Modification of Canadian Ice Regime System to Include Ship Operation

(By Robert Frederking ; INSROP Working Paper No. 161 – 1999, I.2.5)

Data on ice navigation experience in the Russian Arctic was obtained for Russian Registry ULA, UL and L1 vessels. The data comprise transit times and distances for voyage segments and a description of ice conditions according to WMO terminology for each voyage segment. This is a useful data set for analysis of navigation experience and testing of methodologies for predicting safety and effectiveness of navigation in ice covered waters.

The Canadian Arctic Ice Regime Shipping System (AIRSS) uses ice conditions and vessel class to provide guidance on safe navigation in ice. The severity of ice conditions is quantified by a WMO-based ice regime in relation to multipliers based on ship type to calculate an Ice Numeral. In the AIRSS this Ice Numeral is used to define conditions for safe vessel operation in ice. If the Ice Numeral is positive or zero, navigation is safe, but if it is negative, navigation is unsafe. No allowance is made for operational factors such as speed or visibility. Ice Numerals have been determinated for a number of vessels operating in the Russian Arctic and in turn related to average vessel speed and damage. The actual number and degree of damage is small, however, a negative Ice Numeral is an indicator of a higher risk of damage.

The AIRSS has been modified to take into account ice decay, ridging, floes size and icebreaker escort to calculate a Transit Numeral. The Transit Numeral is an indicator of ice severity; zero represents very severe conditions for a vessel while 50 represents conditions equivalent to open water. Transit Numeral has been related to average transit speed in ice. In the case of ULA and L1 vessels, there is a general trend of increasing average transit speed with increasing Transit Numeral. For Transit Numerals greater than about 35 average transit speed is independent of ice conditions. The ice navigation data have been analysed to predict mean speed. These transit speeds provide an experience-based indication of expected long-term ship performance in actual practice along the Northern Sea Route.

Robert Frederking, 1999, Modification of Canadian Ice Regime System to Include Ship Operation, INSROP.©