Small Boat Research Articles

The hovering pontoon trap: The tougher, younger sibling in the pontoon trap family

Trap nets are a large, stationary, and fixed type of passive fishing gear that has traditionally been used for catching fish in shallow coastal environments. Despite their large size, catches are often retrieved using small boats, making them less energy demanding compared to active gear types. This, along with the stationary nature of the trap, allows for fishing with relatively low environmental impact due to minimal disturbance of the benthic community. The combination of minimal benthic impact, live catch, low fuel, and selectivity offers great potential for the development of sustainable coastal fisheries.Here, we describe the development of the hovering pontoon trap, a fishing gear with a robust design to resist strong waves and currents, and usable in both shallow and deep waters to catch both pelagic and benthic species. We present results from early case studies targeting benthic Baltic Sea species, including perch (Percha fluventaliis), Atlantic cod (Gadus morhua) and vendace (Coregonus albula), showing similar or improved catches in relation to earlier studies. Further, we show that the hovering pontoon trap was able to withstand harsher conditions than previous bottom-set models, making it a possible solution for the targeting of benthic fish communities in coastal environments.

Reaction of two sciaenid species to passing boats: Insights from passive acoustic localisation

Meagre (Argyrosomus regius) and weakfish (Cynoscion regalis) are two soniferous sciaenid species that use the Tagus estuary (Portugal) to breed. In this highly urbanized environment, fishes must deal with multiple anthropogenic stressors that include high noise levels caused by the intense boat traffic. We investigated how these sciaenids react to ferry boat and small boat passages, by assessing both changes in breeding calling activity with passive acoustic monitoring and escape responses with passive acoustic localisation. We found that meagre reduced calling activity after boat passages, but no such effect was observed in weakfish. Instead, weakfish moved in response to boat passages suggesting an escape response. Meagre also changed positions and dispersion patterns, but movements were more modest. This study uses a cost-effective and non-invasive passive acoustic localisation method to elucidate the behavioural response of soniferous fish to anthropogenic noise for the first time, contributing to our understanding of the way fish react to this stressor. Such knowledge is especially important in contexts where fish are exposed to highly prevalent human-generated noise during the breeding season, such as in busy estuaries and coastal areas.

Small Boats, Border Incredulity, and the Hostile Environment in Britain, 1967–1978

Small Boats, Border Incredulity, and the Hostile Environment in Britain, 1967–1978

Characterization of maritime traffic noise in two areas of the Mediterranean

One of the objectives of the European JPI Oceans DeuteroNoise project is to investigate the soundscapes within different sea basins. Measurement campaigns, including the recording of raw noise data (wave files), have been carried out in the Venice Lagoon, in the North Adriatic and on Barcelona shore. In this work we will present the first results. The data acquired were processed to obtain the characteristic spectrum and noise levels; subsequently the velocity of the particles will be acquired and analysed. The analysis of the recorded data involves the design of a taxonomy of anthropogenic noise sources, e.g. large ships, small boats or any other existing noise source. The recorded data were labelled with these sources, describing their main audio characteristics (spectral distribution, temporal evolution, etc.) for their characterization and future blind identification. Throughout the measurement period, ship and route data were acquired using AIS (Automatic Identification System) and Vessel Monitoring System (VMS) in the measurement sites. The preliminary analysis and labelling, together with ship and route data, will allow the reproduction of acoustic environments of anthropogenic origin in laboratories and the creation of acoustic maps of the basins investigated using commercial software.

Speed dependence, sources, and directivity of small vessel underwater noise.

Small vessels (<10 m) radiate underwater noise in sensitive coastal environments, but there is insufficient knowledge of their noise radiation. Through detailed measurements of seven small boats and a jet ski in a shallow water environment on the Swedish west coast, this study presents results on the speed dependence of small vessel underwater noise, its sources, and its directivity. For vessels with planing hulls, broadband source levels increase with speed until planing is attained. When planing, source level dependence on speed is weak. A detailed noise source analysis of one vessel showed that at low speed, tonals from the engine dominate the noise radiation, whereas at higher speeds, propeller tonals and broadband noise dominate. Noise radiation into different horizontal angles shows little angle dependence, and noise levels relative to the closest point of approach show a similar pattern across all investigated vessels. Received noise levels at approximately 100 m range are not high enough to cause hearing impairment in marine animals, but fast-moving small vessels may cause behavioural reactions or stress responses across several marine animal groups.

