural safety evaluation and intelligent maritime decision-making. Full article

(This article belongs to the Special Issue Advanced Analysis of Ship and Offshore Structures)

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21 pages, 14199 KB

Open AccessArticle

A Combined Smoothed Particle Hydrodynamics and Discrete Element Method Approach for Granular Collapse and Induced Wave Generation: Validations and Performance Test

by Jiazhao Sun, Li Zou, Nicolin Govender, Zhimin Zhao, Yingjie Hu and Xiangqian Fan

J. Mar. Sci. Eng. 2026, 14(16), 1546; https://doi.org/10.3390/jmse14161546 - 20 Aug 2026

Viewed by 286

Abstract

Granular collapse-induced wave generation is a critical process in coastal engineering and natural hazards, yet its rapid and complex fluid–solid coupling mechanism poses significant challenges for numerical modeling. This paper presents a comprehensive validations and performance benchmarking study of non-spherical granular collapse-induced wave [...] Read more.

Granular collapse-induced wave generation is a critical process in coastal engineering and natural hazards, yet its rapid and complex fluid–solid coupling mechanism poses significant challenges for numerical modeling. This paper presents a comprehensive validations and performance benchmarking study of non-spherical granular collapse-induced wave generation using a GPU-accelerated resolved SPH-DEM coupling framework. Through three benchmark cases with increasing complexity, the numerical accuracy and robustness of the model are thoroughly verified with respect to free-surface flows, multi-body collisions, and intense fluid–solid interactions. Subsequently, the influence of SPH resolution and particle shape on computational efficiency is quantitatively assessed. It is found that the total runtime is dominated by the number of SPH particles, while the GPU acceleration advantage becomes more pronounced as the number of DEM faces increases. Furthermore, in the granular collapse-induced wave case, the temporal evolution of the leading wave amplitude and the difference in granular runout distance under dry and wet conditions are analyzed, revealing from the particle scale how fluid resistance modulates the coupling between wave generation and granular motion. This study not only validates the capability of the model to capture complex particle–wave interactions, but also provides quantifiable performance benchmarks and physical insights for its engineering applications. Full article

(This article belongs to the Special Issue Advances of Multiphase Flow in Hydraulic and Marine Engineering)

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27 pages, 51293 KB

Open AccessArticle

An IoT Sensor System for Marine and Coastal Aquaculture Monitoring with Blockchain-Backed Data Provenance

by Dejan Drajić, Tomo Popović, Srđan Krčo, Nikola Vojičić, Nives Ogrinc and Vladimir D. Urošević

J. Mar. Sci. Eng. 2026, 14(16), 1545; https://doi.org/10.3390/jmse14161545 - 20 Aug 2026

Viewed by 427

Abstract

Aquaculture requires continuous environmental monitoring, yet low-cost IoT sensing in marine conditions remains poorly characterised, and the data it produces is rarely accompanied by mechanisms establishing its provenance. This paper presents an IoT sensor system for marine and coastal aquaculture, comprising solar-powered 4G [...] Read more.

Aquaculture requires continuous environmental monitoring, yet low-cost IoT sensing in marine conditions remains poorly characterised, and the data it produces is rarely accompanied by mechanisms establishing its provenance. This paper presents an IoT sensor system for marine and coastal aquaculture, comprising solar-powered 4G multiparameter nodes, a cloud-native back-end with a RESTful layer, and integration with a blockchain-based change-detection mechanism supplying a GS1-compliant digital product passport. Four nodes in adjacent cages were deployed at a marine site on the Montenegrin Adriatic for eight weeks, measuring temperature, pH, dissolved oxygen, oxidation–reduction potential and conductivity at five-minute resolution. Lacking reference instrumentation, we use agreement between nodes for validation. Temperature showed the closest cross-node agreement, with nodes agreeing to within 0.28 °C, and resolved a coherent cold, low-salinity intrusion detected simultaneously by all four nodes. The electrochemical and optical channels proved precise but not accurate: they tracked relative change coherently while their absolute values diverged, with oxidation–reduction potential moving from 9 mV of agreement to 71 mV over the following weeks. Cross-node coherence in conductivity and dissolved oxygen degraded progressively over the deployment, with no electrochemical or optical channel remaining coherent beyond roughly six weeks. Such sensors suit anomaly detection without calibration but require periodic recalibration for absolute reporting. Tamper-evident provenance is therefore necessary but not sufficient: sensor-level quality assurance is its missing half. Full article

(This article belongs to the Special Issue Novel Advances in Offshore Sensor Systems)

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25 pages, 28602 KB

Open AccessArticle

Research on Hydrodynamic Performance of a 30 kW Rim-Driven Thruster and Its Coupling Mechanism with an AUV

by Xia Yang, Kunkun Li, Xiong Deng, Dingfeng Yu, Yiyun Peng, Yan Luo and Yanyang Wu

J. Mar. Sci. Eng. 2026, 14(16), 1544; https://doi.org/10.3390/jmse14161544 - 20 Aug 2026

Viewed by 318

Abstract

With the continuous expansion of deep-sea resource exploration, marine environmental monitoring, and underwater operations, Autonomous Underwater Vehicles (AUVs) have been increasingly widely applied. Aiming at the demand for high-performance main propulsion systems of Autonomous Underwater Vehicles (AUVs), this paper conducts research on the [...] Read more.

