Coastal Vessels Research Articles

Cavity shape measurement on propeller blade surface by combination line CCD camera measurement method

ABSTRACT A new combination-line-CCD camera method has been developed to accurately measure three-dimensional propeller blade cavitation shapes and volumes, which strongly correlate with pressure fluctuations. The effectiveness of this system was validated through model experiments conducted in NMRI's large cavitation tunnel using a propeller for a 749GT coastal vessel. The accuracy was verified by comparing the estimated pressure fluctuation, derived from the cavity volume, with the pressure sensor measurements. In the estimation, the unsteady cavity is replaced by a moving spherical bubble with a varying radius, and the pressure fluctuation induced by the sphere is calculated. Applying the proposed method to the experimental cavity shape data yielded pressure fluctuation estimates that closely matched the pressure sensor measurements. This result demonstrates the strong correlation between the time variability of the cavity volume and the pressure fluctuation induced by cavitation in the model tests.

Safety on automated passenger ships: Exploration of evacuation scenarios for coastal vessels

Many advancements are being made within the domain of autonomous shipping, motivating discussions of corresponding amendments to international safety regulations within the International Maritime Organization. Near-coastal passenger ferries are a form of sea traffic that has been the target of automation trials due to their short voyages and relatively protected waters of operation. This study investigated emergency evacuation from a range of such ships, covering both the current situation (focused on crew tasks, external rescue actors and interactions) and safety aspects that should be considered when automation brings about new work patterns, such as remote supervision and control. The study employed qualitative methods – interviews, field visits and a stakeholder workshop. Results give insight into ferry evacuation processes and challenges in their current form. In addition, results from the application of different automated evacuation scenarios suggest that more detailed studies are needed within the areas of remote operation situation awareness, remote operator and onboard personnel competencies, passenger safety information and communication, simple and robust evacuation equipment, technical means allowing assistance between autonomous and regular ships, and lastly, both procedures and interfaces for collaboration in a changing rescue network.

A model of the radar situation of the coastal vessel traffic control system

Since the elements of the ship traffic control system at sea (VTS) are geographically distributed, and the observed spaces have well-defined zones, the radar facilities (radars) that make up their technological basis are evaluated by the ability to detect, classify (recognize), and ensure tracking of ships at a certain range in the spatial zone. The solution of these problems is probabilistic in nature, and the indicators are represented by random functions. However, due to the complexity of accounting for random factors in such stochastic control systems, calculations of their efficiency indicators are usually carried out deterministically for the "average" values of random parameters. The development of a mathematical model for evaluating the effectiveness of VTS in its ability to detect marine targets is a scientific task, the solution of which is possible using elements of the theory of random functions and processes.

Joint decision of green technology adoption and sailing pattern for a coastal ship under ECAs

In order to comply with the latest Emission Control Areas (ECAs) regulations, ships must use expensive low-sulphur fuel oil or relatively cheap high-sulphur fuel oil (HFO) with desulphurization equipment. This study investigates the choice of green fuel and green technology for a coastal container ship with endogenous decision of sailing pattern. The sufficient and necessary conditions for a ship to adopt scrubber installation (SI) strategy are derived, which is dependent on factors including the equivalent sailing distance, the fuel price ratio, and scrubber parameters. The case study based on the China's coastal area is conducted. Numerical examples show that the introduction of scrubber technology on coastal vessels will reduce their evasion behavior. However, the increased sulphur reduction efficiency of scrubbers increases the evasion strategies of ships, which will increase the total emissions in coastal areas. The numerical example shows that introduction the scrubber technology to the coastal ships will reduce their evasion behavior. However, the scrubber investment will increase ships' sailing speed, increasing emissions within ECA. Therefore, governments can subsidize high abatement efficiencies of the scrubber to reduce actual ship emissions.

