Nearly one week after the world's first collision of fully loaded supertankers, one of the ships has been saved but the other fights a race against time and sea.

One hundred miles north of Trinidad and 80 miles southeast of Barbados, the mammoth, listing hulk of the Atlantic Express wallows wracked by

Around the immense, crippled ship -- which stretches more than one-fifth of a mile from bow to stern -- labor six ocean-going salvage tugs, spraying the heat-buckled deck with water and foam. Trailing from its starboard stern quarter, 30,000 square feet of oil-soaked ocean blazes, billowing greasy smoke. Beyond that the azure Caribbean rolls stained for 50 miles.

Since her still unexplained collision off Tobago last Thursdaay night with the 11-year-old Liberian supertanker Aegean Captain, the Atlantic Express has been the focus of the greater concern among oil officials, ship agents and insurance brokers.

The Aegean Captain was not badly damaged. Salvage tugs dowsed its fire not long after they arrived on the scene Friday night and took the vessel in tow.

According to Trinidad government and oil company officials, 90 percent of its 1.5 million barrel cargo is still aboard. Officials believe it can be repaired and continue toward its announced destination of Singapore.

The Atlantic Express, however, is another matter.

Of the 27 men missing and presumed dead in the collison, 26 were crewmen. No trace of the missing has been found.

The captain is in a special hospital unit in Galveston, Tex., in critical condition with seared lungs and burns over 50 percent of his body.

The liberian-flag vessel is losing crude oil at the estimated rate of 350 barrels an hour, feeding the fire that licks at its flanks and threatenss to blast its 20 cavernous tanks apart.

Originally gashed by the collision along four starboard tanks, the Empress has been further weakened by explosiion and fire.

Monday night, what salvage officials called a "moderate explosion" occurred. Although Dick Fredericks, operation manager for the Dutch Smit salvage firm, said it would be a mistake to attach too much significance to the blast. "We can assume there have been others," he said, noting he could no longer guarantee the integrity of the ship's center tanks -- largest and most critical to the vessel's structure and stability.

He and Phillip Neal, a Mobil Oil Corp expert, conceded that in a heavy sea the vast tonnage of the 1,139-foot vessel's oil-filled bow section, working against the weight of the deckhouse superstructure and engine astern, would generate tremendous pressures on the weaken tank area in between -- pressures that could break the ship in two.

Neither Neal nor Fredericks would estimate how long the Atlantic Empress could remain afloat suffering continued fires and explosions and the punishment of the sea.

A key factor, they said, is the work of salvage crews, who have been working aboard in spite of a 15-degree list, on decks covered with fire, smoke and oil, pouring foam on the flames. As of last night, however, salvage and oil company officials postponed the effort and said they would try again this weekend with new supplies of foam, chemicals and equipment.

Michael Garnett, a burly English pollution troubleshooter for a consortium of tanker companies flew over the vessel Tuesday and said at least five men were visible on the deck working with foam, clambering around the perilous surfaces without even wearing lifejackets.

"It was the most astonishing thing I've even seen," Garnett said. "The men's bravery was absolutely astonishing."

Officials of Mobil, which owns the Emepress cargo, and those of the salvage companies involved think the work of such men can save the ship.

The fire on the vessel, which once engulfed virtually the entire haul, has been sharply reduced, they said, to about 10 percent of the deck area.

Neal said buckled deck plates and the scorched deckhouse show the Empress has already suffered the effects of tremendous heat "and if she was going to blow up she probably would have done so when it was worse."

Monday night's explosion Neal said, made matters worse. The fire on the water has spread, he said, and "I think they'll have trouble putting that out."

The tugs will need far more firefighting foam than they now have on hand, according to Neal. Once the vessel is cooled and stabilized, he and Fredericks said, the tugs will attempt to tow the ship into shelter so the cargo can be loaded into smaller tankers. The Empress is so huge, they said, it would take six or seven such ships to do the job.

Garnett estimated that at least 75 percent or about 1.6 million barrels, is still aboard.

Much of the remainder has burned he said, and what has spilled is being broken down rapidly under the combined action of the warm water, the sun and the microscope organisms that teem in tropical seas.

At its present position, he said, the Empress has been placed in a position where even the oil that has been spilled is "no danger to life or livelihood" or to any nearby land.

Fifty miles from the vessel, he said, nothing is left of the oil but a thin sheen. While that extends a considerable distance, he said, "It's harmless. . . . the sort of thing you might see in the sink when your wife washes the salad bowl."

Despite the size of the spill, he said there has been "no significant pollution" so far because "nature is taking care of it and nature does it far better than we can. It's man who tends to muck things up."

Asked what would happen if the ship broke up and sank in its present position, where the pressures of 900 fathom depths (5,400 feet) could crush her tanks, releasing all the cargo at once, Garnett said:

"It would be a much bigger spill, obviously . . . but even with that I would say there is a very high chance nature would take of it.

"It is just blind luck," he continued. "Had this happened in colder regions like the North Atlantic, or closer to some land mass, or had the salvage vessels taken longer to reach the ship, we might have had an entirely difference situation. CAPTION: Map, no caption, By Richard Furno -- The Washington Post