Types Of Vessels Research Articles

A small fishing vessel recognition method using transfer learning based on laser sensors

The management of small vessels has always been key to maritime administration. This paper presents a novel method for recognizing small fishing vessels based on laser sensors. Using four types of small fishing vessels as targets, a recognition method for small fishing vessels based on Markov transition field (MTF) time-series images and VGG-16 transfer learning is proposed. In contrast to conventional methods, this study uses polynomial fitting to obtain the contours of a fishing vessel and transforms one-dimensional vessel contours into two-dimensional time-series images using the MTF coding method. The VGG-16 model is used for the recognition process, and migration learning is applied to improve the results. The UCR time-series public dataset is used as a transfer learning dataset for the MTF time-series image encoding. The experiment demonstrates that the proposed method exhibits higher accuracy and performance than 1D-CNN and other general neural network models, and the highest accuracy rate is 98.92%.

Artisanal Watercraft Industry in Nineteenth-Century Cyprus: Vessel Types, Shipwrights, and Local Vessel Owners

ABSTRACT Recent scholarly work demonstrated that artisanal watercraft is an important aspect of Cypriot maritime culture, seaborne transport history, and trade deserving further study. A careful study of visual and historical sources allows for a discussion of this craft within its nineteenth-century setting and understanding of local market needs. A careful study of a variety of sources provides information on vessel types, local ownership, and, occasionally, the shipwrights. The Ottoman Empire’s nineteenth-century administrative inertia, combined with the fact that Cyprus was a stop along seaborne routes leading to other ports rather than a regular destination itself, impeded development of a local shipbuilding industry. Improvements on port infrastructure after Cyprus’s 1878 annexation by the British Empire initiated a modest growth but the industry never became vibrant like that of Greece. Nonetheless, analysis of the collected data illuminates previously unknown aspects of seafaring, coastal trading, and transportation. They demonstrate a cycle of choices and adaptations shaping coastal communities island-wide that are reinforced by oral testimonies of interlocutors born during the 1890s to 1920s period. Their testimonies highlight which aspects of maritime life survived in the twentieth century, such as established seaborne trade port destinations, island-wide supply networks (exchanges and trade of products), and seaborne transportation of people and goods. The data further illuminate the evolution of watercraft construction practices to meet local market demands for larger vessels (like the karavoskaro [caique]), which were bought from Greece in early to mid-nineteenth century, whereas in the late nineteenth century they were constructed locally.

ARCHAEOLOGICAL EVIDENCE OF IRON SMELTING IN BYZANTINE AND EARLY ISLAMIC JERICHO

Excavations in Jericho made it possible to reveal a notable complex of ferrous metallurgy. Archaeological evidence of iron smelting is represented by numerous slags, dozens of iron blooms, and three bloomery furnaces. They are localized mainly in the cultural layer surrounding the pottery kilns. The statistics of the finds indicate a fairly active production of iron in the Jericho workshop, where 59 small iron blooms and their fragments were found. The shape of whole blooms corresponds to a bowl-shaped depression in the lower part of small bloomery furnaces. The foundations of three similar structures were found, each of them located in the immediate vicinity of a pottery kiln. The chronology of iron production in Jericho corresponds to the time of functioning of the pottery workshop at the monastic-pilgrimage complex of the second half of the 6th – the first half of the 8th century. The archaeological context proves that ferrous metallurgy was an integral part of the production processes in the workshop throughout the entire period of its functioning. In addition, the multifunctionality of the production complex in Jericho is confirmed, which most likely provided for the vital needs of the inhabitants of a fairly large household in various types of ceramic vessels and bloomery iron throughout the late Byzantine and Umayyad periods of Palestine history.

METO-S2S: A S2S based vessel trajectory prediction method with Multiple-semantic Encoder and Type-Oriented Decoder