Snapshots in time: quantifying dynamics of coastal vessel traffic in a dolphin hotspot

ABSTRACT Small vessels contribute substantially to coastal soundscapes, presenting myriad potential impacts on marine species and ecosystems, yet are challenging to monitor using standard tracking methods (e.g. AIS). Here, we present an automated camera system developed to quantify coastal vessel traffic in a core habitat for Hector’s dolphins (Cephalorhynchus hectori) within Akaroa Harbour, Aotearoa New Zealand. Analysis of 55,569 images taken during the austral summer of 2019/20 showed that traffic was highest around midday, on weekends, and in January. A mean of 41.9 vessel trips per day transited the area of core habitat. Vessel speeds estimated from photographs were assigned to 5-knot bins with 84% accuracy. Findings suggest vessel traffic in Akaroa Harbour has approximately doubled between 2006–2008 and 2020. Additionally, tours focused specifically on dolphins composed a significantly larger proportion of vessel traffic in 2020 than observed during 2006–2008. We validate the use of an automated camera system as a robust, novel, repeatable, and cost-effective tool for quantifying fluctuations in coastal vessel traffic. Such tools can provide baseline data and help assess impacts, and their use can guide management action.

The Effect of a Web-Based Occupational Noise-Induced Hearing Loss Prevention Program on Hearing Protection Device Behavior Among Thai Navy Officers: A Quasi-Experimental Study

Navy officers working on the coastal guard vessels risk hearing loss due to repeated exposure to high noise levels from ship engines. Therefore, proper use of hearing protection devices is important. In this study, a web-based hearing loss prevention program was developed to promote the behavior of the use of hearing protection devices among Thai navy officers working on coastal guard vessels. In total, 152 navy personnel were recruited based on selection criteria and randomly assigned to the experimental (n = 76) and control groups (n = 76). The participants in the experimental group received the hearing loss prevention program via a website over four weeks. After completing the program, hearing protection device behavior was evaluated by a self-report questionnaire immediately after and at eight weeks follow-up. The results showed significantly increasing scores of the use of hearing protection devices behavior within the experimental group, both immediately and eight weeks after the program completion. However, there were no significant differences in the scores when comparing between groups, even though the scores of the experimental group were better than those in the control group. The restrictions could be explained by some emerging events during the implementation period, including the COVID-19 pandemic followed by a massive oil spill incident at sea. These put an extra workload on the study participants. Most importantly, there was a problem with the network connection that might have affected the continuation of participant attention to the program. Although this study found no effective results of the developed program due to some limitations, nurses can adopt this protective intervention to reduce the risk of occupational noise-induced hearing loss among Navy officers. Therefore, a recommendation for further study is to develop an intervention program that considers both the working context of the coastal vessels and appropriate participation methods that require more challenging efforts.

Development and demonstration of strategies for GHG and methane slip reduction from dual-fuel natural gas coastal vessels

Low Pressure Dual Fuel (LPDF) marine engines fueled with natural gas (NG) provide a cost-effective means for minimizing fuel sulfur content, and NOx and PM emissions for marine vessels. In addition, the use of NG can provide significant GHG reductions, if CH4 slip is mitigated. Alternative fueling strategies such as LPDF, are commonly assessed by life-cycle analyses using exhaust emission rates from generalized engine test cycles (e.g. IMO E2). As CH4 slip from LPDF NG engines is particularly sensitive to engine load, a greenhouse gas emission inventory based on generalized engine cycles may not accurately represent real-world vessel operation and emissions. The objectives of this work are to: (i) quantify the GHG emissions reductions possible using the current best available LPDF technology and, (ii) evaluate the attained real-world emissions reduction as a result of improved vessel operating strategies and state of the art engine technology for coastal LPDF vessels.Steady-state emission factors (g/kW-h) and emission rates (g/h) of CH4, CO, CO2, and NOx were measured during steady-state and dynamic operation for two roll-on-roll-off ferries with LPDF engines from two different manufacturers. During commercial operation, the combination of a revised LPDF engine calibration and best vessel operating strategy reduced GHG emissions by 57% and 24%, relative to stock LPDF and diesel operation on vessel #1, respectively. Compared to diesel operation, the annual GHG savings on vessel #1 as a result of this program equate to approximately 2.4 kT CO2e. The tank-to-wake CH4 emissions measured in the current and previous works were found to have poor agreement with the those based on the corresponding test cycle (E2). The E2 cycle overestimated the current CH4 emissions by 8–30% depending on the implemented operating strategy. Prior to implementation of these strategies, the E2 cycle underestimated the CH4 emissions by 74% (Peng et al., 2020). This underscores the value of in-use emission measurements for accurate evaluation of alternative fueling strategies, as well as the utility of emission-informed vessel operation strategies.