Todas las aguas el agua: The Water Within “La casa inundada” by Felisberto Hernández

“La casa inundada” (1960) presents a peculiar, meditative, and uncanny short story by the Uruguayan writer, Felisberto Hernández. The story is narrated via the memories (and the male fantasies) of a writer who once took on the odd job of rowing a large woman around the inside of her flooded house day after day in a small boat. Throughout most of the story, the woman, Margarita, remains a mystery to the narrator and to the reader, as do the reasons for her taciturn disposition and for having purposefully flooded her own house. In this article, rather than rescue what is unknown so that the mysterious woman’s apparent ‘“dirty little secret’” can be recovered from the swell, I explore the ontological, epistemological, and affective attributes of water itself. In so doing, I build on Felisberto’s expanding bibliography, calling particular attention to his understudied motifs of “pereza” and “deslizarse.” Unlike most critics of Felisberto, I utilize concepts that both come from and critique psychoanalysis; additionally, the underappreciated theories of Gaston Bachelard regarding water as a “true mother substance” serve as a vital source of theoretical interpretation. In the course of Felisberto’s story, the narrator comes to believe that, for the motherly—and tantalizing—character of Margarita, “lo que más quería [ella], era comprender el agua.” Ultimately, as I demonstrate, “La casa inundada,” similarly helps readers to better think, understand, and sense water and its myriad ways.

Computations of energetic nearshore waves: Are weakly dispersive phase-resolving models telling the same story?

Three phase-resolving weakly dispersive wave models are used for 2DH (2D depth-integrated) computations of large-scale wave-by-wave processes induced by highly energetic sea/swell (SS) forcing near Haleʻiwa on the North Shore of Oʻahu, Hawaiʻi. The computed model results are compared to observations obtained over a nearshore cross-reef transect and from the basin of a small boat harbor. The level of agreement between the model results and observations in complex coastal environments under highly energetic wave forcing, along with the qualitative consistency among the three models, makes these models good candidates for operational applications in nearshore environments exposed to energetic wave forcing conditions.Spectral analyses inside the harbor and over the reef indicate that all three models generally account for infragravity (IG) spatial modal structures that are consistent with observations and the theory of edge and leaky waves. Over the reef, auto- and cross-spectral analyses reveal that the dominant waveforms are qualitatively reproduced by all three models, as indicated through: (i) the growth of IG wave amplitudes from deeper water to the shallow reef sites; (ii) the agreement of power spectral density peaks at the nearshore locations; and (iii) the remarkable similarity of spatial coherence functions among the models and between the models and observations. The computations of swell entering the small boat harbor at Haleʻiwa demonstrate that the models can successfully reproduce the variability in the narrow IG frequency bands that are spatially dependent and often subject to resonant amplifications.

High-Resolution Sea Surface Target Detection Using Bi-Frequency High-Frequency Surface Wave Radar

The monitoring of the sea surface, whether it is the state of the sea or the position of targets (ships), is an up-to-date research topic. In order to determine localization parameters of ships, we propose a high-resolution algorithm for primary signal processing in high-frequency surface wave radar (HFSWR) which operates at two frequencies. The proposed algorithm is based on a high-resolution estimate of the range–Doppler (RD-HR) map formed at every antenna in the receive antenna array, which is an essential task, because the performance of the entire radar system depends on its estimation. We also propose a new focusing method allowing us to have only one RD-HR map in the detection process, which collects the information from both these carrier frequencies. The goal of the bi-frequency mode of operation is to improve the detectability of targets, because their signals are affected by different Bragg-line interference patterns at different frequencies, as seen on the RD-HR maps during the primary signal processing. Also, the effect of the sea (sea clutter) manifests itself in different ways at different frequencies. Some targets are masked (undetectable) at one frequency, but they become visible at another frequency. By exploiting this, we increase the probability of detection. The bi-frequency architecture (system model) for the localization of sea targets and the novel signal model are presented in this paper. The advantage of bi-frequency mode served as a motivation for testing the detectability of small boats, which is otherwise a very challenging task, primarily because such targets have a small radar reflective surface, they move quickly, and often change their direction. Based on experimentally obtained results, it can be observed that the probability of detection of small boats can also be significantly improved by using a bi-frequency architecture.