With the continuous expansion of deep-sea resource exploration, marine environmental monitoring, and underwater operations, Autonomous Underwater Vehicles (AUVs) have been increasingly widely applied. Aiming at the demand for high-performance main propulsion systems of Autonomous Underwater Vehicles (AUVs), this paper conducts research on the structural design and hydrodynamic performance of a 30 kW rim-driven thruster (RDT) and its coupling mechanism with AUVs. By combining computational fluid dynamics (CFD) simulations and experimental methods, the influence of the advance coefficient on the open-water performance of the thruster is revealed. An integrated coupling simulation model of the AUV and RDT is established to analyze the performance attenuation law of the thruster and the characteristics of the coupled flow field under wake flow conditions, and to clarify the two-way interaction mechanism between the thruster and AUV. Towing tank tests were carried out at sailing speeds ranging from 1 to 4 kn, which verifies the reliability of the numerical simulation model and the matching performance between the thruster and AUV. The results show that the open-water efficiency of the thruster reaches a peak value of 0.536 at the advance coefficient

J = 0.8

, which is close to the optimal efficiency range with good matching performance of the propulsion system Under wake flow conditions, the attenuation range of the thrust coefficient of the thruster is 12.45–16.53% with the increase in advance coefficient. The main reasons are the uneven inflow velocity and unstable flow field pressure distribution caused by the non-uniform wake flow at the AUV stern. At the ship speeds of 2 kn, 3 kn and 4 kn, the self-propulsion rotational speeds obtained from test fitting are in good agreement with the simulation results, with all relative errors less than 8%. This study provides a theoretical basis and technical reference for the engineering design of medium and high-power rim-driven thrusters as well as the matching optimization of AUV-thruster systems. Full article

(This article belongs to the Section Ocean Engineering)

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16 pages, 2378 KB

Open AccessArticle

Efficient Preparation of Uniform Saturated Marine Clay via a Combined Vacuum–Capillary Technique

by Long Yu, Xingsheng Zhao, Yunrui Han, Li Cheng, Xiaowei Feng, Gang Yang and Qing Yang

J. Mar. Sci. Eng. 2026, 14(16), 1543; https://doi.org/10.3390/jmse14161543 - 20 Aug 2026

Viewed by 272

Abstract

Model testing is an important method for investigating the interaction between marine structures and soil, and the preparation of high-quality saturated clay samples plays a crucial role in laboratory testing. In this study, a new method for preparing saturated soil samples was developed [...] Read more.

Model testing is an important method for investigating the interaction between marine structures and soil, and the preparation of high-quality saturated clay samples plays a crucial role in laboratory testing. In this study, a new method for preparing saturated soil samples was developed by combining vacuum extraction and permeation saturation, and its performance was validated through laboratory experiments. A series of laboratory tests, including the gravity and cutting-ring methods, was conducted on columnar soil samples to evaluate the impact of this new technique on soil properties. The results indicate that the soil samples prepared using the new method achieved saturation levels of at least 97% and spatial uniformity. In addition, a large-volume saturated clay sample preparation method was designed and experimentally validated specifically for large-scale model tests. Soil samples were prepared in a model box with dimensions of 300 mm (L_rec) × 300 mm (W_rec) × 200 mm (D_rec) in 24–48 h. Both the T-bar penetration and vane shear tests were performed on the prepared soil samples to measure their undrained shear strength. The results show that the middle and lower layers of the large-volume soil samples exhibited spatial uniformity. Full article

(This article belongs to the Special Issue Selected Papers from the 5th International Joint Conference on Civil and Marine Engineering (JCCME 2026))

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33 pages, 66081 KB

Open AccessArticle

Monitoring and Assessment of Coastal Hazard Potential Induced by Reclamation-Related Subsidence: An Integrated InSAR and Coastline-Change Approach in Fangchenggang, China

by Yafei Sun, Kaijie Yang, Miaomiao Zhang, Mingsheng Zhang and Juanjuan Tang

J. Mar. Sci. Eng. 2026, 14(16), 1542; https://doi.org/10.3390/jmse14161542 - 20 Aug 2026

Viewed by 422

Abstract

Land subsidence in coastal reclamation areas has emerged as one of the critical hidden hazards for coastal cities. This paper presents an integrated InSAR and coastline-change framework for land subsidence monitoring and driving-factor analysis in coastal reclamation cities. Taking the Fangchenggang City, China, [...] Read more.

Land subsidence in coastal reclamation areas has emerged as one of the critical hidden hazards for coastal cities. This paper presents an integrated InSAR and coastline-change framework for land subsidence monitoring and driving-factor analysis in coastal reclamation cities. Taking the Fangchenggang City, China, as the study area, we utilized 266 scenes of Sentinel-1A SAR images (2016–2025) from the European Space Agency (ESA) and applied time-series SBAS-InSAR to obtain a 10-year time-series monitoring result of land subsidence, with cross-validation against PS-InSAR showing an RMSE below 4 mm at four checkpoints. Furthermore, influencing factors were analyzed by integrating data on coastline changes, precipitation, and groundwater indicators. The conclusions of this paper are as follows: (1) Seven distinct land subsidence funnels in Fangchenggang City from 2016 to 2025 were identified for the first time. Spatially, land subsidence exhibits significant heterogeneity, primarily concentrated in the coastal reclamation areas of the Qisha Peninsula and the Yuwan Peninsula, the maximum subsidence rate reached as high as −163.53 ± 4.90 mm/yr. Temporally, the subsidence rate in the study area shows a gradual deceleration trend over time. (2) The coastline change results from 1964 to 2025 reveal a three-stage temporal characteristic: the land area increased by 2.23 ± 4.51 km², 14.28 ± 6.19 km², and 23.31 ± 4.51 km² during the periods of 1964–1995, 1995–2008, and 2008–2025, respectively. The time-series InSAR results and coastline change results demonstrate that coastal reclamation is the primary factor contributing to land subsidence in this study area. (3) Apart from land reclamation, driving factors such as precipitation and groundwater indicators also show a slight correlation with land subsidence. Full article

