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The uncertainty in estimating the wave spectrum from the records of wave elevation by heave–pitch–roll buoys is studied, considering the effects of the estimation method and the spectral resolution adopted in the process. This investigation utilizes measurements from a wave buoy moored in deep water in the South Atlantic Ocean. First, the spectra are computed using the autocorrelation function and the direct Fourier method. Second, the spectral resolution is tested in terms of degrees of freedom. The degrees of freedom are varied, and the resulting spectra and integrated parameters are computed, showing significant variability. A simple and robust methodology for determining the wave spectrum is suggested, which involves calculating the average energy density in each frequency band. The results of this methodology reduce the variability of the estimated parameters, improving overall accuracy while preserving frequency resolution, which is crucial in complex sea states. Additionally, to demonstrate the feasibility of the implemented approach, the final spectrum is fitted using an empirical model ideal for that type of spectrum. Finally, the performance and the goodness of the fit process for the final averaged curve are checked by widely used statistical metrics, such as R2 = 0.97 and root mean square error = 0.49.

The reporting system for fishing vessel and crew casualties in Peru needs a disruptive change in order to know what the risks in terms of marine safety are, who should manage them, and how they should be managed. According to a technical review on accidents recorded by the Peruvian Direction of Captaincies and Coast Guards (DICAPI), it is evident there is a need to process the available information on casualties of fishing vessels and crew in the fishing industry since this information is not easy to analyze. Nevertheless, this paper provides the casualties reported between 2004 and 2010, and from 2013 to 2020. In order to understand the research endeavors and trends surrounding the safety of fishing vessels, a systematic review using VOSviewer was performed. After a deep analysis and study of the information available in Peru, as well as reports and regulations from the International Maritime Organization (IMO), Food and Agriculture Organization (FAO), International Convention for the Safety of Life at Sea (SOLAS), and the recent advances available in the scientific literature on the safety of fishing vessels and crew casualties around the world, this paper presents some proposals regarding the current Peruvian scenario that are expected to be considered in new regulations.

The Andalusian Agency of Energy has identified three areas of major interest for harnessing wave energy, in their plan of “Marine Energy and Energy Resources of Andalusia”. One of these areas is located on the Atlantic coast, the bay of Cádiz. Considering this initial interest, the objective of this work is to carry out an evaluation of the performance provided by various technologies of wave energy conversion in the bay of Cádiz. The data for the wave climate in the target area are obtained from the Spanish Agency Puertos del Estado. Diagrams for bivariate distributions of the sea states occurrences, defined by the significant wave height and the energy period, are shown. On this basis, the output of nine different technologies for the conversion of wave energy is assessed in the reference locations in the bay of Cádiz. According to the results obtained, it can be said that the bay of Cádiz is a suitable place for wave energy extraction.

Decision support systems (DSS) recently have been increasingly in use during ships operation. They require realistic input data regarding different aspects of navigation. To address the optimal weather routing of a ship, which is one of the most promising field of DSS application, it is necessary to accurately predict an actually attainable speed of a ship and corresponding fuel consumption at given loading conditions and predicted weather conditions. In this paper, authors present a combined calculation method to predict those values. First, a deterministic modeling is applied and then an artificial neural network (ANN) is structured and trained to quickly mimic the calculations. The sensitivity of the ANN to adopted settings is analyzed as well. The research results confirm a more than satisfactory quality of reproduction of speed and fuel consumption data as the ANN response meet the calculation results with high accuracy. The ANN-based approach, however, requires a significantly shorter time of execution. The directions of future research are outlined.

