Modification of ship routing algorithms for the case of navigation in ice (original) (raw)

A system for route optimization in ice-covered waters

Cold Regions Science and Technology, 2009

Information about ice is indispensable to navigation in ice-covered sea areas. For vessels traveling long distances in ice, it is worth planning routes that will reduce fuel consumption and travel time, as well as the risk of ending up in hazardous areas or getting stuck in the ice. In addition to observations on board, there is a multitude of data sources available for seafarers like satellite images, ice model data, weather observations and forecasts. However, it is difficult for a human to take into consideration all the time-varying data parameters when planning a route. In this paper, a prototype system for optimizing routes through the ice field is presented. The system integrates state-of-the-art ice modeling, ship transit modeling, and an enduser system as a route optimization tool for vessels navigating in ice-covered waters. The system has recently been validated on board merchant vessels in the Baltic Sea, and the system's performance has been analyzed statistically using AIS data. Based on the AIS data analysis the mean relative error of the estimated transit time was 0.144 [s/s] with a standard deviation of 0.147 [s/s] for long routes (90-650 km), and 0.018 [s/s] with standard deviation of 0.193 [s/s] for 50 km route segments.

A method for ice-aware maritime route optimization

2014 IEEE/ION Position, Location and Navigation Symposium - PLANS 2014, 2014

We present a method for ice-aware maritime route optimization. Our aim is to increase the safety and efficiency of maritime transport under icy conditions. The proposed method is based on the A* algorithm, developed by Hart et al. It uses a model of maritime navigation, consisting of (1) a sea spatial model, (2) ship maneuverability model, (3) sea ice model, and (4) ship performance model. The sea ice model, which provides a snapshot of the sea ice conditions, is based on previous work by the Finnish Meteorological Institute. The ship performance model, based on previous work by Kotovirta et al., estimates ship transit speed as a function of ice conditions and ship design parameters.

Graph-Search and Differential Equations for Time-Optimal Vessel Route Planning in Dynamic Ocean Waves

IEEE Transactions on Intelligent Transportation Systems

Time-optimal paths are evaluated by VISIR ("dis-coVerIng Safe and effIcient Routes"), a graph-search ship routing model, with respect to the solution of the fundamental differential equations governing optimal paths in a dynamic wind-wave environment. The evaluation exercise makes use of identical setups: topological constraints, dynamic wave environmental conditions, and vessel-ocean parametrizations, while advection by external currents is not considered. The emphasis is on predicting the time-optimal ship headings and Speeds Through Water constrained by dynamic ocean wave fields. VISIR upgrades regarding angular resolution, time-interpolation, and static navigational safety constraints are introduced. The deviations of the graph-search results relative to the solution of the exact differential equations in both the path duration and length are assessed. They are found to be of the order of the discretization errors, with VISIR's solution converging to that of the differential equation for sufficient resolution.

Evaluation Criteria and Approach to Voyage Planning in Ice. Verification on the Example of German Ship Activity During the Second World War

Annual of Navigation, 2018

Vessels designed for navigation in ice can perform voyage with the assistance of icebreaker in the navigation season in case an ice cover area is less than 20%. Whereas the same vessels could carry out successfully completed voyage through the NSR with intensive icebreaker help at the ice-covered area lower than 42%. Navigation of the same vessel at ice covered area above 80% is possible with intensive icebreaker help, but it threatens to damage the hull, rudder or propeller. Excessive generalization of data analyzed may cause to wrong, even opposite conclusions. Using only basic statistical information in the form of average values and standard deviation may be not sufficient for the purpose of vessel’s voyage planning in areas covered with ice. Much more opportunities for the assessment of navigation in ice covered regions provides cumulative distribution, which should be related to the time and geographical space distribution. It allows to determine the duration of time window fo...

Minimum Time Sailing Boat Path Algorithm

IEEE Journal of Oceanic Engineering

An iterative procedure to solve the nonlinear problem of fastest-path sailing vessel routing in an environment with variable winds and currents is proposed. In the routing of a sailing vessel, the primary control variable is the pointing (heading) of the vessel (assuming that the sails are chosen and trimmed optimally). Sailing vessel routing is highly nonlinear when considering environmental factors, such as winds and currents, and the behavior of the boat, given the weather conditions (i.e., polar diagrams that predict how fast one can sail, given the vessel's pointing relative to the true wind and the wind speed). The key algorithmic contribution of this article is a fastest-path algorithm for graphs with nonconvex edge costs that depend on weather, current, and boat polars. An illustrative scenario, with idealized weather attributes, and a real-world scenario, with parameters generated by numerical weather and current prediction models, are simulated and tested to compare the proposed algorithm against open-source routing software validated by active sailors. Preliminary results from the simulation setups tested are as follows: 1) the proposed sailing boat path algorithm is comparable to the open-source software available; and 2) exploiting the often unused but significant impactor of surface currents and incorporating leeway into sailing boat path planning enables higher fidelity guidance and faster (i.e., shorter time) routes, in comparing against the freely available baseline.