(This article belongs to the Special Issue Coastal Disaster Assessment and Response—2nd Edition)

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27 pages, 10255 KB

Open AccessArticle

Safety-Enhanced COLREGs-Compliant Path Planning for USVs with a CBF-Based Safety Shield

by Sung-Jo Yun, Hyogon Kim, Ji-Wook Kwon, Young-Ho Choi, Dong-Hoon Kim, Woong-Ki Lee, Ji-Wan Kim and Jun-Hyuk Choi

J. Mar. Sci. Eng. 2026, 14(16), 1541; https://doi.org/10.3390/jmse14161541 - 19 Aug 2026

Viewed by 299

Abstract

This study proposes a safety-enhanced path planning system that integrates a Control Barrier Function (CBF)-based Safety Shield with Deep Reinforcement Learning (DRL). This framework addresses the critical limitations of conventional DRL-based Unmanned Surface Vehicle (USV) navigation models, which can output hazardous control commands [...] Read more.

This study proposes a safety-enhanced path planning system that integrates a Control Barrier Function (CBF)-based Safety Shield with Deep Reinforcement Learning (DRL). This framework addresses the critical limitations of conventional DRL-based Unmanned Surface Vehicle (USV) navigation models, which can output hazardous control commands in edge cases and violate the International Regulations for Preventing Collisions at Sea (COLREGs). The proposed system continuously operates during navigation via an Encounter Classifier that identifies multi-vessel situations (such as Head-on, Crossing, and Overtaking) in real time. The nominal control inputs generated by the DRL policy are verified and safely filtered through a Control Barrier Function-Quadratic Programming (CBF-QP) optimization layer immediately prior to execution, incorporating ship safety radii and asymmetric COLREGs constraints. Furthermore, we introduce a ‘Shielded Training’ mechanism that penalizes the agent based on the magnitude of the shield’s interventions during the training loop. This effectively diminishes the policy’s over-reliance on the safety filter and guides the network toward discovering robust, inherently safe trajectories. Extensive simulations conducted under diverse single- and multi-vessel encounter scenarios quantitatively demonstrate that the proposed method substantially reduces collision and COLREGs violation rates compared to baseline DRL-only or reward-shaping methods, while maintaining excellent computational scalability and real-time responsiveness. Consequently, by unifying the adaptive environmental exploration of reinforcement learning with model-based runtime safety constraints derived from control theory, this study provides a practical runtime assurance framework for future marine deployment. Full article

(This article belongs to the Section Ocean Engineering)

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18 pages, 2684 KB

Open AccessArticle

A PI-DeepONet-Based Rapid and Accurate Wide-Area ELF Computation Method for Smart Ocean Sensing with Theoretical and Experimental Validations

by Yong Yang, Weijie Wang, Yongkai Liu, Zhaoyang Yuan, Xiaobing Zhang, Jun Ouyang and Changsong Cai

J. Mar. Sci. Eng. 2026, 14(16), 1540; https://doi.org/10.3390/jmse14161540 - 19 Aug 2026

Viewed by 351

Abstract

Rapid three-dimensional electromagnetic field simulation in stratified marine environments is essential for underwater target sensing system design. This paper presents a Physics-Informed Deep Operator Network (PI-DeepONet) that integrates analytical Sommerfeld integral solutions with seafloor experimental measurements to establish a validated, mesh-free forward modeling [...] Read more.

Rapid three-dimensional electromagnetic field simulation in stratified marine environments is essential for underwater target sensing system design. This paper presents a Physics-Informed Deep Operator Network (PI-DeepONet) that integrates analytical Sommerfeld integral solutions with seafloor experimental measurements to establish a validated, mesh-free forward modeling framework for extremely low-frequency (ELF) electromagnetic propagation. The architecture uses Fourier feature encoding to resolve multiscale dipole fields and incorporates Maxwell’s divergence constraint through automatic differentiation. The model is evaluated using a tiered validation strategy that combines analytical benchmarks, controlled seafloor experiments, and comparison with a purely data-driven DeepONet. The results show close agreement across stratified marine scenarios, improved accuracy and physical consistency from the embedded constraint, and substantially faster pointwise inference than conventional finite element solvers. Analysis of near-field discrepancies further identifies seabed anisotropy and environmental uncertainty as important sources of model–experiment mismatch, thereby clarifying the framework’s applicability and limitations for marine sensing-system design. Full article

(This article belongs to the Special Issue Underwater Wireless Power Transfer Systems)

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22 pages, 1850 KB

Open AccessArticle

Bayesian Fusion Based Robust Array Shape Estimation for Distorted Towed Hydrophone Array

by Chuanqi Zhu, Jiani Zhang, Yitong Li and Liang An

J. Mar. Sci. Eng. 2026, 14(16), 1539; https://doi.org/10.3390/jmse14161539 - 19 Aug 2026

Viewed by 245

Abstract

Towed hydrophone arrays are widely employed for underwater target detection and direction-of-arrival (DOA) estimation. However, array shape distortion induced by ocean currents, internal waves, and platform maneuvers severely degrades beamforming performance and DOA estimation accuracy. In this paper, a novel Bayesian fusion framework [...] Read more.