In this article, a direct neural network based adaptive backstepping control approach is proposed for a class of uncertain non-affine ship manoeuvring pure-feedback nonlinear systems. To carry out the backstepping design, the high fidelity 3 degrees of freedom Manoeuvring Modelling Group (MMG) model with external disturbances is transformed into the ship manoeuvring systems in non-affine pure-feedback form. Then, by combing the Implicit Function Theorem, Mean Value Theorem and dynamic surface control technique, the proposed approach is able to avoid completely the circularity problem and complexity growing problem exist in the adaptive neural network controller. During the controller design, the uncertain nonlinear functions are approximated by neural networks. Following this control approach, it is worth noting that the direct adaptive backstepping control for the high fidelity MMG model based ship manoeuvring nonlinear systems is achieved firstly, and the controller structure is simpler. Furthermore, it is shown via stability analysis that all signals in the closed-loop system are uniformly ultimately bounded. At last, two reference signals consist of a constant and a realistic performance requirement of ship are applied to simulation studies to illustrate the utility and merits of the proposed control scheme.

An analytical model of a current load’s interaction with a moored floating flexible structure based on the Timoshenko–Mindlin beam theory is developed under the assumption of small-amplitude wave theory and the structural response. Theoretical solutions on the displacement of the structure, reflection, and transmission coefficients are obtained by applying the matching technique along with the orthogonal model coupling relation. The results of the transmission coefficient and displacement amplitude are compared with the other calculations and experimental datasets available in the literature. The structural deflection and transmission coefficients are investigated via the hydroelastic response for wave–current loads along with design parameters. The comparison results showed that the present model result is supported by the numerical model’s results. This present analysis can provide further information for marine engineers to design floating flexible platforms in the marine environment.

This paper proposes an approach for identifying and characterizing shipping routes using information contained in Automatic Identification System messages broadcasted by ships and recorded by the coastal Vessel Traffic Service centre. The approach consists of using historical Automatic Identification System data to build a graph, where nodes are cells of a grid covering the geographical area being studied and the weights of directional edges are inversely related to ship movements between cells. Based on this graph, the Dijkstra algorithm is used to identify a potential safe route, assumed to be the most used route by ships between two locations. A second graph is created simultaneously, with the same nodes and edges, but with edge weights equal to the average speed of transitions between cells, thus allowing the determination of the average speed profile for any possible path within the graph. The proposed approach is applied to two scenarios: an approach to the port of Lisbon and the entry through the fairway to a RO-RO terminal in the port of Setubal in Portugal.

The influence of weather conditions on fuel consumption and CO2 emissions for a containership is assessed by calculating the total added resistance, for various sea-states and relative wave directions, through a time domain procedure. The present article extended a formerly published research presented during the IMAM2015 conference [1] providing a deeper insight of the methodology adopted furtherly discussing the results achieved. In particular, the present paper studies the impact of wind velocity and directionality on the ship speed and its relative importance when compared with the wave added resistance. Moreover, considering the most commonly sailed routes in the North Atlantic, the long-term rate of increment of fuel consumption and CO2 emissions is estimated comparing the resulting ship performance with the wave climate expected for these specific routes.

The work presents the identification and validation of the hydrodynamic coefficients for the surge, sway, and yaw motion. This is performed in two ways: using simulated data and free-running test data. The identification and validation with the simulation data are carried out using a 25° turning test and a 20°−20° zigzag manoeuvring test. For the free-running test data, two zigzag manoeuvres are used: 30°−30° zigzag for identification and 20°−20° zigzag for validation. A nonlinear manoeuvring model is proposed based on the standard Euler equations, and the hydrodynamic coefficients are computed using empirical equations. To obtain robust results, the truncated singular value decomposition is employed to diminish the multicollinearity and the parameter uncertainties due to noise. The validation is carried out by comparing the result of the measured values with the predictions obtained using the manoeuvring models. Finally, a sensitivity analysis for the simulation data is performed to understand the influence of the parameters in the manoeuvres.

This paper presents a comparison between different types of propellers operated in calm water to evaluate their performance behind hulls and in open-water conditions. A bulk carrier is chosen as a case study to perform the simulation and to evaluate the performance of several propeller series, namely the Wagengein B-series, Kaplan 19A, and MAU. Firstly, optimization procedures are performed by coupling a propeller design tool and a nonlinear optimizer to find the optimum design parameters of a fixed-pitch propeller. This optimization model aims to design the propeller behind the hull at the engine operating point with minimum fuel consumption and maximum propeller efficiency. The two main objectives of this study and the constraints are defined in a single fitness function to find the optimum values of the propeller geometry and the gearbox ratio. By considering the benefits of the single-objective over the multi-objective optimization problem, this model helps to find the optimum propeller for both defined objectives instead of only considering one of them, as in previous studies. Then, based on the optimized parameters, the propeller performance is calculated in open-water conditions. From the computed results, one can observe the importance of considering the hull–propulsor interaction in propeller selection.

