Frozen ocean, big boats, powerful engines and deliberate, full-speed collisions, icebreakers are ships we tend not to think much about, but they’re worth a longer look. They don’t work how you think they might.
NASA’s just published a new update on the activities of arctic coastguard vessel Healy–a science ship with 5,000 square feet of laboratory and support space that charges through the remote waters of the Arctic Ocean. The ship carries a large crew of scientists and specialists to investigate subjects as diverse as levels of oxygen to uptake of atmospheric CO2 for global warming research. But to perform its science missions, Healy has to push its huge mass through heavy ice.
Check out this report from June 26, when Healy was situated in an ice floe at 72° 06’ 2” N, 160° 41’ 8” W, which explains what’s going on when it barges through ice:
Since the floe is so large, there is really nowhere for the ice to go except in our track-line behind us. In pressure ridge and rubble areas, we back and “ram” into the ice, and may only move 30 or 40 yards with each back and “ram.” The “ram” part of this is not how it sounds. The Healy’s bow is sloped such that we ride up on the ice with the help of momentum, and then our 16,000 ton weight crushes the ice downward and along the sides of the ship. The power we use would propel the ship to at least 16 knots in open water, but in the ice our speed rarely exceeds 6 or 7 knots. The rest of this energy goes into the ship riding up on the ice and crushing it downward
The problem is that ice, while pretty fragile in tension is actually surprisingly strong in compression. This means a ship cannot ram head-on through feet-thick ice. But forcing the heavy ship up on top of the ice layer, and relying on its weight to fracture the ice across its thinnest direction, is effective. The smashed ice then gets thrust aside by the boat, and floats its way into the broken-ice trail in the ship’s wake.
To see an example of a truly huge icebreaker in action barging its way through the Arctic, check out the clip below: It’s a vessel that dwarf’s NASA’s–the 50 Let Pobedy. It’s the most powerful icebreaker ship in the world, nuclear powered, and sure to turn the biggest floe into tidy chunks.
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