Towed hydrophone arrays are widely employed for underwater target detection and direction-of-arrival (DOA) estimation. However, array shape distortion induced by ocean currents, internal waves, and platform maneuvers severely degrades beamforming performance and DOA estimation accuracy. In this paper, a novel Bayesian fusion framework is proposed to achieve robust array shape estimation. Specifically, based on the time-delay estimates derived from the phase differences of line-spectrum components in a pre-processing step, the array geometry is first reconstructed via a piecewise straight-line fitting method. Concurrently, an existing hidden Markov model (HMM)-based method is adopted to estimate the inter-segment deviation angles, in which the smoothness of the array shape is enforced through the state-transition probabilities. The proposed framework then treats these two preliminary estimates as observations from distinct sources and incorporates a smoothness prior within a maximum a posteriori (MAP) formulation that admits a non-iterative closed-form solution to enforce physical continuity constraints on the array geometry. By fusing these complementary estimates, the proposed method simultaneously preserves local sensitivity to fine-scale bends and maintains global consistency of the array shape. Both simulation and lake-trial experiments validate the effectiveness of the proposed method, reducing the array shape estimation error by more than 30% relative to representative existing methods. Moreover, by relying solely on the received acoustic data, the method lowers the dependence on auxiliary sensors and the associated system cost. Full article

(This article belongs to the Special Issue Advanced Research in Underwater Acoustic Signal Processing)

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24 pages, 3595 KB

Open AccessArticle

A Numerical Study on Resistance and Self-Propulsion Performance Evaluation and Propeller Design Under Wave Conditions for an 1800 TEU Container Vessel

by Soonhyun Lee, Kwang-Jun Paik, Sua Jeong and Jae-Hyeon An

J. Mar. Sci. Eng. 2026, 14(16), 1538; https://doi.org/10.3390/jmse14161538 - 19 Aug 2026

Viewed by 299

Abstract

The propulsion performance and propeller design of ships have traditionally been evaluated mainly under calm-water conditions. However, under actual sea conditions, waves can increase added resistance, change the stern wake distribution, reduce propulsive efficiency, and affect cavitation behavior. This study evaluates the propulsion [...] Read more.

The propulsion performance and propeller design of ships have traditionally been evaluated mainly under calm-water conditions. However, under actual sea conditions, waves can increase added resistance, change the stern wake distribution, reduce propulsive efficiency, and affect cavitation behavior. This study evaluates the propulsion performance and designs a propeller for an 1800 TEU container ship under regular wave conditions using computational fluid dynamics. Resistance and self-propulsion simulations are conducted for eleven wavelength ratios in the range of

0.5 \leq λ / L_{P P} \leq 2.0

, with a fixed wave steepness of

H / λ = 0.01

. The results show that the required power increases significantly in the resonance wavelength range because of the combined effects of added resistance, wake variation, and reduced propulsive efficiency. The Brake Horsepower (BHP) transfer function obtained from the regular wave simulations is combined with representative sea-state spectra using the spectral method to estimate the Daily Fuel Oil Consumption (DFOC) under actual operating sea states. The total long term DFOC is estimated as 37.084 t/day. For the propeller design, the wake distribution at the propeller plane is analyzed at

λ / L_{P P} = 1.1

, as a representative wave condition where the ship motion and propulsion performance variation become significant. The wake analysis shows that the instantaneous inflow changes considerably according to the wave phase, which can affect blade loading and cavitation. Based on this analysis, a new propeller geometry is designed with the cavitation performance as the primary consideration while also improving the propulsion performance. The designed propeller reduces the cavity volume over the selected wave phases and decreases the delivered power by approximately 2.1% in calm water and 3.4% in wave conditions. These results demonstrate the importance of considering wake variation and cavitation characteristics in practical propeller design under actual operating conditions. Full article

(This article belongs to the Special Issue Hydrodynamics of Marine Propulsion and Trends in Computational and Experimental Simulations)

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45 pages, 17297 KB

Open AccessArticle

A PPO-Based Air-Space Collaborative Monitoring Method for Maritime Search and Rescue

by Zhaoyan Liao, Zhiqiang Du, Hongyuan Zeng and Kai Liu

J. Mar. Sci. Eng. 2026, 14(16), 1537; https://doi.org/10.3390/jmse14161537 - 19 Aug 2026

Viewed by 343

Abstract

Large-scale maritime activity, persistent shipping incidents, and complex marine environments continue to place substantial demands on maritime search and rescue (MSAR). Current MSAR systems do not fully capitalize on the complementary strengths of unmanned aerial vehicles (UAVs) and satellites for collaborative tracking and [...] Read more.

