Optimal Sailing Research Articles

Impact analysis of the traffic convoy system and toll pricing policy of the Suez Canal on the operations of a liner containership over a long-haul voyage

This paper takes an initiative to quantitatively assess the impact of the traffic control scheme and the stepwise toll pricing policy of the Suez Canal on the optimal sailing schedule of a liner containership. We develop a mixed-integer nonlinear programming model for the optimal sailing schedule of a containership over a long-haul voyage via Suez. A case study on a 13000-TEU containership running on the LP4 service of APL shows several managerial insights: a) ignoring the traffic control system at Suez in ship speed optimisation may lead to an infeasible sailing schedule, and underestimate the operating cost (even the bunker cost) of a containership on a long-haul voyage via Suez; b) the optimal ship recovery plan in terms of its sailing speeds is mainly determined by the predefined port time windows, delay situation and Suez-clock time, but not pretty much affected by the levels of bunker price and transit due.

Impact analysis of the traffic convoy system and toll pricing policy of the Suez Canal on the operations of a liner containership over a long-haul voyage

This paper takes an initiative to quantitatively assess the impact of the traffic control scheme and the stepwise toll pricing policy of the Suez Canal on the optimal sailing schedule of a liner containership. We develop a mixed-integer nonlinear programming model for the optimal sailing schedule of a containership over a long-haul voyage via Suez. A case study on a 13000-TEU containership running on the LP4 service of APL shows several managerial insights: a) ignoring the traffic control system at Suez in ship speed optimisation may lead to an infeasible sailing schedule, and underestimate the operating cost (even the bunker cost) of a containership on a long-haul voyage via Suez; b) the optimal ship recovery plan in terms of its sailing speeds is mainly determined by the predefined port time windows, delay situation and Suez-clock time, but not pretty much affected by the levels of bunker price and transit due.

Dynamic optimization of ship energy efficiency considering time-varying environmental factors

Nowadays, optimization of ship energy efficiency attracts increasing attention in order to meet the requirement for energy conservation and emission reduction. Ship operation energy efficiency is significantly influenced by environmental factors such as wind speed and direction, water speed and depth. Owing to inherent time-variety and uncertainty associated with these various factors, it is very difficult to determine optimal sailing speeds accurately for different legs of the whole route using traditional static optimization methods, especially when the weather conditions change frequently over the length of a ship route. Therefore, in this paper, a novel dynamic optimization method adopting the model predictive control (MPC) strategy is proposed to optimize ship energy efficiency accounting for these time-varying environmental factors. Firstly, the dynamic optimization model of ship energy efficiency considering time-varying environmental factors and the nonlinear system model of ship energy efficiency are established. On this basis, the control algorithm and controller for the dynamic optimization of ship energy efficiency (DOSEE) are designed. Finally, a case study is carried out to demonstrate the validity of this optimization method. The results indicate that the optimal sailing speeds at different time steps could be determined through the dynamic optimization method. This method can improve ship energy efficiency and reduce CO2 emissions effectively.

A Two-Stage Maritime Supply Chain Optimization Model

Shipping companies usually determine the optimal sailing speed and number of vessels to deploy in their maritime liner services, using a decentralised system, which sometimes extends the transit time between any two ports and thus affects the in-transit inventory and safety stock levels for shippers. On the contrary, if a centralised system is adopted then the shippers' inventory management costs would be considered in the choice of the optimal configuration. This article proposes a model for this trade-off that compares the supply chain optimal solutions and costs of a decentralised versus a centralised system. Assuming that transport demand can either be inelastic or elastic and that end customers' demand to be satisfied by shippers is stochastic, our model provides an optimisation procedure to determine the optimal configuration for any decentralised or centralised liner service, along with a specific application to a containerised Europe-Far East service.

