Design of a Hybrid Propulsion Architecture for Midsize Boats

Abstract This paper presents preliminary evaluations on the design of hybrid propulsion architectures related to midsize boats. The analysis is carried out for the case study of a retrofit operation proposed for an oceanographic ship, which is used by the researchers of the National Research Council of Italy for experimental campaigns in the Mediterranean Sea. Starting from the information obtained on the existing architecture by means of various on-board inspections, an experimental set-up is proposed for the monitoring and acquisition of the main electrical and mechanical parameters of the ship, during her navigation campaigns. Different possible hybrid configurations are also proposed, identifying the main advantages and drawbacks of each configuration for the considered application. The proposed set-up allows obtaining experimental information, about the behaviour of the ship in a large variety of operative conditions, which will be useful to support the choice of a proper hybrid propulsion architecture and the optimal design of components

Otterboard hydrodynamic performance testing in flume tank and wind tunnel facilities

© 2017 Elsevier LtdTwo pelagic otterboards, previously tested in a wind tunnel, have been tested in a flume tank prior to their analysis in real working conditions in sea trials. This intermediate step aims at providing guidance for sea trial planning and a basis for otter board performance analysis from real campaign data. The doors were rigged in working-like conditions in the flume tank, with onboard-mounted attitude sensors to provide at the same time a noisy environment as expected in sea trials and accurate measurement of all quantities relevant to precise determination of hydrodynamic angles and forces. The trends found in flume tank experiments closely match wind tunnel results, although systematic offset has been observed that can be ascribed to deviations between nominal and real water velocity, due to inhomogeneous velocity distribution in the cross-section.Peer ReviewedPostprint (author's final draft

Fisheries Bycatch of Chondrichthyes

This chapter reviews the current state of knowledge about global chondrichthyes bycatch, including how the combination of biological characteristics of these species and the impact of different fishing methods reflect their vulnerability to bycatch. Specifically, it summarizes the present status of elasmobranchs and chimaeras bycatch worldwide. Following this, it illustrates the main ecological consequences behind such incidental captures. Hence, it provides a description of how chondrichthyes bycatch occurs across broad fishing gear categories. Moreover, it outlines potential mitigation options available to reduce bycatch. As such, the main technical measures tested and applied in different fishing practices are listed. In addition, an overview about which are the current management measures implemented at international level to ensure long-term conservation of cartilaginous fish is reported. Then, two case studies summarize how chondrichthyes bycatch occurred in some of the most exploited fishing areas. Finally, the chapter ends with relevant considerations about potential for new research needed to monitor and reduce chondrichthyes bycatch

Effect of a lateral square-mesh panel on the catch pattern and catch efficiency in a Mediterranean bottom trawl fishery

The current legal codends used in Mediterranean bottom trawl fisheries are at high risk of retaining undersized individuals of several commercial fish species. This entails that codends alone are unable to provide the desired exploitation pattern. A simple technological measure that potentially can provide higher release efficiency of undersized fish are Square-Mesh Panels (SMPs). SMPs are often applied in the upper section of the trawl belly, just ahead the codend. However, recent studies in the Mediterranean have demonstrated that SMPs mounted in this position provided limited release efficiency, because very few fish came into contact with their meshes. In attempt to improve SMPs efficiency in the Mediterranean bottom trawl fisheries, we applied them on the lateral sides of the last tapered section of the trawl belly, just ahead of the codend, and fitted two guiding panels in the trawl belly to enhance fish-SMP contact. We compared the catch performance of a standard commercial trawl with a 52 mm diamond-mesh codend and of a similar trawl fitted with lateral SMPs (70 mm mesh size) in the belly using a twin trawl. The study focused on red mullet (Mullus barbatus), a commercially important species, but data for gurnard (Chelidonichthys lucerna and Chelidonichthys cuculus)  were also obtained and analysed. In contrast to previous research on SMPs mounted in the top panel of the trawl, in this study SMPs induced a significant effect on catch performance for red mullet, demonstrating that their lateral position involved greater fish-SMP contact. However, since the test trawl lost a significant amount of legal-sized red mullet compared with the standard trawl, the effect was not wholly positive, possibly due to an excessively large mesh size. Therefore, future studies should be encouraged to test lateral SMPs with smaller mesh sizes