Large-scale maritime activity, persistent shipping incidents, and complex marine environments continue to place substantial demands on maritime search and rescue (MSAR). Current MSAR systems do not fully capitalize on the complementary strengths of unmanned aerial vehicles (UAVs) and satellites for collaborative tracking and rescue support. Existing air-space collaboration technologies suffer from two critical limitations: (1) rigid processes, including fixed task allocation, pre-determined path planning without real-time environmental adaptation, and isolated satellite–UAV decision-making, and (2) long task completion cycles, mainly because many methods are adapted to wide-area, long-duration military tracking scenarios. They therefore provide limited support for the dynamic flexibility required in MSAR. This study proposes a Proximal Policy Optimization (PPO)-based air-space collaborative tracking method for maritime moving targets to address these shortcomings and enhance air-space cooperation in MSAR operations. The core implementation of the method includes: (1) integration of target drift forecasting, satellite orbit prediction, UAV task allocation, and path planning into a unified reinforcement learning framework to reduce isolated single-platform decision-making; (2) the adoption of PPO to generate dynamic and flexible air-space collaborative tracking strategies that adjust satellite observation angles and scanning ranges, as well as UAV altitude, speed, and heading according to real-time target, environmental, and platform states; and (3) the design of a multi-dimensional reward function that balances target proximity, energy efficiency, coverage overlap, and inter-platform cooperation to guide strategy optimization. Simulation experiments include system-feasibility verification, baseline-controller comparison, PPO hyperparameter screening, and cross-scenario evaluation. Under idealized communication and payload-matching assumptions, the method enables coordinated tracking of maritime moving targets in simulated MSAR scenarios. In the standardized evaluation, PPO achieved an 11.9% higher mean evaluation episode return, 11.2% lower aggregate UAV energy consumption, and a 9.92-percentage-point greater endurance margin than DDPG. Hyperparameter screening compared candidate learning rates, discount factors, and training budgets, informing the PPO configuration for the subsequent six-scenario evaluation. Across the six controlled scenarios, rewards stabilized after approximately 1400 steps, while action magnitudes varied among regions. These results indicate that the proposed method has potential to enhance air-space collaborative tracking for MSAR decision support. Full article

(This article belongs to the Section Ocean Engineering)

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23 pages, 22631 KB

Open AccessArticle

Experimental and Numerical Study on Dynamic Response of PVC Foam Sandwich Beams Under Ice Impact

by Kailing Guo, Juncheng Chen, Wei Cai, Shuo Zhou and Mengying Mu

J. Mar. Sci. Eng. 2026, 14(16), 1536; https://doi.org/10.3390/jmse14161536 - 19 Aug 2026

Viewed by 282

Abstract

This paper mainly investigates the ice-impact resistance of PVC foam sandwich beams for polar ship protective structures through low-velocity impact experiments and nonlinear finite element simulations. An experimentally validated elastic–plastic coupled model, accounting for ice crushing and large structural deformation, was used to [...] Read more.

This paper mainly investigates the ice-impact resistance of PVC foam sandwich beams for polar ship protective structures through low-velocity impact experiments and nonlinear finite element simulations. An experimentally validated elastic–plastic coupled model, accounting for ice crushing and large structural deformation, was used to examine the effects of core density and face-sheet thickness distribution on the ice-impact response of sandwich beams. Results show that the upper face sheet undergoes local indentation and global bending, the lower face sheet mainly bends globally, and the foam core exhibits local compression and overall bending, while compressive deformation accompanied by ice crushing and spalling occurs at the front part of the ice impactor. Moreover, the effective structural stiffness decreased during plastic loading as local indentation and core compression developed, whereas the unloading stiffness was higher than the effective stiffness during plastic loading. Energy dissipation primarily comes from ice crushing, face-sheet plasticity, and core compression. Increasing core density reduces deflection and core compression but increases peak force. Among the three face-sheet configurations examined at a constant total thickness, the configuration with a thinner upper face sheet and a thicker lower face sheet produced a smaller final deformation of the lower face sheet. This study provides a useful reference for ice-resistant design of sandwich structures in polar ships. Full article

(This article belongs to the Section Ocean Engineering)

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22 pages, 6691 KB

Open AccessArticle

Ship-DiffDet: A Lightweight Diffusion Model for Small-Object Ship Detection

by Yanfeng Gong, Jing Huang, Daiyong Zhang and Jinlu Sheng

J. Mar. Sci. Eng. 2026, 14(16), 1535; https://doi.org/10.3390/jmse14161535 - 19 Aug 2026

Viewed by 307

Abstract

Ship detection over long distances is crucial for the visual perception of intelligent ships. AI techniques, particularly machine learning and deep learning, have achieved a series of breakthroughs in this field. However, due to the limited pixels of ships over long distances, such [...] Read more.

Ship detection over long distances is crucial for the visual perception of intelligent ships. AI techniques, particularly machine learning and deep learning, have achieved a series of breakthroughs in this field. However, due to the limited pixels of ships over long distances, such objects often suffer from weak feature representation and are susceptible to interference in complex environments. To address these challenges, this paper proposes an improved architecture named Ship-DiffDet, based on DiffusionDet. First, we redesign the backbone feature extraction network and propose IDC-Net, which utilizes inception depthwise convolution to enhance feature extraction efficiency while reducing computational complexity. Second, to tackle the difficulty of effectively extracting features from small objects, we design a Hybrid Pooling Attention-enhanced Feature Pyramid Network. By incorporating a hybrid pooling attention mechanism, it strengthens multi-scale feature fusion, thereby improving the performance of the detection heads. Furthermore, we introduce a multi-order gated aggregation mechanism into the dynamic detection head to optimize dynamic convolution and further compress the model’s parameter count. Experimental results demonstrate our method achieves an effective balance between detection accuracy and computational efficiency. On our custom-built small-object ship dataset, the proposed method improves AP₅₀ by 1.7% over the baseline while reducing the parameter and FLOPs counts by 48.8% and 22%, respectively. Full article

(This article belongs to the Special Issue AI-Driven Optimization of Ship Performance and Navigation Safety)

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25 pages, 3860 KB

Open AccessArticle

Distributional Shifts and Future Offshore Wind Energy Droughts Across the Mediterranean Basin

by Burak Aydoğan, Mehdi Aghajan Dastjerdi, Berna Ayat and Fulya Islek

J. Mar. Sci. Eng. 2026, 14(16), 1534; https://doi.org/10.3390/jmse14161534 - 19 Aug 2026

Viewed by 369

Abstract

Offshore wind energy droughts are quantified at eight strategic sites using a Standardized Renewable Energy Production Index referenced to an 86-year-ERA5 baseline. Events are extracted via multi-threshold run theory and projected to 2100 using bias-corrected CMIP6 models under SSP2-4.5 and SSP5-8.5. Drought climatology [...] Read more.