Search for optimal sailing policy

A dynamic programming model has been formulated to derive the minimal time sailing route for a vessel to sail from an origin to a destination, while passing n different segments in which deterministic wind conditions prevail. Turning times and crossing wind-lines were considered. A discrete computer solution procedure was programmed that had to cope with ranges of inadmissibility of the continuous decision variables caused by inability to sail at certain angles around a facing wind. Binary search method and iterative refinement schemes were applied to reduce calculation times to the order of magnitude of one minute, while obtaining sufficient accuracy. Numerical examples are provided. Sensitivity analysis has indicated robust behavior of the best derived solutions with respect to changes in the values of the different parameters. Despite of numerical validation the best derived solution is not termed optimal, as optimality was not been proven mathematically.

Real-time optimization of ship energy efficiency based on the prediction technology of working condition

Ship energy efficiency management and control is an effective strategy to improve the marine economy and reduce CO2 emission. The determination of the best navigation speed under different working conditions is the basis and premise for real-time improvement of ship energy efficiency. In this paper, the working condition in short distance ahead of the ship related to navigation environment factors was predicted by the method of wavelet neural network, and then the best engine speed for the optimal energy efficiency under different working conditions could be determined through the established ship energy efficiency real-time optimization model. Further, by presetting the ship engine at this optimal speed, the ship energy efficiency could be guaranteed at the optimal state when the ship arrived at the navigation environment ahead of the ship, thus achieving real-time optimization of ship energy efficiency under different navigation environment factors. Experimental studies showed that the proposed optimization model was effective in energy saving and emission reduction, which could provide theoretical guidance for optimal sailing of the ship in service. Compared to traditional setting speed navigation methods, our proposed method has more practical significance to the improvement of ship energy efficiency.

Ice retreat in the Russian Arctic seas and assessment of the availability of the Northern Sea Route from satellite passive microwave observations

This paper presents data on the sea ice area decline in the Northern Hemisphere and in the Russian Arctic seas, on the Northern Sea Route in particular, calculated from passive microwave satellite data. Observations show that the Arctic sea ice has reduced by an average of 5% per decade from November 1978 to the present day. It is noted that, since 2007, the highest sea ice area variability has been observed, which increases the uncertainty of the forecast of the ice coverage in the Arctic seas and thus increases risk for ships in ice-covered waters of northern seas. It is demonstrated that the decrease in summer sea ice area, observed at the end of the melt season, is much more intense than the total decrease in the Arctic sea ice area. On average it is 13% for September for the Arctic as a whole and from 24 to 40% per decade for the seas of the Russian Arctic. The study of changes in the ice conditions in the Northern Sea Route has been carried out for one of the optimal sailing routes. The results indicate a decrease in the ice concentration on the route in the summer months and almost complete route opening in September for the period from 2008 and 2012. It is shown that data from microwave radiometers can be used in the study of ice conditions in the Kara Gates and Vilkitsky Strait. The ice concentration reduction in both water channels is indicated. In the Kara Gates it is 15% and in the Vilkitsky Strait it is 9.5% per decade.

Fundamental properties and pseudo-polynomial-time algorithm for network containership sailing speed optimization

In container liner shipping, bunker cost is an important component of the total operating cost, and bunker consumption increases dramatically when the sailing speed of containerships increases. A higher speed implies higher bunker consumption (higher bunker cost), shorter transit time (lower inventory cost), and larger shipping capacity per ship per year (lower ship cost). Therefore, a container shipping company aims to determine the optimal sailing speed of containerships in a shipping network to minimize the total cost. We derive analytical solutions for sailing speed optimization on a single ship route with a continuous number of ships. The advantage of analytical solutions lies in that it unveils the underlying structure and properties of the problem, from which a number of valuable managerial insights can be obtained. Based on the analytical solution and the properties of the problem, the optimal integer number of ships to deploy on a ship route can be obtained by solving two equations, each in one unknown, using a simple bi-section search method. The properties further enable us to identify an optimality condition for network containership sailing speed optimization. Based on this optimality condition, we propose a pseudo-polynomial-time solution algorithm that can efficiently obtain an epsilon-optimal solution for sailing speed of containerships in a liner shipping network.

