Tom Waters saves all year to indulge in his only hobby: guessing when ice will melt.

　　For US$2.50 a pop, he and thousands of others try for a piece of a US$300,000 jackpot by predicting the exact minute when spring will loosen the frozen cover of the Tanana River at Nenana enough to move it downstream.

　　Kentucky has its Derby, Indianapolis its 500. Alaska's rite of spring is the Nenana Ice Classic.

　　Residents of Nenana, a city of 500 about 90 kilometers south of Fairbanks, have gambled on when the ice will leave the Tanana for 87 years. "Breakup" on the Tanana and Yukon rivers in the early 1900s meant the waterways could again be used by sternwheelers to haul people and cargo 800 miles west from the Bering Sea.

　　In 1917, surveyors for the Alaska Engineering Commission, the federal agency charged with building the Alaska Railroad, were waiting for open water so boats could bring up material they needed to go to work. They passed the time by anteing up about US$800 to form an ice-betting pool.

　　The kitty grew and over the years has paid out nearly US$10 million in prize money.

　　To detect movement in the ice these days, Ice Classic organizers erect an 8.4-meter wooden tripod about 60 meters from shore just upriver from the 390-meter highway bridge. They hook a cable from the tripod to the official Ice Classic clock. When the tripod moves 30 meters, the wire trips the clock.

　　Former Lieutenant Governor Jack Coghill, 78, was born and raised in Nenana and presided as mayor for 22 years. Coghill was one of 10 people to hold a winning ticket in 1952, when the pot was US$180,000. He used his US$18,000 to buy a sawmill, cut lumber and build a hotel, since converted to a combination courthouse, coin-operated laundry, beauty parlor and two-unit apartment house, where he now lives.

　　The Ice Classic is not just a rite of spring, Coghill said, but a commemoration of Alaska transportation before roads, airplanes and trains.

　　Given the variables, there's no way the contest could be rigged, he said.

　　The king of the guessers since 1978 has been Waters, 46, of Fairbanks. Most people buy a ticket or 10. Waters this year purchased 2,250 at a cost of US$5,625 by scientifically tracking past breakups.

　　The first year he entered, his best guess was an hour off - his all-time worst finish.

　　Since then he picked the correct minutes twice and won US$10,000 in 1979 and US$14,700 in 1983. Waters missed the jackpot by two minutes last year.

　　Some people are less methodical. The Ice Classic last year received 66 guesses for April 31, a date that doesn't exist.

　　(The Associated Press)