Offshore wind energy droughts are quantified at eight strategic sites using a Standardized Renewable Energy Production Index referenced to an 86-year-ERA5 baseline. Events are extracted via multi-threshold run theory and projected to 2100 using bias-corrected CMIP6 models under SSP2-4.5 and SSP5-8.5. Drought climatology shows that mean drought duration and severity exhibit spatial heterogeneity, peaking in the Aegean–Cretan sector. Under future warming, a robust, false-discovery-rate-controlled intensification is predominantly concentrated in the central–western basin, associated with structural shifts toward weaker, heavy-tailed wind distributions. The Sicily Channel and Gulf of Lion emerge as hotspots for drought intensification, exhibiting consistent annual total duration increases of up to 20% and 15%, respectively, under the SSP5-8.5 scenario. Winter droughts across the basin are associated with a complex interplay of the AO, NAO, EA, and EA/WR teleconnections, alongside a pronounced winter MOI influence in the west. Summer droughts in the Aegean–Cretan sector are strongly coupled with the weakening of the MOI, reflecting the collapse of the basin-scale pressure gradient that sustains the Etesian winds. The central–western Mediterranean emerges as a key region for adaptive, long-duration energy storage planning, whereas the climatology of the eastern basin remains a defensible baseline for future capacity design. Full article

(This article belongs to the Section Marine Energy)

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32 pages, 1617 KB

Open AccessReview

Towards Human Factors Evaluation of Interactions with Maritime Autonomous Surface Ships Using Full Mission Bridge Simulators: The Conventional Officer’s Perspective

by Pieter Maes, Elspeth McMahon, Doreen Jirak, Dirk van Rooy, Werner Jacobs, Rowan Van Schaeren, Edwin Van Hassel and Stijn Verwulgen

J. Mar. Sci. Eng. 2026, 14(16), 1533; https://doi.org/10.3390/jmse14161533 - 19 Aug 2026

Viewed by 770

Abstract

Research and development of Maritime Autonomous Surface Ships (MASS) has surged in recent years. However, questions remain regarding the safety of interactions between MASS and conventionally crewed ships in mixed-traffic environments, particularly during collision avoidance. Although the critical role of MASS technology is [...] Read more.

Research and development of Maritime Autonomous Surface Ships (MASS) has surged in recent years. However, questions remain regarding the safety of interactions between MASS and conventionally crewed ships in mixed-traffic environments, particularly during collision avoidance. Although the critical role of MASS technology is widely recognised, few studies have explored how these interactions may affect the behaviour of the conventional ship’s Officer of the Watch (OOW). The primary aim of this paper is to explore the challenges and complexities of mixed-traffic interaction from the perspective of the conventional OOW as an active participant in collision avoidance. A collision-avoidance framework is presented as an analytical lens linking situational awareness, motion prediction, mental models, conflict detection, conflict resolution, and manoeuvre execution. This framework is used to examine challenges related to communication, COLREG interpretation, uncertainty surrounding MASS capabilities and operations, knowledge and training, and trust. We argue that these factors may influence how OOWs interpret MASS behaviour and determine whether, when, and how to intervene. To address this research gap, key research questions are formulated, and a scenario-driven methodological approach using Full Mission Bridge Simulators (FMBS) is proposed to investigate changes in OOW behaviour and decision-making during mixed-traffic encounters. Full article

(This article belongs to the Special Issue Recent Advances in Maritime Safety and Ship Collision Avoidance (2nd Edition))

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22 pages, 4913 KB

Open AccessArticle

UADet: Redefining Marine Debris Detection in Degraded Underwater Scenes with Adaptive Feature and Boundary Refinement

by Yingying Wang, Jingsi Liu, Wenru Zhang and Qi Zhang

J. Mar. Sci. Eng. 2026, 14(16), 1532; https://doi.org/10.3390/jmse14161532 - 18 Aug 2026

Viewed by 318

Abstract

Underwater marine debris detection is important for marine environmental monitoring, robotic inspection, and debris removal. However, reliable detection remains challenging because underwater images often suffer from low illumination, color distortion, turbidity, cluttered backgrounds, and weak boundaries. These factors reduce feature reliability and hinder [...] Read more.