System-Level Consideration and Multiphysics Design of Propulsion Motor for Fully Electrified Battery Powered Car Ferry Propulsion System

The Korean government is facing growing concern over the increasing levels of fine dust. A significant contribution to this problem comes from coastal vessels. To mitigate this, an electric ship propulsion system has been proposed as a solution to reduce air pollution. The application of a fully electric propulsion system in a ship is challenging due to size, capacity limitations, and the cost investment of the battery system. To address the challenges of battery limitation and initial investment costs, the development and supply of removable battery supply systems (RBSSs) for fully electrified battery powered (F-EBP) car ferries are studied. A permanent magnet synchronous motor (PMSM) for the F-EBP car ferry using a roll-on/roll-off-type RBSS is developed in this work. Firstly, the concept of the F-EBP car ferry is discussed, and the specifications of the electric car ferry propulsion system are provided. Secondly, motor design and electromagnetic analysis are performed using finite-element analysis (FEA), where the heat sources including copper loss, core loss, and PM loss are calculated. Mechanical loss is also considered. Finally, a thermal network of the motor is built considering the lumped-parameter model. The results of the thermal analysis indicate that the motor operates within the safe region and can perform well in rated working conditions.

European coastal monitoring programmes may fail to identify impacts on benthic macrofauna caused by bottom trawling

Bottom trawling (hereafter trawling) is the dominant human pressure impacting continental shelves globally. However, due to ongoing data deficiencies for smaller coastal vessels, the effects of trawling on nearshore seabed ecosystems are poorly understood. In Europe, the Water Framework Directive (WFD) provides a framework for the protection and improvement of coastal water bodies. It requires member states to track the status of ‘biological quality elements’ (including benthic macrofauna) using WFD-specific ecological indicators. While many of these metrics are sensitive to coastal pressures such as nutrient enrichment, little is known about their ability to detect trawling impacts. Here, we analysed a comprehensive data set of 5885 nearshore benthic samples – spatiotemporally matched to high-resolution trawling and environmental data – to examine how these pressures affect coastal benthos. In addition, we investigated the ability of 8 widely-used benthic monitoring metrics to detect impacts on benthic biological quality. We found that abundance (N) and species richness (S) were strongly impacted by bottom trawling. A clear response to trawling was also observed for the WFD-specific Benthic Quality Index (BQI). Relationships between N and S, and trawling were particularly consistent across the study area, indicating sensitivity across varying environmental conditions. In contrast, WFD indices such as AZTIs Marine Biotic Index (AMBI), multivariate AMBI (M-AMBI), and the Danish Quality Index (DKI), were unresponsive to trawling. In fact, some of the most heavily trawled areas examined were classified as being of ‘high/good ecological status’ by these indices. A likely explanation for this is that the indices are calculated using species sensitivity scores, based on expected species response to eutrophication and chemical pollution. While the BQI also uses species sensitivity scores, these are based on observed responses to disturbance gradients comprising a range of coastal pressures. Given the prominent use of AMBI and DKI throughout Europe, our results highlight the considerable risk that the metrics used to assess Good Ecological Status (GES) under the WFD may fail to identify trawling impacts. As trawling represents a widespread source of coastal disturbance, fishing impacts on benthic macrofauna may be underestimated, or go undetected, in many coastal monitoring programmes around Europe.