Full-shipload tramp ship routing and scheduling with variable speeds

This paper investigates the simultaneous optimization problem of routing and sailing speed in the context of full-shipload tramp shipping. In this problem, a set of cargoes can be transported from their load to discharge ports by a fleet of heterogeneous ships of different speed ranges and load-dependent fuel consumption. The objective is to determine which orders to serve and to find the optimal route for each ship and the optimal sailing speed on each leg of the route so that the total profit is maximized. The problem originated from a real-life challenge faced by a Danish tramp shipping company in the tanker business. To solve the problem, a three-index mixed integer linear programming formulation as well as a set packing formulation is presented. A novel Branch-and-Price algorithm with efficient data preprocessing and heuristic column generation is proposed. The computational results on the test instances generated from real-life data show that the heuristic provides optimal solutions for small test instances and near-optimal solutions for larger test instances in a short running time. The effects of speed optimization and the sensitivity of the solutions to the fuel price change are analyzed. It is shown that speed optimization can improve the total profit by 16% on average and the fuel price has a significant effect on the average sailing speed and total profit.

Neolithic Voyages to Cyprus: Wind Patterns, Routes, and Mechanisms

ABSTRACTRecent archaeological evidence from Cyprus shows that humans first arrived on the island at around 12,000 calibrated years BP. Visits to Cyprus intensified and resulted in settlement of the island during the Pre-Pottery Neolithic A beginning around 11,000 cal BP. Later occupations of the Cypro Pre Pottery Neolithic B from around 10,500 to 9000 cal BP are more numerous and testify to intensive connections with the mainland. Cyprus as an island could have been reached only by seafaring. We examined the possible routes for sailing from the mainland to Cyprus and back to better understand the relationship between the island and the mainland during these periods. The factors that were examined were: sea level; options of available watercraft; sea conditions and currents; navigational skills; sailing routes; and prevailing seasonal and diurnal wind regimes. Because the present wind pattern is understood to generally resemble that of the Terminal Pleistocene pattern, it is suggested that the optimal sailing route and season from the mainland to Cyprus by Neolithic navigators was from southern Turkey between April and October. A passage westward or northwestward from the Levant coast to the southern coast of Cyprus cannot be ruled out. Their return trip was from the east or southeast of Cyprus to the Levant coast. This counter-clockwise Neolithic sailing pattern to Cyprus enabled permanent human settlement of the island and contacts with the mainland.

Multi-Objective Programming Model for Joint Scheduling of Ships in the Complex Water Network

In the complex inland water network, under conditions sufficient to obtain waterway traffic load and ship information, according to the ship and scheduling department's diversity of demand, establish a multi-objective programming model for optimal navigation path selection, the use of linear weighting method to solve the optimal sailing consolidated path, reflecting the characteristics of the river network voyages information and target requirements diversity. Finally, an example preliminarily verified the rationality and validity of the model.

Une fièvre récidivante peut révéler une spondylarthropathie

This paper proposes an ant colony fuzzy neural network (ACFNN) controller for a cruising vessel on a river. The proposed controller comprises an ant colony (AC) algorithm, a fuzzy neural network (FNN) controller, and a switching law. The approximately optimal sailing line and short sailing time are obtained using the AC algorithm. First, the searching pattern of the AC algorithm is constructed using the data of the tidal current, river current, vessel velocity, and position of the coordinate. From a tracking error viewpoint, the switching law determines that the approximately optimal sailing line and the shorter sailing time are obtained using the AC algorithm, and that uncertain nonlinear factors are compensated by the FNN controller. The controller consists of an FNN identifier and a robust controller. The identifier is used to estimate the vessel velocity, and its parameters are tuned online by the adaptive law derived from the Lyapunov function. The robust controller is used to compensate for uncertainties of the tidal current and river current through the estimated law. The output of the ACFNN controller is the sum of the FNN identifier, the robust controller, and an auxiliary function. Finally, a simulation and a practical cruising vessel on a river are performed to verify the effectiveness of the presented controller.

