The fifth in a series of dispatches from freelance writer Brandon Reynolds aboard the USCG icebreaker Polar Star, on its annual resupply mission to the research base, McMurdo Station. It’s a critical task imperiled by the nation’s aging, shrinking fleet of ice-breaking ships.

The plan was this: groom the channel; spend a few days at McMurdo Station; escort a supply ship and a fuel tanker in; go north to Marble Point to refuel a National Science Foundation depot; wander across the arc of the continent and then dart north across the chaotic Southern Ocean and up the coast of South America to Valparaiso and points north.

But if there’s one thing I’ve learned on this ship, it’s that plans are suggestions and suggestions are dreams and dreams here are more familiar than reality. Things change at a moment’s notice. Mostly by breaking.

There are arcane equations that affect the ship, dealing with power output, weight distribution, atmospheric behavior, celestial navigation, on and on. There is only one that really means anything to the average dim-but-curious writer, and that’s the relationship between cutting a channel through the ice and the damage it causes; in other words, the ratio of breaking-in to breaking down.

The ice is, in scientific terms, absolute hell on the ship. Polar Star breaks in a variety of ways, and that delays the grooming of the channel, the only way that supply ships can get in. So when we’re back underway we speed along to the next breakdown. Are these critical breakdowns? They’re serious enough. Most of them are, strictly speaking, mission-enders — for a few hours. Then we’re on our way again.

What’s happening here that keeps the engineering department busy with repairs is a living example of the paradox of the implacable force against the immovable object. Polar Star is the last working heavy icebreaker in the U.S. fleet, and with 75,000 horsepower, it’s billed as the “most powerful non-nuclear icebreaker in the world.” The bow is nearly two inches thick, made of a special steel alloy that’s resistant to the cold and — more than 40 years after the keel was laid — no longer made in the United States. For durability, the frames (the ship’s “ribs”) are about six inches closer together than normal. The football-shaped bow allows the ship to slide (or grind, as it were) up onto the ice like an aggressive leopard seal and break through it. That takes a lot of power.

Most of the time, Polar Star runs on six Alco 251 diesel-electric generators. These are train locomotive engines, but they’re also used for icebreakers and nuclear power plant backups. They even make a satisfying chugga-chug chugga-chug, which is quite soothing when we’re out at sea. (During what qualifies as night during the austral summer, I lie in my “rack” and listen to the sound of distant trains along with the foamy hiss of the waves against the bow, a real surf ’n’ turf for the senses.)

These six engines generate power which is fed to three motors which turn the three shafts attached to the three propellers that make us go. Then, when it’s time to break ice, they fire up the jet engines.

In addition to the diesel-electrics, Polar Star also carries three Pratt & Whitney FT4 gas turbines, the kind once used in Boeing 707s. Each turbine is in its own chamber, and when they get turned on and you stand next to them, even with earplugs, it’s the kind of sound and force that you have to keep yourself from instinctively running away from, a terrible thrill like I imagine swimming with sharks would be. The turbines are each cranked down to a manageable RPM by a reduction gear and connected to a shaft, and when they’re all three going strong, they produce up to 75,000 hp. Power at that level is hard to imagine. I’ve seen what it can do, though. Plow through miles and miles of ice as thick as I am tall, tossing up fragments the size of Volkswagens into a channel cut to the horizon.

It’s well-designed, this ship. But still, stuff breaks all the time. Sometimes the turbines won’t start up, sometimes the diesels crap out, sometimes—a lot of times, lately—the vibrations through the ship from the bow smashing the ice and the propellers “milling” the ice, breaks anything connected to the shaft. Even for a ship built for this, it is an enormous amount of stress. There’s plenty of power. But there’s always more ice.

A few days ago, a crack was found in the reduction gear, a part of the ship’s propulsion system. It seemed like just another in a series of breakdowns, but this was one that gave Capt. Matt Walker cause to abandon the Marble Point mission. The ice would be thicker there, he said, and he didn’t believe the ship was up to the task of breaking through. “I made a decision to forego Marble Point because Marble Point is a nice mission but it’s not an essential mission,” he said. She’d done it two years before, so I took this as evidence of age wearing Polar Star down.

The crew I’ve talked to is of two minds about breakage. One attitude is that breakage is inevitable, that it’s the natural order of things around here, so they fix the damage and get on with it. They’re an industrious bunch. Fixes have included welding and replacing, but also, in a couple of cases, Super Glue and a surfboard repair kit.

The other perspective sees the law of diminishing returns at work. As Polar Star (now in her 40s) gets older, she breaks more — both more often and more seriously. More breakage not only imperils or at least alters the mission, as it did with Marble Point, but it also means more time in dry-dock, where repairs have to be hurriedly accomplished so that she can head out again for the next trip south.

Between Deep Freeze and dry-dock in Vallejo, Polar Star was out of home port something like 320 days. The day may well be at hand when Polar Star will only oscillate between going south and being fixed after going south.

Next Time: The End of the World!

Brandon R. Reynolds lives in Los Angeles but currently summers in the Antarctic Circle. He has written for San Francisco Magazine, SF Weekly, The Atlantic, and Oxford American (not the dictionary).