Fishing the waves: comparing GAMs and random forest to evaluate the effect of changing marine conditions on the energy performance of vessels

The optimization of consumption and the reduction of gas emissions in fisheries rely on a thorough examination of all factors affecting the energy balance of fishing vessels. Engines, propellers, or the hydrodynamic characteristics of vessels and gears are unquestionably the primary factors affecting this balance, and an improvement in energy efficiency based on these factors is typically attained through technical modifications to existing technologies. Behavioral modifications, such as a reduction in operational speeds or the selection of closer fishing grounds, are another option. There may still be room for improvement in behavioral responses, for instance by adapting fishing strategies in response to changing weather and sea conditions. As far as the authors are aware, the influence of varying sea state and wind conditions on the energy expenditure of fishing vessels has not yet been investigated and is the focus of this research. In this study, wind and wave actions were associated with the observed activity of three fishing vessels operating in the northern Adriatic Sea: an OTB, a PTM, and a TBB trawler. The analysis made use of a comparison between two different approaches, generalized additive models (GAMs) and random forest, in order to quantify the significance of each variable on the response and generate consumption forecasts. In our analysis, the observed influence of predictors was significant albeit occasionally ambiguous. Wave height had the most obvious impact on energy expenditure, with the towing and gear handling phases being the most affected by wave action. Conversely, navigation seemed to be mostly unaffected by significant wave heights up to 1.5 meters, with unclear effects on consumption estimated above this threshold. The relationship between winds and fuel consumption was found to be nonlinear and ambiguous; hence, its significance should be investigated further

Experimental assessment of the fouling control coating effect on the fuel consumption rate

Fishing is an energy-intensive economic activity. Research in several fields is conducted to improve the energy and environmental profile of fishing vessels. As regards the technical measures, the assessment of benefits is often hampered by boundary conditions that are difficult to quantify and side effects that are difficult to unravel. This study examined the impact of a fluoropolymer-based fouling release paint on the fuel consumption rate of a Mediterranean bottom trawler. The analysis of a series of sea trial campaigns allowed for a quantitative and qualitative comparison of fuel consumption rate during the regular fishing activities. Comparing the fuel consumption rate before and after the application of the fluoropolymer-based foul-release coating, a reduction in fuel consumption rate was observed and quantified. Other advantages are discussed in this paper regarding the reduction of GHG emission, and the more environmental-friendly approach using biocide-free and non-banned products.JRC.D.2-Water and Marine Resource

Experimental assessment of the fouling control coating effect on the fuel consumption rate

Fishing is an energy-intensive economic activity. Research in several fields is conducted to improve the energy and environmental profile of fishing vessels. As regards the technical measures, the assessment of benefits is often hampered by boundary conditions that are difficult to quantify and side effects that are difficult to unravel. This study examined the impact of a fluoropolymer-based fouling release paint on the fuel consumption rate of a Mediterranean bottom trawler. The analysis of a series of sea trial campaigns allowed for a quantitative and qualitative comparison of fuel consumption rate during the regular fishing activities. Comparing the fuel consumption rate before and after the application of the fluoropolymer-based foul-release coating, a reduction in fuel consumption rate was observed and quantified. Other advantages are discussed in this paper regarding the reduction of GHG emission, and the more environmental-friendly approach using biocide-free and non-banned products

Overall efficiency assessment of a trawler propulsion system based on hydrodynamic performance computations