Sailing Path Optimization Analysis with Uncertain Sea Conditions along Upwind-downwind Triangle Course

How to select an optimal sailing route with uncertain sea state information is a key to win. In this paper, firstly the roles of sea environmental parameters for sailboat sailing are analyzed based on hydromechanics principles. And then two-dimension sailing environmental model is set up for upwinddownwind triangle course based on course setting requests. And then the optimal sailing route is planned based on leg division and heading decision fuzzy comprehensive evaluation. Finally, considering the standard of sea conditions required in yachting area, simulations and data analysis indicate the effect of uncertain sea conditions in yachting arena on racing path optimization. The results will guide athletes and instructors to train scientifically.

Optimization of upwind sailing applying a canting rudder device

The research explained in this paper was carried out to investigate the efficiency of different steering systems on sailing yachts. The steering system of a sailing yacht mostly includes a simple steering system and a hydrodynamic shaped single rudder, or multiple rudders, depending on boat characteristics. One of the basic design guidelines for fast sailing yachts involves reducing the wetted surface to the minimum allowed by the dynamic stability while maintaining the optimal sailing performances. Deficiencies of different steering systems are discussed and their influences on total lift and yaw moments; yacht manoeuvrability in different sailing directions is also analysed. The discussion is focused on steering systems applicable in practice and accepted by the yacht-building industry, although several innovations may be found that remained in their development stage because of their complexity in construction, maintenance, use itself and reliability. The canting rudder is analysed applying an uncommon approach for ship building. All measurements have been conducted at sea applying on board sensors for position and acceleration acquirements. The purpose of the research is to demonstrate that the use of the bended rudder can reduce the leeway angle, the upwind sailing angle and increase the velocity made good to windward.

Sailing speed optimization for container ships in a liner shipping network

This paper first calibrates the bunker consumption – sailing speed relation for container ships using historical operating data from a global liner shipping company. It proceeds to investigate the optimal sailing speed of container ships on each leg of each ship route in a liner shipping network while considering transshipment and container routing. This problem is formulated as a mixed-integer nonlinear programming model. In view of the convexity, non-negativity, and univariate properties of the bunker consumption function, an efficient outer-approximation method is proposed to obtain an ε-optimal solution with a predetermined optimality tolerance level ε. The proposed model and algorithm is applied to a real case study for a global liner shipping company.

Neumayer, Humboldt and the search for a global physics

In setting up the Flagstaff Observatory in Melbourne in 1857, the young German geophysicist Georg Neumayer brought new standards of precision to the pursuit of physics in Australia. His wide-ranging research program in geomagnetism, meteorology and oceanography was conceived within an overall approach to science associated especially with the name of Alexander von Humboldt, that saw the Earth and its oceans and atmosphere as an integrated dynamical system. Neumayer also, however, envisaged immediate practical outcomes from his work, whether in determining optimal sailing routes between Europe and Australia, or in locating new mineral deposits. From a personal point of view he regarded his seven years in Australia as, above all, a preparation for the scientific investigation of Antarctica that he dreamed in vain of undertaking.

Winter navigation in the Northern Sea Route using RADARSAT data

AbstractThe results are presented of the first winter ice navigation demonstration, using synthetic aperture radar (SAR) images from the Canadian satellite RADARSAT, onboard the nuclear icebreaker Sovetskiy Soyuz in the Kara Sea region in April–May 1998. While ERS SAR data only could cover part of the sea ice in this large area, the demonstration showed that RADARSAT ScanSAR images with 100 m pixel size could be used to map all relevant ice areas with a few 500 × 500 km scenes. SAR images transferred onboard icebreakers in near real time offer an excellent possibility to select optimal sailing routes in difficult ice conditions such as those that were encountered by this expedition. SAR images were also used for planning of operations prior to the expedition. This study compares sub-satellite sea-ice observations with RADARSAT SAR as well as Okean side-looking radar (SLR) signatures of the major ice types and features found in the Kara Sea during winter. Wide-swath SAR images will become available from several new satellites in the near future, such as Envisat, scheduled in 2001, and RADARSAT-2, in 2002. Satellite SAR images will therefore play an increasingly important role in operational ice monitoring both in the Northern Sea Route and in other ice areas.