Vessel trajectory prediction plays a vital role in maintaining a safe and effective status in maritime transportation. The development of deep learning provides appropriate mechanisms to predict vessel trajectory using Automatic Identification System (AIS) data. However, besides limited historical position information, much information can be used to enhance deep models, including speed, course, departure time, sailing distance and vessel type. Realistically speaking, these are related to the ships’ endurance, oil storage, tide and work–rest habits. In order to address these problems, we propose a novel vessel trajectory prediction model METO-S2S based on a sequence-to-sequence structure, consisting of the Multiple-semantic Encoder and the Type-Oriented Decoder. After comprehensive data preprocessing and feature engineering, the Multiple-semantic Encoder embeds the sequential inputs of the voyage information into higher-dimensional latent vectors. In addition, the combined vector of vessel type and departure time of a particular ship is fed into the Type-Oriented Decoder treated as guidance information. To verify the efficiency and efficacy of METO-S2S, we employ an AIS dataset in US coastal waters which is more suitable for deep learning models, and implement comparative experiments with several baseline models. The experimental results show that METO-S2S is superior to them both quantitatively and qualitatively.11The code and data of our experiments is available on GitHub https://github.com/AIR-SkyForecast/METO-S2S.

Immunohistochemical visualization of lymphatic vessels in human dura mater: methodological perspectives

BackgroundDespite greatly renewed interest concerning meningeal lymphatic function over recent years, the lymphatic structures of human dura mater have been less characterized. The available information derives exclusively from autopsy specimens. This study addressed methodological aspects of immunohistochemistry for visualization and characterization of lymphatic vessels in the dura of patients.MethodsDura biopsies were obtained from the right frontal region of the patients with idiopathic normal pressure hydrocephalus (iNPH) who underwent shunt surgery as part of treatment. The dura specimens were prepared using three different methods: Paraformaldehyde (PFA) 4% (Method #1), paraformaldehyde (PFA) 0.5% (Method #2), and freeze-fixation (Method #3). They were further examined with immunohistochemistry using the lymphatic cell marker lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1), and as validation marker we used podoplanin (PDPN).ResultsThe study included 30 iNPH patients who underwent shunt surgery. The dura specimens were obtained average 16.1 ± 4.5 mm lateral to the superior sagittal sinus in the right frontal region (about 12 cm posterior to glabella). While lymphatic structures were seen in 0/7 patients using Method #1, it was found in 4/6 subjects (67%) with Method #2, while in 16/17 subjects (94%) using Method #3. To this end, we characterized three types of meningeal lymphatic vessels: (1) Lymphatic vessels in intimate contact with blood vessels. (2) Lymphatic vessels without nearby blood vessels. (3) Clusters of LYVE-1-expressing cells interspersed with blood vessels. In general, highest density of lymphatic vessels were observed towards the arachnoid membrane rather than towards the skull.ConclusionsThe visualization of meningeal lymphatic vessels in humans seems to be highly sensitive to the tissue processing method. Our observations disclosed most abundant lymphatic vessels towards the arachnoid membrane, and were seen either in close association with blood vessels or remote from blood vessels.

Evaluation of Electric Power Quality in the Ship-Integrated Electrical Power System with a Main DC Bus and Power Semiconductor Electric Drives as Part of the Electric Propulsion Complex

The relevance of the work is connected to the energy efficiency of specialized vessels of the technical fleet. The purpose of the study was to determine and evaluate the power quality indicators associated with the non-sinusoidal shape of the voltage and current curves in the electrical power system of the marine platform support vessel, which contains powerful semiconductor propulsion electric drives, taking into account the inherent and parasitic parameters of the power three-phase cable lines. A simplified one-line diagram of an electric power system with a DC main bus was the object of the study, which was compiled as a result of the analysis of analog systems typical for the indicated type of vessels. The phenomenon of voltage and current distortion caused by the presence of higher harmonics generated by power semiconductor converters in a three-phase ship network was the subject of the research. For the experimental study of the quality of electric power according to the simplified one-line scheme of the electric power system in MATLAB Simulink, its model was created. Based on the proven methods of calculating the ship’s electrical equipment, a methodology was developed for the reliable determination of model parameters. According to the results of the experiment in MATLAB Simulink, qualitative and quantitative indicators were obtained regarding the non-sinusoidality of the linear voltage and current of the three-phase network (curve shapes, amplitude spectra, distortion coefficients), and their comparative analysis with the current norms and standards was performed. In contrast to the previous ones, the methodology for assessing the quality of electricity in the studied electric power system takes into account its circuit, mode features, and the presence of a parasitic capacitance “phase to ground” of a three-phase network, and it can be used in solving similar non-trivial tasks for various similar structurally modified systems.

