Vessel Speed Research Articles

Dynamic strategies offer potential to reduce lethal ship collisions with large whales under changing climate conditions

Dynamic ocean management (DOM), a type of marine spatial planning in which management decisions are updated in response to changing environmental, biological, or socioeconomic conditions, holds promise for balancing tradeoffs between conservation and marine resource use. However, as climate change continues to drive unprecedented oceanic changes, it is critical to evaluate how such tradeoffs may vary under different environmental regimes to ensure management strategies remain robust. To address this need, we explored blue whale ship strike management scenarios in the Southern California Bight, USA, an area that currently uses voluntary vessel speed reductions to mitigate risk of lethal ship collisions. We compared two simulated DOM strategies – a ‘daily strategy’ that implemented speed reductions in response to whale habitat conditions on a daily basis, and a ‘seasonal strategy’ that implemented speed reductions in response to whale habitat conditions on a seasonal basis – with a ‘fixed strategy’ that implemented speed reductions for a fixed time period each year, irrespective of environmental conditions. We evaluated the capacity of these strategies to balance tradeoffs between whale conservation and shipping activities over a 17-year study period. Critically, we assessed these tradeoffs before, during, and after a record marine heatwave to evaluate the relative utilities of these strategies during anomalous ocean conditions. Over the 17-year study period, seasonal and daily DOM strategies achieved a 6.4–10.7% improvement in expected whale protection from lethal collision, respectively, without the need for additional vessel speed reductions, as compared to the fixed strategy. The benefit of DOM strategies has grown in the last decade and was accentuated during and after the marine heatwave event, with the daily DOM strategy seeing a 16.2% increase in whale protection compared to the fixed strategy in the five years prior to the event, versus a 26.5% increase in the five years during and after the event. Such results indicate that dynamic ocean management is a valuable strategy for coping with anomalous environmental conditions, which will become increasingly important as the climate continues to change. Moreover, our study emphasizes the importance of assessing tradeoffs between conservation goals and human activities over a range of environmental conditions in order to evaluate the robustness of management strategies to climate change.

Making sense of speed effects on ice crushing pressure-area relationships in IACS ice-strengthening rules for ships

Arctic shipping fleet expansion is anticipated in the future. However, future refinements in the understanding of ice loads on larger ships are needed to achieve a better structural design with reduced steel weight. Published rules for the strength of ships are derived from semi-empirical methods and calibrated with limited full-scale measurements on small ships. In 2015, the Lloyd's Register pointed out that for independent navigation of larger ships in heavier ice conditions, steel weight increases exponentially with the ice thickness, which negatively affects the economy of ships' operations.Motivated by this statement, the objective of this paper is to address uncertainty in rule-derived ice loads using an ice mechanics point of view. The focus is on the local ice crushing loads and the vessel speeds in the Unified Requirements for Polar Class Ships of the International Association of Classification Societies (IACS).In this work, we attempt to relate the IACS speed-dependent ice pressure-area relationships to the simplified principles of ice mechanics coupled with structural design considerations. This relation enables us to better understand uncertainties in the rule loads for larger ships, which is essential to address the economy of Arctic ships’ operations. The results of this study showed that the choice of parameters in IACS ice crushing loads for larger vessels with higher ice classes (PC1) has high uncertainty and the upper limit values are greater than those predicted by the ice mechanics approach.

Relationship between purse seine dimensions and catch volume in Sikka Regency, Indonesia

The purse seine is a very productive fishing gear for small pelagic fishes. For purse seines that are actively operated during the day-time, the dimensions of the purse seine are expected to be closely related to the number of fish caught. Field conditions indicate that fishermen use purse seines of varying dimensions. In this context, research is needed. This study aimed to analyze the relationship between purse seine dimensions and the volume of fish caught. This research was conducted in the waters of Sikka Regency, East Nusa Tenggara Province, Indonesia from November to December 2019. The parameters observed included purse seine dimensions, vessel speed and the volume of fish captured per trip. The results showed that purse seine dimensions had a very weak positive correlation (r = 0.088) with catch volume. This shows that the relationship between purse seine dimensions and the volume of fish caught is very weak. Most likely the differences in catch volume were caused by other factors. This is in contrast with other studies showing a significant relationship between the dimensions of the purse seine and the volume of fish caught. In the research location the fishing ground was heavily used, so that the fishing vessels were operating relatively close to one another. This may have created conditions where the net dimensions played a lesser role in increasing the volume of fish caught. In order to avoid one purse seiner being affected by the activities of another purse seiner, it would be necessary to expand the fishing ground or reduce the number of purse seiners operating in that particular fishing ground.

