The sea surrounding the Coast Guard cutter Madrona, docked at Pier 3 in Baltimore Harbor at 7:15 a.m., looked cold and white and motionless. So did the Madrona's crew.

"They look like a bunch of zombies out there," the ship's executive officer said to Lt. Cdr. Warren C. Hoyt, captain of the ship.

The Madrona had come in the evening before from Portsmouth, Va., and a night's liberty on The Block (Baltimore's celebrated strip of porno shops, bars and prostitutes) left the crew with queasy stomachs, leaden heads and memories that would grow more vivid as the day wore on.

Fifteen minutes later, the Madrona was steaming out to sea, on the second day of a special mission to repair ice-ravaged buoys in the Chesapeake Bay and to plow through the frozen crust that was hindering harbor traffic.

The 30-year-old Madrona belies the traditional image of the Coast Guard ship, an image of a white vessel loaded with white uniforms sailing off on white-knighted missions to aid hapless craft. It is a buoy tender, a 180-foot black hulled vessel whose decks, after a slow start, are filled with men in grimy work clothes and hard hats operating booms and wielding axes.

With 220 buoys to keep in shape and in place from Portsmouth to the Patuxent River, the Madrona and its men are the road crew of the Chesapeake Bay.

According to Hoyt, this winter had marked the first time in 10 years the Coast Guard has had to detail any ice-breaking missions in the Bay, and the crew had clearly relished its first confrontation with the task on the way up to Baltimore. The Madrona's reinforced steel bull is specially constructed to slide up onto thick ice and break it up with the weight of the ship.

Most of the ice encountered by the vessel was less than one foot thick and the Madrona simply plowed its way through, breaking the ice into quarter mile long chunks that eventually would drift out to sea.

By Saturday, most of the ice in the Madrona's jurisdiction posed little threat to commercial vessels, but the threat from missing or ice-encursted buoys remained.

Seen through the eyes of the Madrona's 53-man crew, the Bay loses much of its mysterious and trackless romance and begins to look like a rather large but eminently definable network of highways and roadsigns.The Madrona, for instance, spent most of its time in Brewerton and Craighill channels, two of the most heavily-travelled routes into the Bay from the ocean beyond, roadways where the water is deep enough and the way unhindered.

The buoys mark the borders of these channels, preventing large ships from straying into more shallow waters where shoals and sandbars might cause them to run aground.

On a neatly pencilled list in the ship's bridge, was a list of about 25 buoys that needed fixing. Their lights were put out when they had been dragged under water by the weight of the ice or pulled off course by sheets of ice drifting out to sea.

One such buoy lay on the Madrona's deck, its red paint onscured beneath a deep curst of ice and snow that the "deck apes," as they are known to those with warmer jobs inside the ship, were busy scraping and steaming off. Seven feet high, weighing six and a half tons, with a concrete sinker weighing another 12 tons, the buoy would be cleaned, relighted and placed back in position according to calculations made by sextant and chart readings by the vessel's earnest young ensigns.

By early afternoon, the Madrona had reached Charley One, the buoy that marked the beginning of the Craighill channel.

Locked in ice, tilted stiffly at a 45-degree angle to the ocean, it had drifted about 100 yards from its charted position. It took the Madrona over an hour to break up the ice that had imprisoned it, swing near enough to permit a crew member to clamber atop and repair the light and tow it back to where it belonged.

Lt. Cmdr. Hoyt shook his head. "In six or eight hours," he said, "the damn thing will be under way again," another entry on the "discrepancy" list to be repaired once again.

So it would go throughout the long and cold 12-hour day. There were reports of a foot of ice near the Chesapeake Bay Bridge, but the Madrona arrived to find the water clear, clam and glassy in the sun. There were reports of a tanker caught on a shoal near Seven Ft. Knoll Lighthouse, but they arrived to find two tugs had pushed it off. Its 12,000 tons of fuel were still within the confines of the ship.

By the end of the day, they had serviced and returned to place five buoys. They faced two or three more days of the same before heading up the Potomac River to clear the way for oil tankers that were finding it difficult to make it to Alexandria with loads of heating fuel.

The hard, tedious, repititious nature of their work does not seem to bother the Madrona's crew. They look on their labor as being above the more leisurely endeavors of "the white fleet," which spends most of its time patrolling or on search and rescue missions. The black hulls, says Hoyt, echoing many of his men, are "the workers of the fleet."

As the Madrona steams slowly through cracked sheets of ice from one buoy to another, the enlisted members of the crew gather below deck, out of reach of the cold wind and the commanding officers.

Most of them are young, native sons of small towns and cities far from either coast. Now, home in the narrow confines of the Madrona, where they eat, sleep and work, and from which they cannot leave without checking in every three hours, even on weekends.

It was not the romance of the sea that signed them up for a four-year hitch, most say, but a last-ditch attempt to avoid the unemployment rolls or the assembly line.

"The day after I graduated from high school," says Martin Suttles, 22 of Detroit, "I spent 12 hours working in a factory. I knew I couldn't do that for the rest of my life. I went downtown and the Air Force office was closed. I joined the Coast Guard."

For some, like Stephen Fultz, 22, of Mississippi, the hard work and military aspects of life in the Coast Guard came as something of a shock. "I was out of high school and couldn't find a job," says Fultz. "I thought the Coast Guard didn't really to anything and I'd never seen the ocean. Little did I know.

"After several encounters with military discipline and the Guard's rather negative attitude toward marijuana, Fultz is counting the days - "a year and nine months 'til it's over," he says.

As they talk male pride eggs them on to outdo each other in tough-taling cynicism about their work, and the limited possibilities on land that drove them out to sea. There are complaints about the work, the pay, about each other. "The first two days out to sea, they're fine," says Yeoman 2d Class, Thomas Williams. "After that, you just be sure not even to look at someone the wrong way."

By now the air is heavy with cigarette smoke and cynicism, but the tide around the table shifts abruptly once the Navy is mentioned. "The Navy calls the Coast Guard the hooligan's navy," they say. "But they're just jealous because we get home more often." Besides, says Lindy (Doc) Warner, who takes care of the ship's medical supplies, "we're always working."

Then come the tales of the rescues they've made, of the times the crew collected itself from shore leave in an hour and a half and put out to sea in an emergency, and talk of the image that ordinary mortals have of the Coast Guard. "There's this picture people have of the Coast Guard as the good guys," says Alan Jorgensen.

"Maybe you don't admit it to yourself, but you come in to be a hero."

Soon the lights of Baltimore come into view, glinting in the night like bourbon in a shot glass. Lt. Cmdr. Hoyt, winner of a Purple Heart and two Bronze Stars, hopes his crew will return safely. "Oh, I warn them about getting their teeth kicked in, or getting a knife stuck in the back instead of what they expect, but they're good men. The beer, the hookers, the music, it gives the crew a little morale."

Ensigns David Cline and Michael Anderson, 22, fresh out of the Coast Guard Academy, prepare to meet their wives who have driven up from Portsmouth. Doc Warner and his confederates set out on a quest for a young lady by the name of "B.J." who, to hear them tell it, is quickly becoming the stuff of which legends are made.

The gripes below deck have disappeared with the sea breeze. "Ah, the Coast Guard," sighs a disembodied voice. "It's the only way to travel."