The energy efficiency evaluation of trawlers becomes more and more relevant as the trend of the government laws follows the path of restrictions to new constructions to encourage improvement to existing vessels, often equipped with outdated technologies. The two conditions a trawler need to meet during its operations, namely the sailing and the trawling phases, require in principle very different performances. Despite the higher speed reached when cruising from ports to fishing grounds, this type of ships experiences increased resistance as well as heavy loaded propellers during the trawling operations at low speed. In the light of the specific tasks of such a kind of vessel, a preliminary assessment of the energy efficiency of the ship-system is of crucial interest to optimize both the operating costs and the impact on the sea environment. In this context, hydrodynamic performances and the propulsion system have direct consequences on the fuel consumption, hence on the operational costs of the vessel. In the proposed model, the engine fuel consumption is evaluated by suitable statistic regression to account for the prime mover performance into the propulsion chain. Ship resistance in calm water and added resistance due to rough sea conditions are computed by a Boundary Element Method. Both are then integrated into the global efficiency assessment method. An application of energy efficiency assessment and optimization of a hard-chine 18 meters trawler is presented. The final results are shown as part of a wider decision support system to optimize the overall performance of the vessel operation in different environmental conditions

Shrimp trap selectivity in a Mediterranean small-scale-fishery

Small-scale shrimp trap fisheries, which have received very little attention in areas with limited potential for economic diversification, could offer a sustainable and socially beneficial option for profitable businesses in these regions. This study explores the effect of mesh size on selectivity of the commercially important narwal shrimp, Plesionika narval, in the Mediterranean Sea. Three different mesh sizes (8 × 8, 12 × 12 and 12 × 25 mm) were tested in fishing trials, with a theoretical Minimum Landing Size (MLS) using a defined maturity size of 12 mm to support interpretation of the results. Using the retention rates and the estimations on population fractions above and below MLS, we show that the use of the smallest- and largest-sized meshes would not support sustainable or efficient fishery. The results demonstrate a significant decrease in capture probability of undersized narwal shrimps with increased mesh size. The medium-sized mesh traps prove to be the best compromise for the fishery with high catch efficiency of commercial size shrimp and a low capture probability of undersized individuals. The results outlined in this article could be used to develop management plans for small-scale trap fisheries as a basis for developing viable enterprises in remote coastal communities.acceptedVersio

Trawling in the Mediterranean: An exploration of empirical relations connecting fishing gears, otterboards and propulsive characteristics of fishing vessels

Fishing pressure is often expressed in terms of a vessels physical attributes, like tonnage and engine power, while a common definition of fishing capacity identifies vessel size as a convenient proxy for the size of the gear used. Nevertheless, these definitions remain arguable, and the refinement of these fishing descriptors is increasingly being considered. A stronger understanding of the relationship between the standard measures of effort and capacity and fishing mortality remains a primary objective, followed by the need to overcome a traditional approach that simply describes effort, capacity and mortality as linearly related, conferring a greater fishing power to larger vessels. In this perspective, the analysis of trawlers’ technical features in relation to the size and power of the vessel might constitute an essential step. This study specifically investigated a collection of trawling gears’ technical specifications collected by CNR-IRBIM, Ancona. The dataset used includes records from several Mediterranean fisheries, and involves three trawling techniques, including single trawling, twin trawling and pair trawling, and diverse trawling gear categories, comprising demersal/bottom 2-panel trawls (OTB2), demersal/bottom 4-panel trawls (OTB4), pelagic 4-panel trawls (PTM4), semi-pelagic 2-panel trawls (OTM2), semi-pelagic 4-panel trawls (OTM4), and a Mediterranean bottom beam trawl (TBB). We analyzed and described the relationships between vessels’ technical features (LOA, towing force, and engine power), some among the main trawl-metrics (headline length, footrope length, trawl length, square width; fishing circle) and the otterboard’s technical features (height, width, and projected area) in an attempt to enhance fishing capacity definition through the inclusion of the fishing gear deployed. Self-organizing maps (SOM) were used to explore the empirical relationships among different parts of the fishing trawl gears, as well as between some of these parts, the otterboard size and the engine power of the vessel.JRC.D.2-Water and Marine Resource