The GATERS Project – An innovative way of retrofitting ships for greener and safer operations

This paper presents the first-year activities of the H2020 Innovation Action project GATERS for greener propulsion of ships using an innovative retrofit energy-saving and steering device, the Gate Rudder System (GRS). One of the project's main aims is to retrofit a target coastal vessel with a GRS for the first time and demonstrate its effectiveness. The target vessel is the existing 6400 DWT general cargo ship (MV Erge), currently fitted with a high-lift conventional rudder system (CRS), which a retrofit GRS will replace in GATERS as one of the project aims. This paper provides a background of GRS technology and the project motivation, including a brief project overview. The details of the retrofit task involving the design of the main GRS components and estimated power-saving are also reported in the paper. The vessel is scheduled to be retrofitted in December 2022 for demonstration and further performance monitoring.

Relación entre frentes de convergencia y localización de la flota pesquera durante la ocurrencia de surgencia costera en Uruguay

The Uruguayan coast presents upwelling events during the summer, its implications on the distribution, transport of nutrients and organisms; and their effects on the entire food web, have not been previously analyzed. This work seeks to understand the relationship between the upwelling events and the location of the Uruguayan coastal industrial fleet (B Category). Finite Size Lyapunov Exponents (FSLE) were computed from surface current velocity fields. The temporal averages of these exponents indicate the mixing intensity and presented higher values over the region of more intense upwelling. On the other hand, the maximum FSLE values identify convergence fronts. The fronts identified by this methodology correspond to the turbidity front and close to Montevideo, and temperature fronts directly associated with the upwelling event. During the event, these fronts migrated from the coast, to the southwest and offshore. The location of the frontal regions detected was compared with the satellite position (VMS) of B Category coastal vessels of the Uruguayan fishing fleet. In general, the vessels were positioned on the frontal zones, suggesting a relationship between retention processes and the location of target species; and evidencing the need to deepen the study of these processes.

The small pelagics value chain in Mauritania – Recent changes and food security impacts

This paper identifies the effect of Mauritian regulation changes on EU industrial vessels’ fishing activities and their implications for food security. The rich resources of Mauritanian waters have historically been utilized by large foreign trawlers, creating small ripple effects and jobs in Mauritania. However, in 2012, Mauritanian authorities introduced new restrictive access conditions; a 20 nautical mile limit and an obligation to land fish caught in this area in Mauritania, so as the national fishing industry to play a more important role. This resulted in significant changes to vessel fishing strategies and distribution channels. For instance, EU vessels that had supplied markets in the Gulf of Guinea, providing a low-cost source of protein to populations, were now unable to exploit the important sardinella resources that migrate along the coast for such purposes. Instead, these resources are now harvested by Turkish coastal vessels, supplying a very recent large fishmeal and oil industry based in Mauritania. Large quantities of small pelagics have thus been redirected from being valuable food products to creating fishmeal aimed at non-human uses. Moreover, this change has put the small pelagics stocks under pressure and most species are currently overexploited. Mauritania, under its current 2021–25 policy, is presently implementing measures to develop a fish processing industry aimed at human consumption, to which European vessels can supply fish. Yet, further improvements are still required in the business environment, such as transparency, regulatory framework and fiscal issues, to enhance regional food security.

Increasing catch efficiency for Nephrops in deep-water shrimp (Pandalus borealis) trawl fisheries

In Skagerrak and the North Sea, coastal vessels harvest deep-water shrimp (Pandalus borealis) in a mixed fishery, in which catches of Nephrops (Nephrops norvegicus) are of economic importance for the fleet. Fishermen targeting shrimp in this area must use a sorting grid with a maximum bar spacing of 19 mm, which means that only the smallest Nephrops can pass through the grid to be retained in the main codend. Although fish collection bags may be mounted to the grid’s fish outlet, most Nephrops escape through the large meshes in these bags. Using data from 70 hauls collected during three different commercial cruises, we investigated whether inserting a 15 cm gap in the lower part of the compulsory sorting grid could help retain a higher fraction of the commercial sizes of Nephrops. We also evaluated whether this lower gap in the grid would change the catch pattern for the most relevant fish bycatch species in the fishery. The results showed that the gap in the grid significantly increased the catches of Nephrops above the minimum legal size and increased the catches of commercial-size shrimp. However, absolute catch rates of Nephrops were still low and, from a management point of view, the modest catch increase does not justify the significant increase in the catch of juveniles of a range of fish species as well as undersized Nephrops.

