“....The Polar Star is just returning to service after a years-long, $90 million overhaul. It’s designed to get through a 6-foot-thick (2-meter-thick) layer of ice when it’s sailing at 3.5 mph — and when it’s in its backing-up-and-ramming mode, it’s capable of handling ice that’s up to 21 feet (6.5 meters) thick....”
http://www.nbcnews.com/science/how-icebreakers-work-sometimes-dont-work-2D11821223
What is missing in the advertising of the specs for the USCGC POLAR STAR is that it is a maintenance hardship. She is in dry dock and year-long maintenance stints more than she is underway lately. We’ll see how she holds up.
Those stats of “handling” 6.5 meters of ice means that it takes a running start, runs atop the ice, the weight of the ship cracks it down, then ship applies astern propulsion to set up to take another 50 meter bite. That takes a very, very long time to go a few kilometers.
I’m with you guys, since 1971 and again tomorrow.