Preliminary study on the applicability of the POLARIS methodology for ships operating in lake ice

• Main Authors: Tremblett, Adam J., Garvin, Matthew J. B., Taylor, Rocky, Oldford, Dan
• Format: Article in Journal/Newspaper
• Language: English
• Published: Lulea University of Technology 2021
• Subjects: ice; ice-class; POLARIS; shipping; lakes; sea ice; stars; Arctic; Icebreaker; Sea ice
• Online Access: https://nrc-publications.canada.ca/eng/view/object/?id=aa1c627f-106c-495b-80c9-8ff07460805e; https://nrc-publications.canada.ca/fra/voir/objet/?id=aa1c627f-106c-495b-80c9-8ff07460805e

A preliminary study was performed to assess the applicability of the Polar Operational Limit Assessment Risk Indexing System (POLARIS) for ships operating in lake ice. POLARIS provides guidance regarding operational limits for ships operating in polar waters, which was developed in association with the IMO Polar Code in 2014. POLARIS uses a Risk Index Outcome (RIO) value based on a ship's ice class and specific ice conditions, which is calculated using a Risk Index that reflects the ship's operational capability in ice. The Risk Index contains a set of Risk Index Values (RIVs) corresponding to different stages of sea ice development for each ice class. AIS records for ships operating in the North American Great Lakes region for ice seasons between 2010 and 2019 were analysed to compare historical vessel operations to the recommendations prescribed by POLARIS, by applying the POLARIS methodology to operations in lake ice instead of its normal application for polar operations. Ice condition information was extracted from the Canadian Ice Service digital charts. RIVs for lake ice types were assigned based on the closest equivalent sea ice types within POLARIS by thickness. Results from this study suggest that Great Lakes shipping operations are generally consistent with POLARIS guidelines and icebreaker support is observed to correspond well with regions where vessels most frequently encounter negative RIO values. While these results indicate that the development of modified POLARIS guidelines for the Great Lakes seem feasible, this work also highlights the need for additional information and further analysis. Areas requiring further investigation include assessing potential for ship damage from lake ice versus sea ice of equivalent thickness, establishing POLARIS Risk Index Values specific to lake ice stages-of-development, and assessing suitable RIVs that reflect operations in freshwater ice. Additional information needed to support this work includes documentation of the ice class of all vessels operating in ...