Transportation efficiency in eighteenth-century merchant vessels

A key ingredient in New England’s shipping successes was the speed with which its vessels completed their voyages. The principle research on this subject was completed by Gary Walton and published in its first form in 1967. Walton was ahead of his time in identifying the importance of a detailed study of colonial shipping and linking it to a broader Atlantic World. He draws several conclusions. First, that technological change between 1675 and 1775 was minimal in the industry. Second, costs and crew sizes declined due to increases in security after the Royal Navy eliminated piracy. Third, idle time in port decreased, leading to more efficiencies in acquiring cargo. Fourth, and finally, vessel speeds were stagnant throughout the period and were 1.6 to 1.97 knots for the voyage south between New England and the West Indies and 1.31 to 2.09 knots for the return trip. Averages calculated by Walton indicate speeds of between 1.6 and 1.8 knots, with the southbound legs slightly faster. I agree with Walton on all of his conclusions except for the last. Careful study of 145 logbooks chronicling the voyages of Massachusetts’s vessels in the West Indies trade indicates that the median vessel speed over the approximately 1,500 nautical miles from Boston to the islands was 2.71 knots and the mean speed approached 2.84 knots. In fact, the median southbound speed was five per cent slower than the trip home. In practical terms, this meant that according to Walton the time it took to travel 1,500 nautical miles averaged a minimum of almost 35 days. According to the logbooks, however, merchant mariners completed voyages between New England and the West Indies in slightly more than 25 days on average, 28 per cent faster than Walton figured.

Effects of a Vessel Speed Reduction Program on Air Quality in Port Areas: Focusing on the Big Three Ports in South Korea

As the seriousness of air pollution from ports and ships is recognized, the Korean Port Authority is implementing many policies and instruments to reduce air pollution in port areas. This study aims to verify the effects of the vessel speed reduction (VSR) program among the procedures related to air pollution in port areas. This study was conducted using panel data created by combining ship entry and departure data and air quality measurement data. We measured the changes in air quality according to the entry and departure of ships and examined whether it changes due to the VSR program. For estimation, the panel fixed-effect model and the ordinary least squares (OLS) model were used. The results suggest that the VSR program had a positive effect on improving air quality in port areas. However, the VSR program’s effects were different over ports. Busan Port showed the highest policy effect, and Incheon Port showed a relatively low policy effect. Based on the results of this study, to maximize the VSR program’s effectiveness at the port, it is necessary to implement other eco-friendly policies as well.

Bottom-Up Approach Ship Emission Inventory in Port of Incheon Based on VTS Data

As a result of the rapid growth of international trade, atmospheric pollution from transportation has been more topical than ever, especially in dense hub port-cities. The shipping industry should pay more attention corresponding to its contribution to local atmospheric pollution. This paper supports the application of data collected from the vessel tracking service system with a bottom-up approach to generate a comprehensive 2019 local ship emission inventory at Port of Incheon. The calculated emission inventory presented the dominance of CO2 emission and the considerable contribution of NOx and SOx emissions, the significant contribution of auxiliary engines during the hotelling at berth during the year of 2019. Then, based on calculated emission inventory, this study suggested and simulated applicable green policies in the practice: (1) local emission control area realization, (2) vessel speed reduction program, (3) application of cold ironing, and (4) establishment of a national integrated emission platform. The combination of the three first policies could help reduce the significant volume of emitted CO (29%), NOx (30%), SOx (93%), PM10 and PM2.5 (64%), VOC (28%), NH3 (30%), and CO2 (30%).