Biodiversity of coral reefs and associated seagrass beds in Quy Nhon Bay, Binh Dinh Province

The distribution of critical marine habitats in Quy Nhon Bay, Binh Dinh Province, was assessed with the combination of resolution of Google Earth images and local knowledge through local consultations and ground truthing using small boats to check the sites supporting coral reefs and seagrass beds with local involvement. Detailed surveys on species diversity and conditions of marine habitats were conducted at 24 sites of coral reefs and four sites of seagrass beds at three sites (Nhon Ly, Nhon Hai, Ghenh Rang, and Nhon Chau) in 2016–2017. More than 152 ha of coral reefs, 5 ha of seagrass beds, and 720 species belonging to 7 key groups (290 species of fishes; reef-building corals: 194, molluscs: 123, seaweeds: 47, echinoderms: 40, crustaceans: 20 and seagrasses: 6 species) associated with the above habitats were recorded in the Bay. Among them, 92 species were facing different threats, in which 3 species were endangered (EN), including branching corals (Alveopora minuta), flat pen shells (Atrina vexillum), and top shells (Tectus pyramis); 38 species at vulnerable (VU); and 51 species at near threatened (NT) following the IUCN Red List and Vietnam Red Book. In general, the coral reefs and seagrass beds at Bai Dua and Seo Island (Nhon Ly); Kho Nho Island, Bo Dap (Nhon Hai); S. Ngang Island, Bai Nam and Bai Nom of Dat Island (Ghenh Rang); Da Ban, Bai Lang, Bai Lang Ba and Ong Gia Island (Nhon Chau) supported higher diversity and better conditions than other sites. Establishing restricted zones at these sites is an urgent need, but it also holds the premise of sustainable utilization and conservation of resources in the future.

A float-based Ocean color vicarious calibration program

Ocean color satellites require a procedure known as System Vicarious Calibration (SVC) after launch as the pre-launch and on-orbit calibration accuracy is insufficient. The current approach for determination of post-launch SVC uses a single fixed measurement location and may be susceptible to unexpected biases in satellite processing algorithms. Here we describe a novel SVC program which is based on a high resolution and high accuracy radiometric system integrated with an autonomous profiling float (providing a buoyancy engine, physical observations, and communication). This float + radiometer (HyperNav) system can be shipped via air, land, ocean and is deployable from small boats. This SVC program relies on multiple deployment sites with associated facilities to collect a significant amount of SVC quality data in a relatively short time. It has centralized logistics and command-and-control centers ensuring easy access to information regarding the status of each asset and to ensure floats stay within a certain ocean area. The development of the program has been associated with the launch of NASA’s PACE satellite and has been executed by academic institutions in collaboration with an industrial partner. Other approaches for a future float-based operational SVC program are discussed.

A Study on the Percentage of Pacing Strategies in Elite Asian Rowers: Analysis of Crew, Boat Type, and Gender

Background: For optimal performance, rowers should maintain a consistent rowing cadence over the entire distances. However, the rowing cadence of each category can be influenced by several factors. Understanding the rowing strategy related to these factors may help improve rowing performance. Objective: This analytical research aimed to examine the pacing strategies used by elite Asian rowers in different categories: crew, boat type, and gender during competitions at the 2023 Asian Games. Methods: The official Final A competition results of 14 events, comprising 42 male and 37 female rowers, totaling 79 datasets, were used for statistical analysis. Pacing techniques for each category were analyzed in the 500 m intervals and expressed as a percentage. Pearson correlation coefficient was used to assess rowing interval correlation. Results: The 2- and 2X showed the most percentage change (9.56%), while the 8+ showed the lowest (6.83%). After 8.33% and 8.37% adjustments, sweeps and sculls were essentially identical. Male rowers changed 7.08%, while female rowers changed 9.49%. The 500 m and 1000 m interval had a moderate positive correlation (r = 0.462), while the 2000 m distance had a significant negative correlation (r = -0.750) and the 1000 m had a strong negative correlation (r = -0.818) (p0.05). Conclusion: Rower’s size and gender are the major factors influencing pacing percentage. Smaller boats are more affected than larger ones. Males are less different per interval than females. Crew, boat type, and gender may impact rowing performance during certain intervals. Coaches and athletes need specialized pacing strategies for competition success.

