Analysis of ice conditions of year-round navigation of Arc7 vessels in the southwestern part of the Kara Sea

Abstract

Since 2006, a new generation of reinforced ice class Arc7 vessels has been operating on the Northern Sea Route. Safe and efficient sailing of this type of vessels in sea ice demands a detailed study of ice conditions. Accumulation and analysis of data on ice and hydrometeorological conditions for the entire Arctic in comparison with ice conditions along the route of vessels is an essential part of the development of optimal variants and optimal routes for ice navigation.The main aim of the study was to generalize the conditions of ice navigation of Norilskiy Nickel vessels along the optimal navigational routes in the south-western part of the Kara Sea. Based on the reports on sailing obtained from vessels of the “Norilskiy Nickel” type for the 2006–2014 period, we calculated the probability of choosing the optimal route along the Murmansk – Dudinka passage: through the Kara Gate Strait (seaward, central or coastal route) or the north of Cape Zhelaniya. During the year, vessels move predominantly through the Kara Gate. However, for three month per year, from April to June, the most appropriate route lies to the north of the Zhelaniya Cape. In April – May it is, on average, every second navigation, and in June – more than 80 % of all navigation. The features of the ice regime determining the choice of the specific navigation route, are described. The speeds of vessels of the “Norilskiy Nickel” type along various navigation routes in drifting sea ice of the Kara Sea are calculated. The fastest speed in drifting ice was recorded in the winter navigations of 2007–2008 and 2011–2012, in the January-May of these years the average speed was 10.2 and 11.2, correspondingly. The minimum speed in these years, even during the months of maximum ice cover growth, was not less than 4.8 knots. In other years, the average speeds were in the range of 9.2–9.8 knots. During the whole period of study, ice conditions that were extremely difficult for navigation formed three times: at the end of May 2009, at the end of March 2010 and in the middle of March 2011, these are considered in more detail in the present article.