In recent years, marine pilotage accidents occurring on a worldwide basis as a result of human error have not been ceased to transpire, despite advances in technology and a significant set of international conventions, regulations, and recommendations to reduce them. This paper aims to investigate the effect of human factors on the safety of maritime pilotage operations. The human factors that affect the operators who are performing ships’ berthing operations have also been examined in detail. In this study, in order to determine the causes of human-related errors occurred in maritime pilotage accidents, a comprehensive literature review is carried out, and a considerable number of real past case examples and an analysis of the maritime accident investigation reports regarding pilotage operations events that occurred between 1995 and 2015 have been reviewed. To validate the identified human-related risk factors (HCFs) and explore other contributory factors, survey questionnaires and semi-structured interviews with domain experts have been conducted. A structural hierarchy diagram for the identified risk factors (HCFs) has been developed and validated through experienced experts belonging to the maritime sector. A questionnaire for pair-wise comparison is carried out and analysed using the analytic hierarchy process (AHP) approach to evaluate the weight and rank the importance of the identified human causal factors. The findings of this study will benefit the maritime industry, by identifying a new database on causal factors that are contributing to the occurrence of maritime pilotage disasters. The database can be used as a stand-alone reference or help implement effective risk reduction strategies to reduce the human error, that might occur during pilotage operations.

This paper proposes a semi-empirical model to predict a ship’s speed loss at arbitrary wave heading. In the model, the formulas that estimate a ship’s added resistance due to waves attacking from different heading angles have been further developed. A correction factor is proposed to consider the nonlinear effect due to large waves in power estimation. The formulas are developed and verified by model tests of 5 ships in regular waves with various heading angles. The full-scale measurements from three different types of ships, i.e., a PCTC, a container ship, and a chemical tanker, are used to validate the proposed model for speed loss prediction in irregular waves. The effect of the improved model for speed loss prediction on a ship’s voyage optimization is also investigated. The results indicate that a ship’s voyage optimization solutions can be significantly affected by the prediction accuracy of speed loss caused by waves.

The wind-assisted propulsion system is becoming one of the most popular and efficient ways to reduce both fuel consumption and carbon dioxide emission from the ships. In this study, several analyses have been carried out on a model of bulk carrier fitted with five rigid sails with a 180° rotating mechanism for maximum usage of wind power and a telescopic reefing mechanism for folding it during berthing. The stability of the ship has been verified through the calculations of initial stability, static stability, and dynamic stability through the fulfillment of the weather criterion using MAXSURF software. The structural analysis of the sail was carried out in ANSYS static structural module. Several flow simulations were carried out in ANSYS fluent module to predict the thrusts produced by the sails at different apparent wind angles, which would in turn reduce the thrust required from the propeller. In this way, the brake horse powers required for different sail arrangements were analyzed to find out a guideline for this wind propulsion system to generate better powering performances. To consider drift and yaw effect on propulsion system, an MMG mathematical model–based simulation was carried out for different drift angles of motion of the ship considering hard sail–based wind loads. Through these analyses, it has been found out that the hard sail–based wind-assisted propulsion system in some cases have produced a reduction of more than 30% brake power in straight ahead motion and around 20% reduction in case of drifting ships compared to the model having no sails.

Large size vessels sailing in continuous level ice and broken ice of high concentration are mostly assisted by icebreakers. This is done in order to provide for fast transportation through the North Sea Route and safe operation in extreme ice conditions. Currently, new large size gas and oil carriers and container ships are being designed and built with beams much greater than the beams of existing icebreakers. At the same time, no mathematical description exists for the breaking mechanism of ice channel edges, when such vessels move under icebreaker escort. This paper suggests a simple method for assessment of the ice resistance in the case of a large ship running in an icebreaker channel; the method is based on modification of well-known semi-empirical methods for calculation of the ice resistance to ships in level and broken ice. The main feature of the proposed calculation scheme consists in that different methods are applied to estimate the ice resistance in broken ice and due to breaking of level ice edges. The combination of these methods gives a deliverable ice resistance of a large size vessel moving under icebreaker assistance in a newly made ice channel. In general, proposed method allows to define the speed of a carrier moving in an ice channel behind a modern linear icebreaker and could be applied at the ship design stage and during development of the marine transportation system. The paper also discusses the ways for further refinement of the assessment procedure suggested.