Underwater marine debris detection is important for marine environmental monitoring, robotic inspection, and debris removal. However, reliable detection remains challenging because underwater images often suffer from low illumination, color distortion, turbidity, cluttered backgrounds, and weak boundaries. These factors reduce feature reliability and hinder accurate localization, especially for small, occluded, or low-visibility debris. To address these challenges, this paper proposes UADet, an adaptive detector for marine debris detection in degraded underwater scenes. UADet integrates two complementary components: Underwater Degradation-aware Feature Modulation (UDFM) and Visibility-aware Boundary Distribution Refinement (VBDR). UDFM extracts lightweight image-level degradation cues and modulates multi-scale features to improve robustness under varying underwater conditions. VBDR incorporates object scale and an appearance-based proxy for local visual difficulty into boundary distribution learning and matching cost, providing adaptive localization supervision for small objects and objects with weak visual evidence. Experiments are conducted on TrashCan and J-Litter, and UADet is compared with representative real-time detectors, including YOLOv8s, YOLOv10s, YOLOv11s, and RT-DETR. The results show that UADet achieves the best performance on both datasets, with 72.74% mAP@0.5, 81.36% precision, and 69.36% recall on TrashCan, and 48.02% mAP@0.5, 70.13% precision, and 55.61% recall on J-Litter. Compared with the strongest baseline, UADet improves mAP@0.5 by 3.12 percentage points on TrashCan and 4.83 percentage points on J-Litter. Ablation and qualitative analyses demonstrate that UDFM and VBDR provide complementary improvements. These results indicate that modeling underwater degradation and boundary uncertainty improves the robustness and reliability of marine debris detection in challenging underwater environments. Full article

(This article belongs to the Section Ocean Engineering)

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58 pages, 6493 KB

Open AccessReview

A Comprehensive Review of Oil Spill Fate Models and Operational Tools: Capabilities and Applicability to the Caspian Sea

by Aziz Kudaikulov, Tangnur Amanzholov, Abdurashid Aliuly, Abzal Seitov, Bakytzhan Assilbekov, Alibek Kuljabekov, Spartak Shabilov, Dinmukhambet Baimbetov, Samal Syrlybekkyzy and Aidarkhan Kaltayev

J. Mar. Sci. Eng. 2026, 14(16), 1531; https://doi.org/10.3390/jmse14161531 - 18 Aug 2026

Viewed by 324

Abstract

The Caspian Sea’s unique environment and intense hydrocarbon extraction make it a high-risk, understudied region for oil spill modelling. This review assesses the physical, chemical, and biological processes governing oil spill transport and fate, and evaluates the principal numerical tools available for the [...] Read more.

The Caspian Sea’s unique environment and intense hydrocarbon extraction make it a high-risk, understudied region for oil spill modelling. This review assesses the physical, chemical, and biological processes governing oil spill transport and fate, and evaluates the principal numerical tools available for the Caspian Sea context. The weathering processes are reviewed from foundational formulations to operational implementations. Key research challenges identified include the absence of photo-oxidation from operational models, limited laboratory data for Caspian crude oil types, and simplified biodegradation parameterizations. Hydrodynamic forcing uncertainty, arising from the lack of a dedicated operational ocean model, remains the dominant source of trajectory forecast error. Seven operational oil spill modelling tools and the ROMS hydrodynamic platform are reviewed. Only OSCAR and MIKE 21 have documented applications to the Caspian Sea, representing a significant regional gap. ROMS is identified as the most suitable hydrodynamic platform for future operational forecasting. Finally, the integration of machine learning and deep learning methods, including neural network trajectory prediction and SAR detection, is discussed as a promising frontier for improving forecast accuracy in this data-sparse environment. Full article

(This article belongs to the Section Ocean Engineering)

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34 pages, 10115 KB

Open AccessArticle

Preliminary Exploration of Resistance, Wave-Making and Pressure Distribution of Amphibious Assault Vehicle Clusters in Different Formations

by Sixing Guo, Yutao Tian, Yuting Li, Zehan Chen, Kexin Xie, Yixuan Zeng and Dapeng Zhang

J. Mar. Sci. Eng. 2026, 14(16), 1530; https://doi.org/10.3390/jmse14161530 - 18 Aug 2026

Viewed by 220

Abstract

Amphibious assault vehicles serve as core equipment for coastal defense and amphibious operations worldwide, with irreplaceable strategic value. Featuring outstanding comprehensive performance, modern amphibious assault vehicles can maintain stable navigation under Sea States 3–4 and adapt to complex nearshore hydrological environments, emerging as [...] Read more.

Amphibious assault vehicles serve as core equipment for coastal defense and amphibious operations worldwide, with irreplaceable strategic value. Featuring outstanding comprehensive performance, modern amphibious assault vehicles can maintain stable navigation under Sea States 3–4 and adapt to complex nearshore hydrological environments, emerging as the primary platform for mechanized landing operations of the Marine Corps. Cluster navigation is an inevitable tactical form in the operational application of amphibious assault vehicles. When multiple vehicles sail in formation, the wave-making and water pressure effects induced by individual vehicles generate prominent wave interference drag within the formation, which significantly impacts the overall navigation efficiency and stability. Based on the nearshore combat background of amphibious landing, this paper investigates different formation layouts of amphibious assault vehicle clusters to determine the optimal configuration for group navigation. First, a numerical simulation and a physical experiment are combined; a certain type of amphibious assault vehicle is taken as the prototype for 3D geometric modeling via SOLIDWORKS. Then, adopting the CFD numerical simulation method, with navigation speed and optimal inter-vehicle spacing fixed, variables including formation layout and number of vehicles are controlled to simulate the flow field characteristics and total resistance of different cluster formations in calm water. Meanwhile, 3D printing technology is applied to manufacture scaled-down models for towing tank tests. The experimental results are in good agreement with numerical simulations, revealing the fundamental hydrodynamic laws of formation navigation. Under optimal inter-vehicle spacing, the longitudinal tandem formation achieves the best drag-reduction effect, while the double-column staggered formation (diamond/V formation) can effectively suppress wave interference drag and improve the overall hydrodynamic performance and tactical coordination. The research provides a solid theoretical basis and data support for optimizing formation sailing strategies, enhancing cluster navigation stability and safety, and improving maritime maneuver efficiency. It is also of universal reference value for the tactical deployment of amphibious combat equipment globally. Full article