Behavioural responses of humpback whales (Megaptera novaeangliae) to whalewatching boats near Isla de la Plata, Machalilla National Park, Ecuador

Machalilla National Park, on the coast of mainland Ecuador, supports a growing whalewatching industry that focuses on Southern Hemisphere humpback whales, which spend the austral winter (June-September) in this area. This study was designed to measure short-term reactions of whales to the whalewatching vessel activity typically seen in this area for two reasons: (1) to identify the nature of whales’ avoidance response, if any, in order to draft whalewatching guidelines that help local mariners identify when they may be disturbing whales; and (2) to quantify the magnitude of any avoidance response, to examine how this relatively understudied population behaves around boats compared with whales in other whalewatching areas. A shore-based theodolite tracking team created a ‘natural’ experiment to observe relationships between whalewatching traffic and whale behaviour in 1998 and 1999. Swim speed and path directness of humpback whales were measured in the absence of boats, and how those parameters changed when boats arrived was recorded. When whales entered the study area accompanied by boats, a record was made of how their behaviour changed after the boats left. Humpback whales reacted to the approach of whalewatching boats by increasing swim speed significantly, and adopted a much more direct path after boats left. Future research is needed to determine whether responses vary with number, proximity or type of vessel. Similarly, future studies are recommended to determine whether different age-sex classes vary in vulnerability to disturbance. Meanwhile, this study enables provision of much-needed, practical advice to local operators who are concerned that they may be disturbing whales: one way that mariners can tell if they are causing disturbance is if they need to increase their vessel’s speed to keep pace. The average behavioural responses measured were strong enough to recommend that Machalilla National Park adopt precautionary management procedures to limit number and proximity of vessels.

Holistic and sustainable design optimization of Arctic ships

This paper reviews challenges of relevance to the future development of Arctic sustainable shipping by considering future demands for vessel types, available alternative energy sources, and novel technologies. Results reveal the need to extend existing concept ship design methods to account for the holistic yet sustainable design of Arctic vessels. Accordingly, the paper introduces a decision support framework for holistic and sustainable optimization of the concept design of Arctic ships for different cold regions and purposes of operation. The method presented simultaneously accounts for eco-efficiency, cost-efficiency, and safety. Demonstration for the case of a battery-driven Arctic offshore wind farm service and offshore support vessels shows that optimized designs could outperform their existing environmentally and economically efficient counterparts.

Validation and efficacy of 'pure' venous lymph node flap in a rat lymphoedema model.

The venous lymph node flap (vLNF) is regarded as an arterialized or 'pure' venous flap, subject to which type of vessel provides blood supply to the flap. However, whether the vLNF drainage function is maintainable or sufficient for the treatment of lymphoedema is yet to be elucidated. In this study, the venous flow-through lymph node flaps or 'pure' vLNF was investigated in a rat's tail (lymphoedema model), and the therapeutic effect was analysed to clarify its potential value for the treatment of lymphoedema. The subjects (rats) were divided into three groups, the experimental group ('pure' vLNF group), the control group (lymphoedema group), and the baseline group. The tail circumference and diameter were recorded for 5 weeks after the operation. Five weeks after surgery, the lymphatic drainage function was evaluated using indocyanine green (ICG) lymphography, while the skin thickness and collagen layer were assessed by histological analysis. The average diameter and circumference of the experimental group were significantly shorter than the control group (p < 0.01). When comparing ICG lymphography within the three groups, the baseline group showed that the ICG entered the inguinal lymph node and appeared in the liver while the ICG still accumulated in the oedematous tail with no fluorescence emerging in other parts of the rat's body, in the control group. In the experimental group, the ICG entered the vLNF via the flap junction with the rat's tail and fluorescence emerging in the rat's liver. When comparing the three groups above with the control group, the experimental group's skin and collagen layer thickness were significantly improved (p < 0.01). Lymphatic recanalization was shown to appear between 'pure' vLNF and the recipient area. Moreover, vLNF was shown to drain lymph fluid via the venous system, thus relieved swelling and fibrosis of the lymphoedematous tissue. Consequently, this could represent a new potential surgical approach for the treatment of lymphoedema.

:Ausgrabungen in der frühbronzezeitlichen Siedlung im Heraion von Samos 1966

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Xylem vessel type and structure influence the water transport characteristics of Panax notoginseng.