This paper presented the results of an experimental investigation into the resistance performance of a wave-piercing trimaran with three alternative side hull forms, including asymmetric inboard, asymmetric outboard, and symmetric at various stagger/separation positions. Model tests were carried out at the National Iranian Marine Laboratory (NIMALA) towing tank using a scale model of a trimaran at the Froude numbers from 0.225 to 0.60. Results showed that by moving the side hulls to the forward of the main hull transom, the total resistance coefficient of trimaran decreased. Findings, furthermore, demonstrated that the symmetry shape of the side hull had the best performance on total resistance among three side hull forms. Results of this study are useful for selecting the side hull configuration from the resistance viewpoint.

This paper proposes and analyzes a novel heating coil bundle with the tubes arranged in a multi-level manner. The bundle generates a heated cargo large-scale circulation that enables a superposition of the circulation-driven forced convection on the buoyancy-driven natural convection, providing a more efficient mixed convection heat transfer mechanism. A simulation-based comparison of the proposed design and the conventional design is provided. The test case comprising an actual tank heating of an RMH 45 residual fuel oil by an 8-bar steam is simulated by a finite volume method and an OpenFOAM computational fluid dynamics software. The simulation results reveal that a 47.1% higher average heat transfer coefficient may be achieved, allowing a 32.0% reduction of the required heating coil area.

The paper focuses on the assessment of the hull girder ultimate strength, combined with random pitting corrosion wastage, by the incremental-iterative method. After a brief review about the state of art, the local ultimate strength of pitted platings under uniaxial compression is preliminarily outlined and subsequently a closed-form design formula is endorsed in the Rule incremental-iterative method, to account for pitting corrosion wastage in the hull girder ultimate strength check. The ISSC bulk carrier is assumed as reference ship in a benchmark study, devoted to test the effectiveness of the incremental-iterative method, by a comparative analysis with a set of FE simulations, performed by Ansys Mechanical APDL. Four reference cases, with different locations of pitting corrosion wastage, are investigated focusing on nine combinations of pitting and corrosion intensity degrees. Finally, a comparative analysis between the hull girder ultimate strength, combined with pitting corrosion wastage, and the relevant values, complying with the Rule net scantling approach, is performed. Based on current results, the modified incremental-iterative method allows efficiently assessing the hull girder ultimate strength, combined with pitting corrosion wastage, so revealing useful both in the design process of new vessels and in the structural health monitoring of aged ships.

This study investigates the interaction and influence of surface cracks on the spherical pressure hull of a deep-sea manned submersible. The finite element model of the spherical hull is established, and a semi-elliptical surface crack is inserted in the welding toe of the spherical hull as the main crack. Considering the combined effect of external uniform pressure and welding residual stress at the weld toe, the stress intensity factor (SIF) is obtained based on the M-integral method. Inserting disturbing cracks at different positions on the spherical hull surface, the interaction and influence between multi-cracks are revealed by numerical calculation. The results show that the existence of the disturbing crack has a great influence on the stress intensity factor of the main crack, and the influence is different with the different location of disturbing crack. The study of the interaction of multiple cracks under different interference factors and the influence of disturbing cracks on the main crack can provide some reference for future engineering applications.

Command governor–based adaptive control (CGAC) is a recent control strategy that has been explored as a possible candidate for the challenging task of precise maneuvering of unmanned underwater vehicles (UUVs) with parameter variations. CGAC is derived from standard model reference adaptive control (MRAC) by adding a command governor that guarantees acceptable transient performance without compromising stability and a command filter that improves the robustness against noise and time delay. Although simulation and experimental studies have shown substantial overall performance improvements of CGAC over MRAC for UUVs, it has also shown that the command filter leads to a marked reduction in initial tracking performance of CGAC. As a solution, this paper proposes the replacement of the command filter by a weight filter to improve the initial tracking performance without compromising robustness and the addition of a closed-loop state predictor to further improve the overall tracking performance. The new modified CGAC (M-CGAC) has been experimentally validated and the results indicate that it successfully mitigates the initial tracking performance reduction, significantly improves the overall tracking performance, uses less control force, and increases the robustness to noise and time delay. Thus, M-CGAC is a viable adaptive control algorithm for current and future UUV applications.