Seeking asylum during a pandemic: A postcolonial media discourse analysis

The beginning of the COVID-19 pandemic in 2020 saw an increase in people seeking asylum in the UK via small boats across the English Channel. The small boat arrivals reported in the news were analyzed using critical discourse analysis to investigate how different outlets framed people seeking sanctuary both visually and linguistically, as well as how postcolonial theory assists an understanding of such discourses. This research conceptualizes common findings in the literature of forced migrants as dehumanized and “othered,” arguing that humanitarian securitization is not an oxymoron but an extension of colonial logic in post-Brexit Britain. The article ends with recommendations for critical reporting of forced migration and for representing people seeking sanctuary in more humanizing ways.

Decreased Smoke Detector Performance Functionon MV. Sarah S

Ships are vessels used for transporting passengers and goods across bodies of water, such as rivers and seas, using canoes or smaller boats. Fires on ships can occur due to various reasons, including interference with electrical and electronic equipment, as well as flammable liquids like gasoline, grease, and gas leaks. This study adopts a descriptive qualitative approach, utilizing data collection methods such as direct field observation, in-depth interviews with involved parties, and documentation/library research. The research findings highlight two main points: 1) The factors leading to decreased functionality of fire alarm sensors are the lack of maintenance and repair of the system; and 2) A decreased fire alarm system may fail to detect fire or smoke in specific areas, potentially leading to accidents or severe damage to the ship.

One-step preparation of highly efficient adsorbents: Adsorption study of DMP on porous carbon macrobody based on sodium alginate

Porous carbon is a carbon material with a high surface area and abundant pore structure, holding extensive potential applications in the adsorption field. However, current porous carbon materials are complicated to prepare, and most are in powder form, making them difficult to separate from water after adsorption and prone to secondary pollution. This study uses sodium alginate (SA) as a precursor and K2CO3 one-step method to prepare sodium alginate-based macromaterials that can skillfully solve the above problems and explore its adsorption kinetics and thermodynamic characteristics for dimethyl phthalate (DMP). This study's meticulous control of experimental details enabled the fabrication of macroscopic materials. The appropriate temperature and activator blending ratio are critical to material agglomeration. (At 800 °C in a small ceramic boat, macroscopic material C800–2 was prepared with an activator ratio of K2CO3: sodium alginate at 2:1 and under low acid concentration acid washing (0.2 mol/L HCl)). Excessive pyrolysis temperature can lead to severe chemical bond loss, potentially preventing material agglomeration. Excessive doping of the activator may result in carbon framework collapse. While maintaining the macroscopic structure, C800–2 enhanced a 3.8-fold increase in total pore volume and a 4.6-fold increase in surface area. Moreover, at 313 K, its saturated adsorption of DMP reached an impressive 614.98 mg/g. C800–2 material exhibits excellent interference resistance and regeneration capability. The study achieves one-step fabrication of macroscopic materials while retaining superior adsorption performance, providing fundamental data for material engineering applications.

Applying Special High-pressure Water Cleaning Method to Bottom of Small Boat

Applying Special High-pressure Water Cleaning Method to Bottom of Small Boat

Artificial Neural Network for Glider Detection in a Marine Environment by Improving a CNN Vision Encoder

Despite major economic and technological advances, much of the ocean remains unexplored, which has led to the use of remotely operated vehicles (ROVs) and gliders for surveying. ROVs and underwater gliders are essential for ocean data collection. Gliders, which control their own buoyancy, are particularly effective unmanned platforms for long-term observations. The traditional method of recovering the glider on a small boat is a risky operation and depends on the skill of the workers. Therefore, a safer, more efficient, and automated system is needed to recover them. In this study, we propose a lightweight artificial neural network for underwater glider detection that is efficient for learning and inference. In order to have a smaller parameter size and faster inference, a convolutional neural network (CNN) vision encoder in an artificial neural network splits an image of a glider into a number of elongated patches that overlap to better preserve the spatial information of the pixels in the horizontal and vertical directions. Global max-pooling, which computes the maximum over all the spatial locations of an input feature, was used to activate the most salient feature vectors at the end of the encoder. As a result of the inference of the glider detection models on the test dataset, the average precision (AP), which indicates the probability that an object is located within the predicted bounding box, shows that the proposed model achieves AP = 99.7%, while the EfficientDet-D2 model for comparison of detection performance achieves AP = 69.2% at an intersection over union (IOU) threshold of 0.5. Similarly, the proposed model achieves an AP of 78.9% and the EfficientDet-D2 model achieves an AP of 50.5% for an IOU threshold of 0.75. These results show that accurate prediction is possible within a wide range of recall for glider position inference in a real ocean environment.