Feasibility of the Northeast Passage: The role of vessel speed, route planning, and icebreaking assistance determined by sea-ice conditions for the container shipping market during 2020–2030

This study aims to examine the feasibility of the Northeast Passage for container transportation during the period of 2020–2030. A novel model is developed to study the impact of sea-ice conditions on freight rate between the Northeast Passage and Suez Canal Route on a round voyage. The sea-ice concentration and thickness are treated as key factors controlling the use of icebreakers, operational speed, and route planning in the model. Freight rates, shipowner profits, and consumer demands on both routes are determined as model outputs. Three scenarios in 2020, 2025 and 2030 respectively are used to test the model.

Spatial–temporal variations in biosonar activity of Yangtze finless porpoise in the lower reaches of the Yangtze River and its correlation with underwater noise: Are quieter non‐shipping branches the remaining shelters?

Abstract Yangtze finless porpoise (YFP) is Critically Endangered, It relies on its biological sonar sensing system for important life activities. The rapid development of the Yangtze valley has brought busy shipping, which has resulted in increased noise. Two locations on the shipping channel and non‐shipping branch were selected. Passive acoustic monitoring was used to record the biosonar signals of porpoises and underwater noise. The number of click trains, echolocation encounters, buzzes and buzz ratios were counted and the root mean square sound pressure level of noise was calculated in five diel phases. A non‐parametric test was used to analyse the differences among different phases and between different locations. The aim of the study was to detect the spatial and temporal variations in the biosonar activity of YFPs and underwater noise between non‐shipping and shipping channels, and to provide scientific advice for YFP conservation. Significant spatial and temporal patterns were observed both in biosonar activity and noise. Average biosonar activity, including click trains, buzzes, buzz ratio and echolocation encounters, was higher in the non‐shipping channel than in the shipping channel, whereas the noise level was higher in the shipping channel than in the non‐shipping channel. In the non‐shipping channel, the buzz numbers and buzz ratios, indicators of porpoise feeding activity, were higher at night than during the day while the noise level was higher during the day than at night. These findings may be associated with the noise avoidance strategies of YFPs to adapt to the busy shipping on the Yangtze River. Maintaining the non‐shipping status of some branches of the Yangtze River can provide more shelters for the YFPs. Strengthening the measures for banning navigation at night or reducing the vessel speed at night throughout the entire year would improve the YFPs’ feeding success.

Improving hydroacoustic sampling in large rivers: Evaluating factors influencing target detectability

AbstractMobile hydroacoustic sampling is increasingly being used to monitor fish populations in large rivers; however, several factors may influence the ability to sample fishes with this gear in these environments. This study sought to address the effects of vessel speed, wind speed, the coefficient of variation (CV) of transducer pitch angle, and beam compensation (BC) on hydroacoustic detectability to advance and inform mobile, horizontally oriented hydroacoustic sampling in large rivers. A series of four replicate surveys was conducted past 23 artificial targets at three vessel speeds in a large river. Wind speed data during surveys were obtained, and post‐processing of hydroacoustic data was conducted separately under maximum BC values of 6 and 12 dB. Results revealed significant negative effects of wind speed and transducer pitch CV on buoy detectability, as well as negative interactions between vessel speed and wind speed, with detectability decreasing as wind speed increased, particularly at slower vessel speeds. We suggest this may be due to increased vessel and transducer motion during periods of increased wind speed. Detectability also significantly increased under an expanded BC due to a greater proportion of the water volume being analyzed; however, further work is necessary before implementing greater BC settings in large rivers. These results ultimately display the interactive and negative effects of wind speed and vessel speed on horizontal hydroacoustic detectability in large rivers, revealing important considerations for hydroacoustic monitoring and sampling efforts in these systems.

