Chicago Fire Department's icebreaking boat makes its way down Chicago River

CHICAGO - With a big winter storm headed our way, and temperatures set to plunge once again, one of Chicago’s favorite winter traditions is well underway.

The Chicago Fire Department’s icebreaking boat made its way down the Chicago River Tuesday afternoon, tearing through thick sheets of ice.

It’s one of the most spectacular sights Chicago has to offer. 

But the first thing you notice is the noise.

Grinding, crushing and occasionally popping, sheets of ice fracture into little jigsaw puzzle pieces under the massive weight of the Christopher Wheatley.

"It’s designed as an icebreaker. It can cut up to almost 15 inches of ice going through it," said Jason Lach, Deputy District Chief of the fire department’s Marine and Dive unit.

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Lach said hammering through the ice is critical for two reasons; creating pools of open water for dive rescue teams should somebody fall into the river, and preventing sheets of ice from tearing up the Riverwalk.

"10, 12 inches of ice does a lot of damage to the piers, the concrete and all that stuff," said Lach. "So we try to break it up. This protects the Riverwalk and everything going on here."

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If you look at the front of the boat, you’ll see it doesn’t actually cut through the ice.

Instead, it crushes it, with a hull made of tons of concrete and reinforced steel. 

"It will virtually climb on top, and settle down and break as you go," said boat pilot Tom Courtney.

Mother Nature makes the call on how long they’ll be icebreaking the river, some years hardly at all and other years up to St. Patrick’s Day.

But after making scores of winter water rescues and pulling bodies out from under the ice, Lach says there’s something you need to know. 

"Remember there’s no such thing as safe ice," said Lach. "Anytime you venture out onto it, you can’t see any of the voids, the slick areas or the holes in there. There is no such thing as safe ice. Avoid walking on it at all costs."