The study presents a methodology for floating wind farms site selection with a Canary Islands case study. The frame combines geographical information systems (GIS) and multiple criteria decision methods (MCDMs). First, the problematic areas for the installation of the turbines are identified through a GIS database application. This tool generates thematic layers representing exclusion criteria. Then, at the second stage of the study, available maritime locations are analyzed and ranked using the analytical hierarchy process (AHP), based on technical, economic, and environmental aspects. AHP’s technique guarantee the elimination of the judgment’s subjectivity. The study also compared the solutions of the AHP technique with other methods, such as Preference Ranking Organization METHod for Enrichment of Evaluations (PROMETHEE), ELimination Et Choix Traduisant la Realité (ELECTRE III), Technique for Order Preferences by Similarity to Ideal Solution (TOPSIS) and Weighted Sum Algorithm (WSA(). The main result of this study is the creation of a realistic and objective overview of floating offshore wind farm site selection and the contribution to minimize the environmental impacts and to reduce the social conflicts between stakeholders.

In this paper, simulations of a ship travelling on a given oceanic route were performed by a weather routing system to provide a large realistic navigation data set, which could represent a collection of data obtained on board a ship in operation. This data set was employed to train a neural network computing system in order to predict ship speed and fuel consumption. The model was trained using the Levenberg–Marquardt backpropagation scheme to establish the relation between the ship speed and the respective propulsion configuration for the existing sea conditions, i.e., the output torque of the main engine, the revolutions per minute of the propulsion shaft, the significant wave height, and the peak period of the waves, together with the relative angle of wave encounter. Additional results were obtained by also using the model to train the relationship between the same inputs used to determine the speed of the ship and the fuel consumption. A sensitivity analysis was performed to analyze the artificial neural network capability to forecast the ship speed and fuel oil consumption without information on the status of the engine (the revolutions per minute and torque) using as inputs only the information of the sea state. The results obtained with the neural network model show very good accuracy both in the prediction of the speed of the vessel and the fuel consumption.

This study presents a practical optimization procedure that couples the NavCad power prediction tool and a nonlinear optimizer integrated into the Matlab environment. This developed model aims at selecting a propeller at the engine operating point with minimum fuel consumption for different ship speeds in calm water condition. The procedure takes into account both the efficiency of the propeller and the specific fuel consumption of the engine. It is focused on reducing fuel consumption for the expected operational profile of the ship, contributing to energy efficiency in a complementary way as ship routing does. This model assists the ship and propeller designers in selecting the main parameters of the geometry, the operating point of a fixed-pitch propeller from Wageningen B-series and to define the gearbox ratio by minimizing the fuel consumption of a container ship, rather than only maximizing the propeller efficiency. Optimized results of the performance of several marine propellers with different number of blades working at different cruising speeds are also presented for comparison, while verifying the strength, cavitation and noise issues for each simulated case.

The hydrodynamic interaction induced by the complex flow around a ship maneuvering in restricted waters has a significant influence on navigation safety. In particular, when a ship moves in the vicinity of a bank, the hydrodynamic interaction forces caused by the bank effect can significantly affect the ship’s maneuverability. An efficient algorithm integrated in onboard systems or simulators for capturing the bank effect with fair accuracy would benefit navigation safety. In this study, an algorithm based on the potential-flow theory is presented for efficient calculation of ship-bank hydrodynamic interaction forces. Under the low Froude number assumption, the free surface boundary condition is approximated using the double-body model. A layer of sources is dynamically distributed on part of the seabed and bank in the vicinity of the ship to model the boundary conditions. The sinkage and trim are iteratively solved via hydrostatic balance, and the importance of including sinkage and trim is investigated. To validate the numerical method, a series of simulations with various configurations are carried out, and the results are compared with experiment and numerical results obtained with RANSE-based and Rankine source methods. The comparison and analysis show the accuracy of the method proposed in this paper satisfactory except for extreme shallow water cases.

