Two Russian icebreakers have become stuck in metre thick ice fields, on their return from a journey to escort supplies to Russia’s northernmost port.
More counterexamples. From the Siberian Times:
Icebreakers make historic Arctic voyage, then get stuck in frozen sea on return journey
By The Siberian Times reporter 17 January 2017
Vessels could be marooned ‘for a week’ in East Siberian Sea after getting caught in thick ice.
Bulk carriers Sinegorsk and Johann Mahmastal made a successful midwinter cargo crossing from Arkhangelsk to Russia’s northernmost port of Pevek, Chukotka, escorted by icebreakers Kapitan Dranitsyn and Admiral Makarov.
It was the first such crossing since Soviet times, and the ships delivered supplies for the supplies for the world’s first floating heat and power plant to be assembled in Chukotka after a journey lasting from 14 December to 7 January.
The ease of the sailing is seen as a sign that climate warming in the Arctic can open up shopping lanes even in midwinter. But the climate remains unpredictable as the four vessels have discovered on their return route.
They are currently trapped by sudden thick ice around Chukotka’s northernmost cape Shelagsky, some 24 nautical miles from Pevek, in some of Russia’s most exposed waters.
Ruslan Nazarov, chief of Chukotka’s emergencies service, said: ‘The ice around Cape Shelagsky is at 10 points. The ice fields are more than one metre thick. The ice compression is strong and hummocks are higher than 2.5 metres.