Climate change mitigation of drop-in biofuels for deep-sea shipping under a prospective life-cycle assessment

The shipping sector is seeking options to reduce its emissions of greenhouse gases (GHGs) and achieve ambitious climate change mitigation goals. Unlike short-sea shipping that can rely on electrification of coastal vessels, drop-in biofuels are among the most promising options for deep-sea shipping decarbonization. However, environmental sustainability analyses of marine biofuels are limited, and usually do not include the influence of future changes in the background energy system nor the climatic effects of near-term climate forcers (NTCFs). In our study, we assess the climate change mitigation potential of various marine biofuels produced from forest residues in Norway (a country with ambitious plans for emission reduction from shipping) using a prospective life-cycle assessment (LCA) where the projected trends in the energy and transport sectors are integrated with improvements in the biofuel value chain for the next decades (2030–2050). Relative to fossil-based alternatives, climate mitigation potentials of biofuels range from 65% to 85% with short-term (GWP20) and to 78%–87% with long-term (GTP100) climate impacts. The inclusion of NTCFs reduces the mitigation benefits of biofuels in the short term, while it slightly increases them in the long term. The explicit modeling of technology and socio-economic changes under future policy scenarios indicates a reduction in the climate impacts of biofuels by up to 54% in 2050 when compared to the current situation. The amount of residues potentially available in Norway is sufficient to meet the present demand for liquid fuels in deep-sea shipping, thus providing yearly climate mitigation of 0.9–1.1 million tons of CO2-eq (equal to 6–7% of today's climate impacts from the entire transport sector in the country). Our analysis shows the large climate change mitigation potential of drop-in biofuels, and it provides new quantitative estimates that can help guiding a sustainability shift in the deep-sea shipping sector.

Multi-level Model for Ships Risk Assessment by Coastal Vessel Traffic Services

The article is devoted to the problem of navigation safety of sea vessels’s movement. An approach is considered that allows generating alarm signals with the allocation of various levels of danger. The criterion for the division of hazard levels is based on the trajectory properties of the movement of ships. A system of rules is proposed, which appeals to model representations of the “ship-to-ship” type and allows to streamline the actions of the dispatcher when controlling the collective movement of ships. The results of modelling and field study of traffic in the water area of the port of Vladivostok, which confirm the constructiveness of the proposed ideas, are presented.

A Life Less than Ordinary: The Schooner Ocean (1821\u20131865)

The East Winner Bank Shipwreck takes its name from the southern sandbank on Hayling Island near Portsmouth, UK. Examination of the wreck indicates a 19th-century carvel-built vessel. The sandbank is an active environment, meaning the wreck is rarely exposed to its full extent. Discussed here is work completed on the site before and during the social-distancing restrictions imposed by COVID-19. Documentary sources and previous detailed surveys suggest a possible identification for the wreck. The site appears to be an example of an everyday 19th-century coastal trading vessel, rarely explored archaeologically in the UK, with potential to contribute to discussions of the maritime technologies and maritime cultural landscape of regular folk. The investigation represents an excellent example of combining historical and archaeological data sets to further the interpretation of both sources, revealing details about the ship and its lasting impact on this stretch of coastline.

Development and Demonstration of Strategies for GHG and Methane Slip Reduction from Dual-Fuel Natural Gas Coastal Vessels

Development and Demonstration of Strategies for GHG and Methane Slip Reduction from Dual-Fuel Natural Gas Coastal Vessels

Identifying Métiers Using Landings Profiles: An Octopus-Driven Multi-Gear Coastal Fleet

The multi-gear coastal vessels in the Algarve (South Portugal) own licenses for various fishing gears. However, it is generally uncertain what gears they use, which is problematic as each individual gear is responsible for unique impacts on the resources and the environment. In this study, landing profiles identified for the multi-gear coastal fleet (2012–2016) were used as support in defining potential métiers using k-mean clustering analysis (CLARA) along with information from past studies on métiers. The results showed that more than 50% of the vessels were engaged in the octopus fishery year-round, using traps, while a small percentage (~13%) were entirely dedicated to clam dredging. In general, gillnets (21%) were used to target monkfish, hake and bastard soles, while trammel nets (6%) were used to target cuttlefish, with some vessels alternating the fishing gears (either seasonally or annually) according to target species. The method for the initial characterization of this fleet’s métiers and its efficiency with limited data is discussed, as well as the utility of this segmentation in support of management advice.