Panax notoginseng plays a very important role in medicinal and economic value. The restriction imposed by the hydraulic pathway is considered to be the main limitation on the optimal growth state of Panax notoginseng. The flow resistance and water transport efficiency of vessel were affected by vessel type and secondary thickening structure. The vessel structure parameters of Panax notoginseng were obtained by experimental anatomy, and the flow resistance characteristics were analyzed by numerical simulation. The results showed that the xylem vessels had annular thickening and pit thickening walls. The flow resistance coefficient (ξ) of the pitted thickening vessel was significantly lower than that of annular thickening vessel in four cross-sectional types. The ξ of the circular cross-sectional vessel was the largest, followed by the hexagon, pentagon cross-sectional vessel and the lowest was the quadrilateral cross-sectional vessel, and the structure coefficient (S) was just the opposite. The ξ of the vessel model was positively correlated with the annular height, pitted width and pitted height, and negatively correlated with the annular inscribed circle diameter, annular width, annular spacing, pitted inscribed circle diameter and pitted spacing. Among them, annular (pitted) height and the annular (pitted) inscribed circle diameter had a great influence on the ξ. The increasing and decreasing trend of the S and ξ were opposite in the change of annular (pitted) inscribed circle diameter, and consistent in the change of in other structural parameters, indicating that the secondary wall thickening structure limited the inner diameter of the vessel to maintain a balance between flow resistance and transport efficiency.

Prioritizing management of high-risk routes and ports by vessel type to improve marine biosecurity efforts

The shipping industry constitutes the main vector of marine bioinvasions. Over 90,000 vessels world-wide create a highly complex shipping network that requires appropriate management tools. Here we characterized a novel vessel category, Ultra Large Container Vessels (ULCV), in terms of potential contribution to the dispersal of Non-Indigenous Species (NIS) in comparison to smaller vessels traveling similar routes. Such approach is essential for providing precise information-based risk analysis necessary to enforce biosecurity regulations and reduce the adverse global effects of marine NIS. We used Automatic Identification System (AIS) based websites to extract shipping data that will enable us to test for differences in two vessel behaviors linked to NIS dispersal: port visit durations and voyage sailing times. We then examined the geographic spread of ULCVs and small vessels, quantifying the accumulation of new port visits, countries, and ecoregions for each vessel category. Finally, Higher Order Network (HON) analysis revealed emergent patterns within shipping traffic, species flow, and invasion risk networks of these two categories. Compared to the smaller vessels, ULCVs spent significantly longer time in 20% of the ports and were more geographically constrained, with fewer port visits, countries, and regions. HON analysis revealed that the ULCV shipping species flow and invasion risk networks were more similar to each other than to those of the smaller vessels. However, HON port importance shifts were discernible for both vessel categories, with major shipping hubs not necessarily being major invasion hubs. Overall, compared to smaller vessels, ULCVs behave differently in ways that potentially increase biofouling risk, albeit in a smaller set of ports. Future studies using HON analysis of other dispersal vectors appears critical for prioritizing management of high-risk routes and ports.

A Multipurpose and Power Quality Improved Electric Vessels Charging Station for the Seaports

To avoid air and noise pollution on seaports, the use of electric vessels and shore-to-ship power supply based charging station on seaports are in trend, which is also known as cold ironing (CI) infrastructure. In the starting stage, electric vessels charging stations are being implemented on the most busiest commercial ports, where modern electronic devices are used to serve different types of vessels. These devices only take care of the quality of output power. However, on the input side, it creates a serious harmonic issue. During CI, megawatt range of power is supplied to the ships, so generated harmonics and interharmonics in the high-power supply based charging system become more dangerous for the grid. In this article, we propose a novel power quality improved cold ironing (PQICI) system (charging mechanism) to overcome this issue. Moreover, due to inherent multipurpose useability, this novel PQICI is able to supply different types of power to various types of vessels, such as ac power, dc power, 50 Hz frequency, 60 Hz frequency, single phase, three phases, three-wire network, four-wire network, five-wire network, and different ac and dc voltages. Furthermore, this PQICI supply system is capable of serving four vessels at a time. In every type of loading condition with different kinds of power supply mode, the PQICI maintains the power quality on the input side, with fulfilling the varieties of the power demand of vessels. The capability of the developed “PQICI” system is tested for different types of ships and vessels on the simulation platform as well as through real-time hardware-in-the-loop experimentation. On IEEE standard 519, satisfactory test results on both platforms show the efficiency of the developed system and its control mechanism.

