Cap­tain Hamil­ton’s Im­pec­ca­ble In­stinct for the Ice

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On deck with the cap­tain of a U.S. Coast Guard ice­breaker

Trenches tear open, pow­er­ful plates slide over each other, and mile-high ram­parts sud­denly freeze into place: No air­plane is able to land here, and he­li­copters nor­mally have a range of only a few hun­dred miles.

HOW MUCH ICE DOES AN ICE­BREAKER BREAK?

Most ice­break­ers make the frozen wa­ter­ways pass­able for other ships. Par­tic­u­larly sta­ble and strong types such as the Healy can nav­i­gate the Arc­tic and the Antarc­tic, mainly for pur­poses of re­search or sup­ply­ing po­lar sta­tions. But how do you find your way across a land­scape that’s con­stantly be­ing re- cre­ated in slow mo­tion, and some of the ob­sta­cles pro­duced in the process are as hard as steel? “The ice leads us across the sea, we must fol­low its course,” says Hamil­ton. As the ship moves ten­ta­tively through the ice, Hamil­ton can es­ti­mate the thick­ness of the bro­ken floes by us­ing an ice level at the bow of the ship. Two sen­tinels 100 feet up help him: One looks for ob­sta­cles in front of the bow and the other keeps an eye on the hori­zon. “Gaps in the ice can be rec­og­nized by gray haze hang­ing over the sea: Mois­ture rises up from the gap and con­denses in the air. On the other hand, ice blinks, which are lu­mi­nous streaks in the sky near the hori­zon, in­di­cate where ice floes are be­cause ice re­flects light bet­ter than wa­ter,” says Hamil­ton.

But what if there are thick ice floes ev­ery­where block­ing the way? How do you find the hid­den path of least re­sis­tance? “If the ice is up to 5 feet thick, we’ll go through in a straight line. If it is any thicker than that we have to nav­i­gate along cracks and crevices in the ice, even if that can some­times mean a 90-de­gree turn, and, in ex­cep­tional cir­cum­stances, it can even lead up to a dead end,” Hamil­ton ex­plains.

But the de­ci­sive fac­tor isn’t just the floes’ thick­ness—it’s the type of ice.

THE ICE LEADS US ACROSS THE SEA, WE MUST FOL­LOW ITS COURSE

“Fresh bright white ice is eas­ier to break than old ice that shim­mers blue,” says Hamil­ton. “In ad­di­tion, fresh wa­ter from rivers and glacial slopes freezes much harder than sea­wa­ter. Ice made of fresh wa­ter is por­ous and, es­pe­cially af­ter it has just been formed, al­most rub­bery.” That’s be­cause sea­wa­ter con­tains crys­tals of salt, which dis­solve and ul­ti­mately make the ice brit­tle. And though there is no land at the North Pole, fresh­wa­ter ice is found there much more fre­quently than it is in the wa­ters sur­round­ing Antarc­tica. Rea­son: The huge rivers of Siberia carry a lot of ice to the Arc­tic Ocean.

CAN ICE ACT LIKE AN EX­PLO­SION?

Whereas in the con­tainer ship­ping in­dus­try speed and timeta­bles are of para­mount im­por­tance, for those col­leagues who nav­i­gate the poles, ar­riv­ing at all means the voy­age was suc­cess­ful. Even the most pow­er­ful nu­clear- pow­ered ice­break­ers can get stuck in the pack ice. This ex­erts an in­cred­i­ble amount of pres­sure, as Cap­tain Uwe Pahl of the ice­breaker RV Po­larstern had ex­pe­ri­enced off the coast of Spits­ber­gen in Nor­way: “The tides, cur­rents, and wind move floes that squeeze a ship up­ward by 3 feet like a cork—a ship that weighs 17,000 tons.” The pres­sure ex­erted upon the hull can be greater than in the bar­rel of a gun or on the deep­est sea floor. So it stays in­tact, the hull’s outer skin is forged from 2 inches of spe­cial steel, mak­ing it three times as thick as a con­ven­tional ship’s hull. Even that is no guar­an­tee of safety: “Pa­tience is our high­est virtue,” says Hamil­ton. Most ac­ci­dents in the ice hap­pen be­cause of inat­ten­tion and ex­ces­sive speed, es­pe­cially at night when only the ice radar and two or three strong head­lights show the way for­ward. “A high-speed col­li­sion with an ice­berg can put lives at risk. Then we re­ally have a prob­lem…”

ICE FLOES PROPPED OUR 17,000-TON SHIP UP BY 3 FEET

JOUR­NEY THROUGH A WALL OF ICE Cap­tain Ja­son R. Hamil­ton com­mands the 85 crew mem­bers of the U.S. Coast Guard’s Healy ice­breaker. There are also around 50 sci­en­tists on board dur­ing this trip— at the time this ar­ti­cle went to press, Healy was mak­ing its w

HE­LI­COPTER Po­lar mis­sions usu­ally in­clude one or two he­li­copters: Among other things they scout the ice con­di­tions ahead so the cap­tain can de­ter­mine the op­ti­mal route. FUEL To achieve full per­for­mance, ice­break­ers usu­ally use three or even four en­gines

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