Reanalysis of the Sydney Harbor RiverCat Ferry

In this paper, we revisit the hydrodynamics supporting the design and development of the RiverCat class of catamaran ferries operating in Sydney Harbor since 1991. More advanced software is used here. This software accounts for the hydrodynamics of the transom demisterns that experience partial or full ventilation, depending on the vessel speed. This ventilation gives rise to the hydrostatic drag, which adds to the total drag of the vessel. The presence of the transom also creates a hollow in the water. This hollow causes an effective hydrodynamic lengthening of the vessel, which leads to a reduction in the wave resistance. Hence, a detailed analysis is required in order to optimize the size of the transom. It is demonstrated that the drag of the vessel and the wave generation can be predicted with good accuracy. Finally, the software is also used to optimize the vessel further by means of affine transformations of the hull geometry.

Sensitivity analysis of process parameters for granular mixing in an intensive mixer using response surface methodology

Discrete element method (DEM) has been used to study the effect of process parameters, filling ratio, impeller speed, and vessel speed, on granular mixing performance in an intensive mixer. Their effects were evaluated in terms of coordination number (CN), relative standard deviation at a specified time (RSDT) and relative standard deviation at a specified input work (RSDIW). Analysis of variance (ANOVA) and response surface method (RSM) were employed to study the significance analysis of the individual factor effects and factor combination. The results of experiments indicate that CN and RSDT increase with the increase of filling rate and the decrease of impeller speed, and RSDIW increases with the increase of filling rate, while the influence of vessel speed and impeller speed on RSDIW is dependent on the other two parameters of mixer. Additionally, filling rate, impeller speed and vessel speed showed interactive effects on all presented responses.

Navigational risk analysis based on GIS spatiotemporal trajectory mining: a case study in Nanjing Yangtze River Bridge waters

With the continuous growth of the quantity, scale, and speed of vessels in recent years, maritime accidents are posing increasing risks to societies and individuals, especially in narrow inland waterways. Therefore, it is of great significance to analyze navigational risks to ensure the safety of waterborne transportation. In this paper, the navigational risks of Nanjing Yangtze River Bridge (NYRB) waters are investigated based on spatiotemporal mining on massive automatic identification system (AIS) trajectories by using geographic information system (GIS) techniques. A time-series-oriented trajectory processing method is proposed to deal with the historical AIS data in the whole year of 2019. The method adopts a periodic processing strategy to produce traffic density estimation products in multiple temporal scales for supporting spatiotemporal analysis. The proposed method greatly improves the data-processing efficiency and provides a flexible way to deeply understand the vessel behavior patterns in NYRB waters. Then the complete characteristics of the spatial distribution and temporal variation of AIS trajectories are revealed. Based on that, three types of critical navigational risks are discovered, which include the safety distance risk, the pier collision risk, and the traffic congestion risk. Moreover, we find that the greatest risk is existed in small vessels in the flood season, which is worth the most concern.

DEM simulation of binary mixing particles with different density in an intensive mixer

DEM simulations of binary mixing of particles with different densities were conducted to study the influence of density ratio, impeller speed, and vessel speed on the particle dynamics and mixing performance in an intensive mixer. Six particles at different locations were tagged to discuss the influence of three factors on the particle trajectory and residence time in the impeller influence area. Velocity profile at a fixed point was analyzed to explore the local phenomena. Mean velocity fluctuation, coordination number and relative standard deviation (RSD) were used to quantify the mixing performance in the mixing process. It was found that the residence time increases with the increase of particle density, and the mean velocity fluctuation increases with the increase of impeller speed. The trajectory radius in impeller influence area and the vertical movement increase with the increase of impeller speed. Results obtained indicate that the mixing performance of binary particles with different density increases with the increase of impeller speed and vessel speed, while it decreases with the increase of density ratio.

Ambient marine shipping emissions determined by vessel operation mode along the East China Sea

Marine shipping emissions exert important air quality and climate impacts. This study characterized the ambient pollutants predominant by emissions from a variety of marine vessel types near the mid-latitude East China Sea. Two discernible primary shipping emissions were identified by factorization analysis on detailed mass spectra of organic aerosol (OA), as emissions in maneuvering and cruise, highly linked with NOx (and less oxidized OA, black carbon, BC) or CO (and more oxidized OA), respectively. Using radio-recorded quantities and activities of 3566 vessels mixed with slow and high-speed diesel engines, we found emission of NOx or BC per vessel was positively correlated with vessel speed, while CO emission peaked at moderate speed. The approach here based on vessel operation mode directly linked the vessel activities to ambient concentrations of pollutants from marine shipping emission, and may synthesize the complex vessel types in shipping emission inventory.