Enhancing the Stability of Small Rescue Boats: A Study on the Necessity and Impact of Hydraulic Interconnected Suspensions

Aiming to solve the problem that existing small rescue boats cannot realize the effective and stable rescue of human lives under high sea turbulence conditions, this paper proposes a parallel decoupled hydraulic interconnected suspension system for actual sea state. The system dynamics model is established, and its damping characteristics are analyzed by joint simulation. The results show that compared with the truss-type rescue ship, the suspension system can improve the transverse rocking resistance by 81.5% and the longitudinal rocking resistance by 25.0%, and the system has excellent transverse rocking resistance.

Small Boats, Big Contracts: Extracting Value from the UK's Post‐Brexit Asylum ‘Crisis’

AbstractThis article discusses post‐Brexit asylum policy in the UK. On the surface, Brexit had little impact on asylum, but Brexit, combined with the new phenomenon of small boat Channel crossings, created the conditions for a new and extreme UK policy agenda. It explains how politicians have sought to deliver border sovereignty performatively after Brexit by introducing extreme measures, ostensibly—though not practically—to stop small boat Channel crossings, and how private actors have sought to profit from people seeking asylum within this policy regime. These interrelated political and financial interests are pursued irrespective of the fact that none of the policies being advanced will ‘stop the boats’.

Clutter evalution of unmanned surface vehicles for maritime traffic monitoring

A traditional maritime radar system is utilized for ship detection and tracking through onshore transmitters and receivers. However, it faces challenges when it comes to detecting small boats. In contrast, unmanned surface vehicles (USVs) have been designed to monitor maritime traffic. They excel in detecting vessels of various sizes and enhance the capabilities and resolution of maritime radar systems. Nevertheless, just like conventional radar systems, USVs encounter difficulties due to environmental interference and clutter, affecting the accuracy of target signal detection. This research proposes a comprehensive numerical assessment to tackle the clutter issue associated with USVs. This involves gathering clutter signal data, performing numerical analysis, and employing distribution fitting techniques that leverage mathematical distributions to unravel data complexity. The root mean square error (RMSE) is applied in this analysis to validate the efficacy of the distribution model. The results of this study aim to formulate a clutter model that can enhance radar performance in detecting small vessels within cluttered environments.

PENGAPLIKASIAN YUKOM VMA SEBAGAI BANTUAN PENANGKAPAN KAPAL GILLNET DI MADASARI, KABUPATEN PANGANDARAN

One of the fishing gears operated in Pangandaran waters is Gillnet. Traditional method to find ocean fish such as star interpretation, water ripples sound caused by fish shoals, and other indicators, is mostly applied by fishers in Pangandaran. To support their fishing operation a smart fishing tool is needed such as a vessel multi aid (VMA), Created by UCT Inc. as a specific maritime telecommunication, a brand name of Yukom VMA has been cooperated to Fishing Centre of the Indonesian Ministry of Marine Affairs and Fisheries. Yukom VMA basically is a assisting tool to find potential fishing ground. The purpose of this study is to examine the effectiveness of Yukom VMA to increase fisher’ catches and their potential utilization. This study was held on August 1, 2021 to September 1, 2021. The method used is descriptive method and direct interviews. The respondents were Gillnet fishers who drop their catch at the landing site (TPI) of Madasari. The features of Yukom VMA are consisted of e-logbook, SOS for emergency, Yukom chat, navigation supports, information of fishing ground sites and weather. This study resulted that Yukom VMA application is effective to increase fisher’s catches, helps fishers to carry out fishing operation, except for fishing ground information, the sites were too far to be reached out using small boat (2-3 GT). The average catch of Madasari fishermen is 102.6 kg with an average number of trips per month 16.7 trip and an average CPUE value of 10.3 kg/trip.