Ship emissions around China under gradually promoted control policies from 2016 to 2019

Abstract. Ship emissions and coastal air pollution around China are expected to be alleviated with the gradual implementation of ship domestic emission control area (DECA) policies. However, a comprehensive post-assessment on the policy's effectiveness is still lacking. This study developed a series of high-spatiotemporal ship emission inventories around China from 2016 to 2019 based on an updated Ship Emission Inventory Model (SEIM v2.0) and analyzed the interannual changes in emissions under the influence of both ship activity increases and gradually promoted policies. In this model, NOx, SO2, PM and HC emissions from ships in China's inland rivers and the 200 Nm (nautical miles) coastal zone were estimated every day with a spatial resolution of 0.05∘×0.05∘ based on a combination of automatic identification system (AIS) data and the Ship Technical Specifications Database (STSD). The route restoration technology and classification of ocean-going vessels (OGVs), coastal vessels (CVs) and river vessels (RVs) has greatly improved our model in the spatial distribution of ship emissions. From 2016 to 2019, SO2 and PM emissions from ships decreased by 29.6 % and 26.4 %, respectively, while ship NOx emissions increased by 13.0 %. Although the DECA 1.0 policy was implemented in 2017, it was not until 2019 when DECA 2.0 came into effect that a significant emission reduction was achieved, e.g., a year-on-year decrease of 33.3 %, regarding SO2. Considering the potential emissions brought by the continuous growth of maritime trade, however, an even larger SO2 emission reduction effect of 39.8 % was achieved in these 4 years compared with the scenario without switching to cleaner fuel. Containers and bulk carriers are still the dominant contributors to ship emissions, and newly built, large ships and ships using clean fuel oil account for an increasingly large proportion of emission structures. A total of 4 years of consecutive daily ship emissions were presented for major ports, which reflects the influence of the step-by-step DECA policy on emissions in a timely manner and may provide useful references for port observation experiments and local policy making. In addition, the spatial distribution shows that a number of ships detoured outside the scope of DECA 2.0 in 2019, perhaps to save costs on more expensive low-sulfur oil, which would increase emissions in farther maritime areas. The multiyear ship emission inventory provides high-quality datasets for air-quality and dispersion modeling, as well as verifications for in situ observation experiments, which may also guide further ship emission control directions in China.

Steering model identification and control design of autonomous ship: a complete experimental study

ABSTRACT Steering ship models are important for the study of autonomous ship manoeuverability and design of ship motion control system. It is always a difficult task to find the mathematical model by first principle as it needs prior knowledge of hydrodynamic derivatives. The input–output-based system identification theory can be used to establish system mathematical models. A solution is offered by developing a Wi-Fi-based self-propelled, autonomous system for a ship model with Internet of Things (IoT) capabilities to perform manoeuvering and seakeeping tests in indoor environment without any complex mechanical structure, viz. following bridge. The developed autonomous on-board system equipped with main computer, suitable electronics, sensors, data acquisition system and Wi-Fi-based communication system. The developed system offers a cost effective, modular and portable solution to perform hydrodynamic studies of different hull form without incorporating major changes in the system. The use of IoT makes the data accessible to a naval architecture in real-time to analyse the motion response of the ship in different wave conditions and enables to implement the digital twin to simulate the real field scenario. Input–output-based model identification experiments such as turning circle and zig-zag tests are conducted to estimate the first-order steering model parameters and is further extended to design and implementation of a classical proportional–derivative-based steering control. The design is described in this paper with details of implementation on a demonstration oceanographic coastal research vessel. It illustrates the excellent communication between shore station computer and the on-board system on a wire-free model with robust control and exhibiting all the motion behaviour and dynamic effects. Experiments performed in wave basin in different wave conditions validate the efficacy of the proffered method.