Visual Appearance of Oil on the Sea

The visual appearance of oil spills at sea is often used as an indicator of spilled oil properties, state and slick thickness. These appearances and the oil properties that are associated with them are reviewed in this paper. The appearance of oil spills is an estimator of thickness of thin oil slicks, thinner than a rainbow sheen (<3 µm). Rainbow sheens have a strong physical explanation. Thicker oil slicks (e.g., >3 µm) are not correlated with a given oil appearance. At one time, the appearance of surface discharges from ships was thought to be correlated with discharge rate and vessel speed; however, this approach is now known to be incorrect. Oil on the sea can sometimes form water-in-oil emulsions, dependent on the properties of the oil, and these are often reddish in color. These can be detected visually, providing useful information on the state of the oil. Oil-in-water emulsions can be seen as a coffee-colored cloud below the water surface. Other information gleaned from the oil appearance includes coverage and distribution on the surface.

A joint liner ship path, speed and deployment problem under emission reduction measures

This paper addresses a joint ship path, speed, and deployment problem in a liner shipping company considering three emission reduction measures, including sulfur emission regulations, carbon tax, and vessel speed reduction incentive programs (VSRIPs). Given a set of service routes and the total number of available ships, the proposed problem determines how many ships should be deployed on each route and how to design sailing path and speed for each leg. A mixed-integer non-linear programming model is presented for minimizing the total cost of all routes, i.e., fuel cost, carbon tax, and fixed cost, minus dockage refund. The different impacts of the three emission reduction measures on sailing path and speed complicate the problem. Some important properties are obtained by analyzing the proposed model. Combining these properties with a dynamic programming approach, a tailored method is developed to solve the problem. Based on real data, extensive numerical experiments are conducted to examine the validity of the proposed model and the efficiency of the solution method. The computational results demonstrate that the proposed model can contribute to significant cost savings for shipping companies.

An Energy Consumption Approach to Estimate Air Emission Reductions in Container Shipping

Container shipping is the largest producer of emissions within the maritime shipping industry. Hence, measures have been designed and implemented to reduce ship emission levels. IMO’s MARPOL Annex VI, with its future plan of applying Tier III requirements, the Energy Efficiency Design Index for new ships, and the Ship Energy Efficiency Management Plan for all ships. To assist policy formulation and follow-up, this study applies an energy consumption approach to estimate container ship emissions. The volumes of sulphur oxide (SOx), nitrous oxide (NOx), particulate matter (PM), and carbon dioxide (CO2) emitted from container ships are estimated using 2018 datasets on container shipping and average vessel speed records generated via AIS. Furthermore, the estimated reductions in SOx, NOx, PM, and CO2 are mapped for 2020. The empirical analysis demonstrates that the energy consumption approach is a valuable method to estimate ongoing emission reductions on a continuous basis and to fill data gaps where needed, as the latest worldwide container shipping emissions records date back to 2015. The presented analysis supports early-stage detection of environmental impacts in container shipping and helps to determine in which areas the greatest potential for emission reductions can be found.

Predicting vessel speed in the Arctic without knowing ice conditions using AIS data and decision trees

