This time of year working folks on the upper Chesapeake Bay love to see the icebreaker John C. Widener crunching across the frozen horizon.

"That radio will light up once they know we're out here," said the captain, Joe Scharnus, as he rounded Bloody Point Light and headed up Eastern Bay in the Maryland-owned boat. As if on cue, the VHF began crackling with requests for assistance.

His mission last week was to free some clammers stuck behind the ice in the Wye and Miles rivers and at Kent Narrows on the Eastern Shore. But judging by the scenery, the Widener might as well have been at Point Barrow, heading for Nunivak Island off Alaska.

"You said you wanted some pictures," said Scharnus as the Widener inched across a trackless waste, rumbling and roaring. "This is as good a place as any."

So with considerable trepidation the photographer pulled a National Geographic stunt, jumping off the deck onto the nubbly, six-inch-thick ice, then strolling worriedly away from the 72-foot steel boat to snap a few shots.

"Don't worry," said Scharnus, "it's holding us up. It ought to hold you up."

Of course the bay is a beauty in any season, but on a still day in dead winter it has a particular allure.

Just outside their home port of Annapolis, the Widener's crew could see past Poplar Island 10 miles to the south, and beyond the Bay Bridge to the north through the crackling-cold winter air.

"You get back in the creeks and the water is so clear you can see oysters on the bottom 10 or 15 feet down," said crewman John Flatley. "You'll never see that in the summer.

"You can't ask for anything more," added Flatley, scanning a scene few get to enjoy. "Hard water, geese flying and a pretty sky. On days like these we say, 'And they pay us for this.' "

The outfit that pays for the men and the boat to break hard water around the bay is the Maryland Hydrographic Survey, which in summer is responsible for setting buoys defining shellfishing areas and for tending some navigational markers in protected waters.

The Widener and the other state hydrographic survey boats, the H. J. Elser in St. Michaels, Big Lou in Cambridge and the Millard Tawes in Crisfield, would sit all winter -- except that the agency chooses to do what Scharnus called "a little public relations" by helping out stranded folks who make their living on the water.

Happily, four clam boats were ready and waiting at the mouth of the Wye River when the Widener arrived after a two-mile crunch through solid ice. "Sometimes you get there and they just stare at you and go back to the dock and drink coffee," Scharnus said.

"These boys got locked up the river in that cold spell two weeks ago," said Flatley. "They didn't care at the time because there weren't any clams around to catch.

"But now some other watermen found a strike of clams off Kent Island, and they're catching their limit every day. These boys can't stand to sit home when someone else is making money."

The Widener turned a circle, and the clammers in their bay-built workboats fell in behind for the ride out to the clear water of the bay. Miss Dottie led the pack, followed by Suspicious, Miss Audrey and Starlust.

A few moments later the skipper of another clam boat radioed from St. Michaels that he was coming out the Miles River to link up with the caravan. He was waiting in the main river when the fleet arrived.

It made for a rich spectacle, the Widener leading the five rough-and-tumble clammers down a narrow, winding track through miles of frozen waste.

The spectacle was soon overridden by an even richer aroma as Mate Jeff McDaniels set to work in the Widener's galley, frying up a mess of the Chesapeake's sweetest delicacy, softshell crabs, which he'd frozen last summer and saved for a special occasion.

At Crab Alley Creek the caravan was joined by a sixth clammer, My Lynn, which had crunched her way down through rotten ice from Kent Narrows. The half-dozen boats followed the leader for another mile until the clammers were in the clear waters of the bay. They would not go back home until spring, spending the rest of the season working out of Annapolis, where the Widener clears a path to open water for them each morning.

Only My Lynn's skipper called to say thanks, but some happy ensuing radio chatter among the watermen left the Widener's crew content that they had done their good deed for the day.

"How do you feel?" one waterman asked his mates.

"Like a duck," came the reply. "All this nice water . . . . "