The work is a case study of a cruise ship supplied by liquefied natural gas (LNG) and equipped with a solid oxide fuel cell (SOFC). It is supposed that a 20 MW SOFC plant is installed on-board to supply hotel loads and assisting three dual-fuel (DF) diesel/LNG generator sets. LNG consumption and emissions are estimated both for the SOFC plant and DF generator sets. It results that the use of LNG-SOFC plant in comparison to DF generator sets allows to limit significantly the SO_x, CO, NO_x, PM emissions and to reduce the emission of CO₂ by about 11%. A prediction of the weight and volume of the SOFC plant is conducted and a preliminary modification of the general arrangement of the cruise ship is suggested, according to the latest international rules. It results that the SOFC plant is heavier and occupies more volume on board than a DF gen-set; nevertheless, these features do not affect the floating and the stability of the cruise ship.

In this study, a model is developed to simulate the dynamics of an internal combustion engine, and it is calibrated and validated against reliable experimental data, making it a tool that can effectively be adopted to conduct emission predictions. In this work, the Ricardo WAVE software is applied to the simulation of a particular marine diesel engine, a four-stroke engine used in the maritime field. Results from the bench tests are used for the calibration of the model. Finally, the calibration of the model and its validation with full-scale data measured at sea are presented. The prediction includes not only the classic engine operating parameters for a comparison with surveys but also an estimate of nitrogen oxide emissions, which are compared with similar results obtained with emission factors. The calibration of the model made it possible to obtain an overlap between the simulation results and real data with an average error of approximately 7% on power, torque, and consumption. The model provides encouraging results, suggesting further applications, such as in the study on transient conditions, coupling of the engine model with the ship model for a complete simulation of the operating conditions, and optimization studies on consumption and emissions. The availability of the emission data during the sea trial and validated simulation results are the strengths and novelties of this work.

The flow noise associated with sinusoidal vertical motion of a sonobuoy restrains its working performance. In practice, a suspension system consisting of elastic suspension cable and isolation mass is adopted to isolate the hydrophone from large vertical motions of the buoy on the ocean surface. In the present study, a theoretical model of vertical motion based on the sonobuoy suspension system was proposed. The vertical motion velocity response of the hydrophone of a sonobuoy can be obtained by solving the theoretical model with Runge-Kutta algorithm. The flow noise of the hydrophone at this response motion velocity was predicted using a hybrid computational fluid dynamics (CFD)-Ffowcs Williams-Hawkings (FW-H) technique. The simulation results revealed that adding the elastic suspension cable with an appropriate elastic constant and counterweight with an appropriate mass have a good effect on reducing the flow noise caused by the sonobuoy vertical motion. The validation of this hybrid computational method used for reliable prediction of flow noise was also carried out on the basis of experimental data and empirical formula. The finds of this study can supply the deep understandings of the relationships between flow noise reduction and sonobuoy optimization.

The exploitation of wind energy is rapidly evolving and is manifested in the ever-expanding global network of offshore wind energy farms. For the Small Island Developing States of the Caribbean Sea (CS), harnessing this mature technology is an important first step in the transition away from fossil fuels. This paper uses buoy and satellite observations of surface wind speed in the CS to estimate wind energy resources over the 2009–2019 11-year period and initiates hour-ahead forecasting using the long short-term memory (LSTM) network. Observations of wind power density (WPD) at the 100-m height showed a mean of approximately 1000 W/m² in the Colombia Basin, though this value decreases radially to 600–800 W/m² in the central CS to a minimum of approximately 250 W/m² at its borders in the Venezuela Basin. The Caribbean Low-Level Jet (CLLJ) is also responsible for the waxing and waning of surface wind speed and as such, resource stability, though stable as estimated through monthly and seasonal coefficients of variation, is naturally governed by CLLJ activity. Using a commercially available offshore wind turbine, wind energy generation at four locations in the CS is estimated. Electricity production is greatest and most stable in the central CS than at either its eastern or western borders. Wind speed forecasts are also found to be more accurate at this location, and though technology currently restricts offshore wind turbines to shallow water, outward migration to and colonization of deeper water is an attractive option for energy exploitation.

Water transportation today has become increasingly busy because of economic globalization. In order to solve the problem of inaccurate port traffic flow prediction, this paper proposes an algorithm based on gated recurrent units (GRUs) and Markov residual correction to pass a fixed cross-section. To analyze the traffic flow of ships, the statistical method of ship traffic flow based on the automatic identification system (AIS) is introduced. And a model is put forward for predicting the ship flow. According to the basic principle of cyclic neural networks, the law of ship traffic flow in the channel is explored in the time series. Experiments have been performed using a large number of AIS data in the waters near Xiazhimen in Zhoushan, Ningbo, and the results show that the accuracy of the GRU-Markov algorithm is higher than that of other algorithms, proving the practicability and effectiveness of this method in ship flow prediction.