Common solutions and challenges to the traverse of sea ice by ships

2015

The specific challenges of ship operations in sea ice-covered waters of the Arctic depend on factors including the purpose of the operation, the capabilities of the ship and equipment available, the degree of situational awareness and crew experience. Focusing on transits of sea ice in the waters of the Northern Sea Route (NSR), this study demonstrates that the solutions currently employed range from active route finding to accepting getting beset in ice, apparently depending on the purpose of operation. Challenges and operational constraints are discussed. The analysis is based on data provided by the NSR Administration, vessel motion data from satellite-borne receivers of Automatic Identification System signals (S-AIS data of AISSat-1), and sea ice products (AMSR2 ice concentration, ice charts). Travel times northeast of Severnaya Zemlya ranged from 1 to 6 days, depending on ice pressure. A statistical relationship between travel time and ice conditions has been obtained east of t...

Towards an Automatic Ice Navigation Support System in the Arctic Sea

ISPRS International Journal of Geo-Information, 2016

Conventional ice navigation in the sea is manually operated by well-trained navigators, whose experiences are heavily relied upon to guarantee the ship's safety. Despite the increasingly available ice data and information, little has been done to develop an automatic ice navigation support system to better guide ships in the sea. In this study, using the vector-formatted ice data and navigation codes in northern regions, we calculate ice numeral and divide sea area into two parts: continuous navigable area and the counterpart numerous separate unnavigable area. We generate Voronoi Diagrams for the obstacle areas and build a road network-like graph for connections in the sea. Based on such a network, we design and develop a geographic information system (GIS) package to automatically compute the safest-and-shortest routes for different types of ships between origin and destination (OD) pairs. A visibility tool, Isovist, is also implemented to help automatically identify safe navigable areas in emergency situations. The developed GIS package is shared online as an open source project called NavSpace, available for validation and extension, e.g., indoor navigation service. This work would promote the development of ice navigation support system and potentially enhance the safety of ice navigation in the Arctic sea.

Multi-Objective Weather Routing of Sailboats Considering Wave Resistance

Polish Maritime Research, 2018

The article presents a method to determine the route of a sailing vessel with the aid of deterministic algorithms. The method assumes that the area in which the route is to be determined is limited and the basic input data comprise the wind vector and the speed characteristic of the vessel. Compared to previous works of the authors, the present article additionally takes into account the effect of sea waves with the resultant resistance increase on the vessel speed. This approach brings the proposed model closer to real behaviour of a sailing vessel. The result returned by the method is the sailing route, optimised based on the multi-criteria objective function. Along with the time criterion, this function also takes into account comfort of voyage and the number of performed turns. The developed method has been implemented as simulation application SaillingAssistance and experimentally verified.

Making a Channel in Ice for Large-Size Ships Using a Curvilinear Icebreaker Path and Other Methods Overview

2013

Traditionally, the commercial vessels are sailing in ice through a channel made by an icebreaker. This tactics proved to be quite good for ships with hulls of lesser beam than that of the icebreaker they follow. Today there is an ever increasing demand for large-size carriers much wider than icebreakers. In this connection more efficient methods to assist these vessels through ice have to be developed. The paper suggests a different tactical method when the icebreaker leading a large-size vessel is following a curvilinear path with a certain turning radius. This method makes it possible to reduce ice loads on the large-size vessel. This effect is achieved because the vessel partly drives through ice cake while passing directly through the channel made by the icebreaker, and also alternatingly one of the vessel hull sides breaks off small floes into the channel behind the icebreaker while the other hull side of the same vessel breaks the ice by bending. The paper contains estimations of the icebreaker path, analysis and estimations of the vessel's ice resistance and speed in all phases of sailing through the water infested with small floes. The ice conditions suitable for this tactics are determined; the maximum safe speeds of the icebreaker and vessel are estimated to ensure fail-free operation. The paper also reviews other existing icebreaker-assisted operation tactics for the cases when one ice-breaker leads a large-size vessel in continuous level ice fields. These tactics are analyzed to compare and appreciate the advantages of the curvilinear-path tactics.