The vessel speed is one of the important parameters that govern safety, emergency, and transport planning in the Arctic. While previous studies have traditionally relied on physics-based simulations to predict vessel's speed in ice-covered waters, most have not fully explored data-driven approaches and powerful supervised machine learning tools to aid speed prediction. This study offers a perspective of applying supervised machine learning models to predict MV SOG using historical Automatic Identification System (AIS) data and without explicit knowledge of local ice conditions. This paper presents a case-study from the region of the Eastern Barents Sea and the Southern Kara Sea. We first analyzed the vessel traffic situation for the years 2017 and 2018, and then used this knowledge to build statistical models to predict vessel speeds. Finally, we evaluated the models’ performance on a test dataset from January 2019. Performance of three models (Random Forest, XGBoost, and LightGBM) have been tested with a variety of date-time handling techniques, and data input mode being permuted to arrive at the most optimal model. The results demonstrate the ability of the models to predict the vessel's speed based on its geographical location, time of the year and other engineered features such as daylight information and route. With the proposed approach we were able to achieve mean absolute error 3.5 knots in average on a test dataset without explicit knowledge of local ice conditions around the vessel, with the majority of the errors being in the Kara Strait region and the Sabetta Channel.

Vessel Velocity Estimation and Tracking From Doppler Echoes of T/R-R Composite Compact HFSWR

Vessel speed and heading are two important kinematic parameters describing its state of motion. However, due to low spatial resolution of a compact high-frequency surface wave radar (HFSWR), vessel speed and heading cannot always be accurately estimated. Since HFSWR can measure vessel Doppler velocity with relatively high accuracy, it is possible to estimate a vessel's vector velocity based on two Doppler velocities measured along two different directions. In this article, a newly developed T/R-R composite compact HFSWR system is introduced, and a corresponding vessel velocity estimation method which employs a target's radial velocity and elliptical velocity, respectively, measured by the monostatic (T/R) and bistatic (T-R) settings is proposed. First, monostatic and bistatic tracks are independently generated using a multitarget tracking algorithm. Then, the obtained monostatic and bistatic tracks are matched using a track-to-track association method to determine the track pair belonging to each target. Subsequently, the associated track pairs are combined to produce fused tracks for improving positioning accuracy. Finally, vessel vector velocity is estimated based on the radial and elliptical velocities as well as the fused target position. Comparisons of vector velocity estimation results from radar field data with corresponding automatic identification system data demonstrate that the average root-mean-square-errors of the estimated speed and heading are 0.48 km/h and 3.9 $^{\circ }$ , respectively, which meets the practical requirements of a maritime surveillance system. Moreover, the velocity estimation error is analyzed via theoretical derivation and experimental verification. The proposed method shows good potential in further improving the tracking accuracy.

КОМЕРЦІЙНІ РИЗИКИ В СИСТЕМІ МОРСЬКИХ ПЕРЕВЕЗЕНЬ НА ПРИКЛАДІ КОНТЕЙНЕРОВОЗУ «EVER GIVEN»

Every year there is an intensive increase in tonnage and operational speed of vessels in the competition to improve the quality of transport and logistics services. Ship management needs to work in difficult, sometimes extreme conditions. It is necessary to comply with the commercial conditions of charters and not to violate the terms of delivery, to ensure the proper quality of cargo on board the vessel, as well as to comply with the conditions of safety of navigation in difficult weather conditions. All this affects the quality of cargo transportation.Purpose. The purpose of this article is to systematize various aspects of the commercial operation of a vessel, identify possible commercial risks of sea transportation, as well as factors influencing them.Methods. To solve the problem, the following methods were used: the method of theoretical generalization, the method of analysis and synthesis, the method of systematization, the method of deduction.Results. It has been determined that the anticipation of commercial risks of sea transportation will allow to develop mechanisms for their timely overcoming and reduce the commercial costs of all interested parties in the carriage of goods by sea. The main reasons for thegeneral accident of the container ship Ever Given in the Suez Canal are considered and analyzed and the consequences that it caused for the stakeholders of transportation and international maritime shipping in general are identified.Originality. Potential commercial risks of sea transportation have been identified using the example of the accident with the container ship «Ever Given». It is proposed to develop alternative options for a prompt solution to such problems in the future.Output. The blockage of the Suez Canal by the container ship Ever Given will have long-term repercussions, but such incidents could be deliberately provoked, affecting global and local trade in a targeted manner. There is a need to improve the safety of navigation by optimizing pilotage, especially during sandstorms and other situations where visibility is difficult.Keywords: commercial operation of a vessel, risks, sea transport, seaport, navigation safety