Prediction of ship domain on coastal waters by using AIS data

Ship domain is crucial for collision risk assessments and may vary depending on the navigation area. In this study, an empirical ship domain model for coastal waters is proposed. The proposed ship domain model is planned to reveal the ship domain model for an area where no traffic separation scheme exists. In the study, dodecagon ship domain for different type and size of vessels was created. One-year (11 month) of vessel encounters were analyzed and ship domain boundaries are prepared by considering different safety criteria. The passages of the vessel from forward, aft, port, and starboard were also statistically analyzed and the changes in ship domain dimensions according to the ship type and size are revealed. This model shows the vessels behavior regardless of traffic separation rules.

Otras formas de demencia: demencia vascular, demencia con cuerpos de Lewy y demencia frontotemporal

Vascular dementia is the second cause of dementia after Alzheimer's disease. It is a heterogeneous entity with highly variable symptoms based on the location of vascular damage and the type of vessel affected. It is classified as multi-infarct dementia, subcortical dementia, and strategic infarct dementia. Lewy body dementia is the second most common degenerative dementia and is characterized by cognitive impairment with parkinsonism that does not respond well to treatment, fluctuations in level of consciousness and cognition, hallucinations, and hypersensitivity to neuroleptics. Frontotemporal dementia is most common in those younger than 60 years. The behavioral variant is the most frequent and is characterized by inappropriate social behavior, lack of inhibition, personality disorder, apathy, and eating disorders. The second group comprises progressive primary aphasia which, in turn, has a nonfluent variant and a semantic variant. Lastly, included in the group of frontotemporal dementia is progressive supranuclear paralysis and corticobasal degeneration, given that together with parkinsonism, they tend to entail cognitive disorder in the behavioral variant or primary progressive aphasia.

Collateral circulation develops in stenosis of the celiac trunk and superior mesenteric artery.

Mesenteric circulation is provided by the celiac trunk (CT), superior mesenteric artery (SMA), and inferior mesenteric artery (IMA). The collateral circulation between CT and SMA and between SMA and IMA plays a protective role against intestinal ischemia in case of narrowing or occlusion of the mesenteric vessels. In our study, it is aimed to determine the CT and SMA stenosis rates in patients with CT and SMA stenosis from angiography images, the occurrence of the collateral variations, and the frequency of these variations. A total of 408 non-selective or selective CT and SMA angiographic images were taken of 215 patients (130 males, 85 females) who were admitted to Akdeniz University Hospital with symptoms of chronic mesenteric ischemia (CMI) were included. The angiography images were analyzed in regards to CT and SMA stenosis rates, and the collateral variations between mesenteric vessels. Stenosis of CT was observed in 14 patients, whereas the stenosis of the SMA was observed in 12 patients. The most common collateral vessel in these patients was the gastroduodenal artery. Both stenoses of CT and SMA were found in 9 patients. The Riolan arch was the most common type of collateral vessel in these patients. It was observed that mesenteric circulation was mainly provided by gastroduodenal artery in patients with isolated CT or SMA stenosis or occlusion while in patients with stenosis or occlusion of both CT and SMA, mesenteric circulation was mainly provided by the Riolan arch. A significant increase was observed in the prominence of collateral vessels in patients with stenosis of more than 70%.

Development of short sea shipping in the north coast of Java Island, Indonesia as a potential market

The island of Java is the smallest of the six major islands in Indonesia. It is, however, the centre of national economic activity because 75% of industrial areas are located on this island, accounting for 59% of the national gross domestic product. The movement of goods on the island of Java reached 160.5 million tons, with trucks accounting for 90.3% of the total, contributing to traffic congestion. The ratio of road capacity to traffic volume on various major roads reached 1.3. This study aims to investigate how to reduce this ratio to 0.8 on the roads of Java by developing a short sea shipping transportation route from Jakarta to Surabaya. This study has never been conducted by the Ministry of Transportation of the Republic of Indonesia. According to the findings of the study, the potential cargo for short sea shipping reached 3.98 million twenty-foot equivalent units (TEUs). One of the most suitable types of vessels to be developed is the motorised container barge (MCB), which could operate on 88 voyages per year and have a capacity of 900 or 1,000 TEUs. The freight rate for short sea shipping ranges from $ 447 to $ 458 per TEUs, resulting in a benefit-cost ratio of 1.5 at a load factor of 70%. The freight rate is less expensive than the truck freight rate after adding the cost of trucking to and from the hinterland.