A technique to analyse the economic viability of offshore farms composed of wave energy converters is proposed. Firstly, the inputs, whose value will be considered afterwards in the economic step, was calculated using geographic information software. Secondly, the energy produced by each wave converter was calculated. Then the economic factors were computed. Finally, the restriction that considers the depth of the region (bathymetry) was put together with the economic outputs, whose value depends on the floating Wave Energy Converter (WEC). The method proposed was applied to the Cantabric and Atlantic coasts in the north of Spain, a region with a good offshore wave energy resource. In addition, three representative WECs were studied: Pelamis, AquaBuoy and Wave Dragon; and five options for electric tariffs were analysed. Results show the Wave Energy Converter that has the best results regarding its LCOE (Levelized Cost of Energy), IRR (Internal Rate of Return) and NPV (Net Present Value), and which area is best for the development of a wave farm.

The potential growth found inthe short sea shipping sector motivated the development of a methodology usedas a decision support tool in which both the parameters regarding the demand ofmarkets and the characteristics of the fleet may be tested for its evaluation.It is also possible to determine the fleet deployment, establishing its routesand scales in the ports for a particular scenario. The considered methodologymay be divided in two parts, being the first one related with the generation ofall feasible routes, alongside all the parameters specific to each route foreach vessel class. The second part is the introduction of a linear programmingmodel that maximizes the shipping operation’s total profit, according a givenset of restrictions. The models were structured according to three main criteria:the evaluation of the fleet for each vessel’s class; the optimal route for eachvessel and the frequency in each port. To provide the methodology’s validation,the developed models shall be submitted to a fictitious operational scenario,considering three different situations: the fleet’s normal operation; aparametric variation of required demand for the same fleet composition; anevaluation of several fleet compositions for the same demand level.

The objective of the present work is to perform an evaluation of the performance provided by various technologies for wave energy conversion in the Portuguese continental coastal environment. The wave climate in the target area is first analyzed using the results from three years of simulations with a wave prediction system based on numerical models. Based on the above data, diagrams for the bivariate distributions of the sea states occurrences, defined by the significant wave height and the energy period, are designed for both winters and whole years. On this basis, the output of five different technologies for the conversion of wave energy is assessed in some relevant locations from the Portuguese nearshore. According to the results obtained, the Portuguese continental coastal environment appears to be appropriate for the wave energy extraction. At the same time, the present work shows that the output of the wave energy conversion devices does not depend only on the average wave energy but is also dependent on the distribution of the wave energy among the sea states of different periods. For this reason, a good agreement between the characteristics of the power matrices of the wave energy converters operating in a certain place and the diagrams for the bivariate distributions of the sea states occurrences corresponding to the considered location represents a key issue in selecting the most appropriate technology for wave energy conversion.

The wave energy in a shallow water location is evaluated considering the influence of the local tide and wind on the wave propagation. The target is the coastal area just north of the Portuguese city of Peniche, where a wave energy converter operates on the sea bottom. A wave modelling system based on SWAN has been implemented and focused on this coastal environment in a multilevel computational scheme. The first three SWAN computational belonging to this wave prediction system were defined using the spherical coordinates. In the highest resolution computational domain, Cartesian coordinates have been considered, with a resolution of 25 m in both directions. An in-depth analysis of the main characteristics of the environmental matrix has been performed. This is based on the results of eight-year model system simulations (2005–2012). New simulations have been carried out in the last two computational domains with the most relevant wave and wind patterns, considering also the tide effect. The results show that the tide level, together with the wind intensity and direction, may influence to a significant degree the wave characteristics. This especially concerns the wave power in the location where the wave converter operates.