(This article belongs to the Special Issue Coupled Hydrodynamics and Innovative Mooring Systems for Offshore Floating Structures)

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28 pages, 17034 KB

Open AccessArticle

Ship Sub-Trajectories Clustering: A Comparative Study on DBSCAN and Spectral Clustering with Dimensionality Reduction

by Golnoosh Toosi, Xing Wu and Victor A. Zaloom

J. Mar. Sci. Eng. 2026, 14(16), 1529; https://doi.org/10.3390/jmse14161529 - 18 Aug 2026

Viewed by 318

Abstract

Maritime transportation, handling over 80% of global trade, is critical to the world economy. Automatic Identification System (AIS) data provides extensive static and dynamic information of vessels, enabling trajectory reconstruction and vessel behavior analysis. Recently, trajectory clustering has become a key method for [...] Read more.

Maritime transportation, handling over 80% of global trade, is critical to the world economy. Automatic Identification System (AIS) data provides extensive static and dynamic information of vessels, enabling trajectory reconstruction and vessel behavior analysis. Recently, trajectory clustering has become a key method for analyzing maritime traffic, offering valuable insights to improve traffic management and operational efficiency. This research aims to investigate how to effectively cluster ship sub-trajectories derived from AIS data by comparing two machine learning clustering algorithms, Density-based spatial clustering of applications with noise (DBSCAN) and spectral clustering, with a focus on improving data quality, extracting key dynamic features, and evaluating the effect of dimensionality reduction on clustering performance. Clustering sub-trajectories can help reveal localized navigation patterns and movement behaviors. The study implemented the proposed methods for tankers and cargo ships (with AIS data from 2022) in a Y-shaped channel in the Sabine-Neches Waterway (SNWW) in Southeast Texas, where the busiest docks are located. Finally, clustering performance was evaluated with the silhouette coefficient (SC), Davies–Bouldin Index (DBI), and Joint Performance Index (JPI), respectively. Experimental results show that DBSCAN effectively identifies dense, overlapping trajectory clusters and labels noise, while the spectral clustering algorithm detects subtle behavioral differences but struggles with less cohesive clusters, and does not explicitly handle noise. Full article

(This article belongs to the Special Issue Autonomous Ship and Harbor Maneuvering: Modeling and Control)

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25 pages, 111771 KB

Open AccessArticle

Wind-Resistance Stability Analysis of a Magnetic Adhesion Wall-Climbing Obstacle-Crossing Robot for Offshore Wind Turbines

by Jun Liu, Shaojie Jing, Yongsheng Yang and Shiteng Yang

J. Mar. Sci. Eng. 2026, 14(16), 1528; https://doi.org/10.3390/jmse14161528 - 18 Aug 2026

Viewed by 275

Abstract

To address the challenges of adsorption instability and obstacle-crossing difficulties faced by wall-climbing robots in the harsh operation and maintenance (O&M) environment of offshore wind turbine (OWT) towers, this paper presents the design of a magnetic-adhesive wall-climbing robot with a planetary-gear configuration and [...] Read more.

To address the challenges of adsorption instability and obstacle-crossing difficulties faced by wall-climbing robots in the harsh operation and maintenance (O&M) environment of offshore wind turbine (OWT) towers, this paper presents the design of a magnetic-adhesive wall-climbing robot with a planetary-gear configuration and investigates its wind resistance stability. First, the magnetic circuit layout is optimized through finite element analysis, revealing that the F-16 continuous planetary configuration (16 poles) effectively suppresses magnetic flux leakage and forms an integrated magnetic pad, maintaining adsorption force at a large air gap of 20 mm, thereby enhancing magnetic robustness during obstacle crossing and making it the optimal choice for high-load offshore conditions. Second, an unsteady flow field model based on the Kaimal turbulence spectrum is constructed to analyze aerodynamic loads. Fluid–structure interaction (FSI) simulations demonstrate that at a height of 30 m, the turbulence integral scale matches the robot dimensions, and combined with the Venturi effect of gap jet flow, this leads to peak turbulence intensity and pitching moment, creating a hazardous, pronounced aerodynamic amplification condition. Finally, an anti-slip stability model is established, revealing that vertical wall climbing represents the critical loading scenario; the magnetic adhesion system must deliver a total adsorption force of no less than 1000 N to resist a 35 m/s wind speed under low-friction conditions, providing a quantitative design basis for anti-wind safety. This study integrates magnetic circuit optimization, turbulence-resolved aerodynamics, and macroscopic anti-slip mechanics, offering theoretical support and engineering guidance for the safe deployment of intelligent O&M equipment for offshore wind power. Bench-scale measurements of magnetic adhesion force, friction coefficient, and translation force fluctuation support the exponential-decay magnetic model and the multi-wheel phase-interleaving concept; however, the current 4 × 16-pole prototype delivers ~627 N at the 2 mm working gap, below the 1000 N design target. The design methodology is therefore validated, while the current physical configuration requires further iteration of the working gap or magnet grade before it can be considered operationally adequate. Full article

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J. Mar. Sci. Eng., Volume 14, Issue 16 (August-2 2026) – 108 articles

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