Collisions of sailing vessels with cetaceans worldwide: First insights into a seemingly growing problem

Vessel-whale collisions are of growing concern worldwide, but information about collisions involving sailing vessels is especially scarce. This study represents the first global quantification of this kind. A total of 111 collisions and 57 near misses were identified, spanning from 1966 until 2010; 75% of cases was reported for the period from 2002–2010, suggesting an increasing trend. Reported collisions and near misses occurred on all oceans, often during ocean races and regattas, and were most frequent in the North Atlantic. Vessel type and speed as well as circumstances of the incident varied widely, but most often monohulls were involved, predominantly sailing at speeds between 5 and 10 knots. Most reports referred to ‘large whales’ as opposed to ‘small whales’ or ‘dolphins’. The species could be identified in 54 cases. Most recognised animals were humpback or sperm whales. Injuries to the whales varied strongly from ‘not visible’ to ‘dead after collision’, but mostly could not be determined. Sailing crew members were hurt in several cases, including collisions occurring at low speeds, and collisions often damaged vessels, including major impairment and seven cases of vessel loss. The findings presented here suggest that elevated vessel speed contributes to a higher risk of collisions. Conversely, the outcome of a collision (e.g. injury to whale or crew, damage to vessel) appears not to be a direct function of vessel speed. Several measures are discussed which potentially can contribute to mitigating the problem, including placing watchposts, an open dialogue with regatta organisers, changes in the design of regattas and ocean races and public outreach initiatives.

Numerical Analysis on Added Resistance of a Crew Boat with Variation of Wave Period

Crew boat is a type of vessels used for the mobility of offshore workers and logistical supply needed for the offshore platform. Crew boat KCT-1901 is categorized as a planning boat with hard chine body. KCT-1901 requires an added power when it is sailing through a seaway. The reason behind this is because when a ship sails through a seaway, the ships experienced a heave and pitch motion resulted in added resistance and hence added power. The goal of the investigation is to estimate added resistance and added power of the crew boat using computational fluid dynamic (CFD) method and tested in calm water and in waves with several Froude numbers (Fr) and wave periods. A method developed by Savitsky is used for verification at high-speed mode. The largest total resistance using CFD in calm water is 38.98 kN and using Savitsky method is 39.00 kN obtained at Fr 0.72. Both are in good agreement and the discrepancy is less than 0.1%. Comparative study was carried out against experimental test in a towing tank. The drag forces tested at Fr 0.12 and 0.24, between the two approaches, showed a discrepancy of about 4%. Further CFD test was conducted on wave pattern analysis, which demonstrated that as the Fr increases the becomes clearer and stronger and tests in waves condition at lower wave period showed that the transverse wave becomes more apparent. Therefore, overall can be said that the CFD simulation showed such a good agreement with empirical Savitsky method and experimental tank test.

Trends in collisions between vessels and North Pacific humpback whales (Megaptera novaeangliae) in Hawaiian waters (1975–2011)

Injury from collisions with vessels is a growing threat worldwide for many species of whales. Thirty seven years of historical records were examined for evidence of vessel collisions with humpback whales in the main Hawaiian Islands. Between 1975 and 2011, 68 collisions between vessels and whales were reported including 59 witnessed collisions and 9 observed whale injuries that were consistent with a recent vessel collision. No collisions were immediately lethal. The waters between Maui, Molokai, Lanai and Kahoolawe, which are known to have one of the highest concentrations of humpback whales in the Hawaiian Islands, had the highest incidence of collisions. Over 63% of the collisions involved calves and subadults, suggesting a greater susceptability towards collisions among younger animals. The rate of collisions increased significantly over the final twelve breeding seasons of the study and was greater than predicted by the estimated annual increase in the whale population, suggesting that the rising number of reported collisions cannot be explained solely by the annual increase in whale abundance. Although the total number of registered vessels and shipping traffic in Hawaii remained relatively constant between 2000 and 2010, there was a significant increase in the number of vessels between 7.9m and 19.8m in length. Vessels within this size range were also the most commonly involved in collisions during the study period, accounting for approximately two thirds of recorded incidents. It is concluded that from 1975–2011, there was a significant increase in reports of non-lethal collisions between vessels and humpback whales, especially calves and subadults, in the main Hawaiian Islands that likely reflects a combination of factors including the recovery of the population of North Pacific humpback whales, increases in traffic of particular vessel types, and increased reporting practices by operators of vessels.