Dawn in the Windward Passage, the sea scarcely ri ppling in the windless air.

West of the ship the mountains of eastern Cuba brood on the horizon as the Saint Petersburg rumbles along, sea foam streaking from her bow. To the east the rising sun glows over Haiti - Cape Saint Nicholas and Cape du Mole gilded under a crown of orange clouds.

This was the route of the slave ships which, like the oil tankers of today, sailed from the Carribbean freighted with energy and disturbing questions for the society they served.

Last year tankers carried 6.3 million barrels of oil to the United States every day, or roughly 37 per cent of the nation's total oil consumption.

Roughly 40 per cent of that traveled through the huge refineries and trans-shipping points in the Caribbean, an area whose strategic location and deep-water loading facilities have proved increasingly attractive for the deep-draft supertankers ferrying crude oil from the Persian Gulf.

Smaller ships like the Saint Petersburg then relay the oil north to the harbors of the East Coast, harbors too shallow for the superships, which may reach 75 feet beneath the sea.

To Trinidad (Texaco), Curacao (Shell), St. Croix (Hess) and other islands the oil ships stream in increasing numbers, their squat, rust-streaked hulls intruding on the pastel Carribbean seascape like flaws in a jewel.

When the Saint Petersburg left Aruba, 11 other tankers anchored there were waiting their turn at the pipes of Exxon's giant Lago Refinery, where some 1,500 tankers put in for oil in an average year.

Oil men say that increasing traffic is one reason for opening the East Coast to supertankers, either through deeper channels inexisting harbors or deep-water loading facilities for the mammoth ships ofshore.

A Very Large Crude Carrier (VLCC) like the 400,000-ton Esso Japan, for example, can carry more oil in a single voyage that the Saint Petersburg can in 10 Fewer voyages, the oil men say, mean fewer chances for the human errors on which most tanker accidents and oil spills are blamed.

Critics of the big ships, including Noel Moslert, author of the 1974 book "Supership," charge that supertankers are overautomated and undermanned and operate on a disturbingly thin margin of safety. That margin, they say, will grow ever thinner in the next few years as the big ships built in the 1960s reach the halfway point in their projected 20-year life.

Coast Geard officers charged with policing the tanker trade, however, say it is rarely the size or type of tanker or its flag of registry that marks the difference between a good ship and an unsafe, potential polluter.

That difference, they say, lies in the owner and the crew.

As the Saint Petersburg sailed through the Windward Passage and headed north toward San Salvador, her crew was not doing much. It was Sunday, when nonessential shipboard routine is put by for the day.

During the morning Capt. Giuseppe Neri made an inspection tour of the ship, poking around with the easy air of a foot policeman out for a stroll in a friendly neighborhood.

He had words for the chief mate when he found a fire nozzle stowed behind its hose out of sight, but he paused with pleasure, hands on hips, in the misty air of the galley freezer.

"Cook this is really very nice," he said to Chief Cook Marcelino Corputz, 41. "I don't think I have ever seen a refregerator so clean.

Later, over a light pre-lunch martini in his cabin, he observed the weightiest ritual of this ship's Sunday: reviewing the Italian soccer league scores, received by radio from Rome.

Neri, 46 is a railway worker's son from Ancona, a coastal city in north-eastern Italy. He is a product of five years of nautical high school In Italy, three years apprenticeship as a maritime cadet and nearly 20 years as mate and master.

Though most of the Saint Petersburg's crew is Filipino, its top five of ficers are Italian, in part, Exxon said because Itallians are some of the company's best and most experienced seamen.

Italian crews can be hired for about half the cost of an American crew, according to Capt. G.S. Salveson, who manages about 15 tankers for Exxon. Filipino crews, he said, work for about half the pay of Italians.

Exxon, Salveson said, began hiring in the Philippines only relatively recently, however, and while some whips have Filipino captains, most potential officers are still working their way up through Exxon's tanker organization.

Italians and Filipinos work well together, Salveson said; not all other nationalities do.

"A Filipino crew for me is better than an Italian crew," Neri said over Sudnay lunch of spaghetti with meat sauce, fried squid and filet mignon. Italians always argue and want overtime. Filipinos and Indians are good fellows. They follow you around waiting for orders."

Which nationality has the worst seamen?

"Well maybe it's just me," said Chief Mate Sergio Ischiale, "but if I see ship coming with Greek at helm, i give him lot of room."

The Saint Petersburg herself had plenty of room as she made her way northward through a warm, lazy sea south of the Bahamas.

Neri's course had carried her northwest along the Cuban coast briefly, then northerly past Great Inagua and Crooked Island.

On the afterdeck, Arnulfo Bondoc, 29, the Saint Petersburg's electrician, smoked a cigarette and talked about different ships and different masters.

Bondoc served several months on a 30,000-ton Aristotle Onassis tanker called the Andros City, withe Greek officers and a crew of Filipinos and Indians.

"The Greeks gave us not safety equipment, no cold-weather clothing, no antipollution training, nothing," he said. "Exxon sees we get all those things."

Able Seaman Filomeno Lerieas, 26, however, spent 2 1/2 years on a 120,000-ton Onassis tanker called the Chryssi P. Goulandris with Greek officers and a crew of "Arabs, Indians, Filipinos, all mixed up." It was a good ship, he said, with a good captain. Safety equipment was provided and some pollution traning.

The international makeup of crews on modern tankers causes some problems, but none, Salveson said, that cannot be licked by training. English is the international language of the sea.

But dinner subjects know no national boundaries. The Italian officers debated the merits of Fellini films, cars, the future of soccer in Europe and where Capt. Nero will go to ski on his vacation.

After dinner the officers watched Steve Mc Queen ride rodeo bulls in a movie called "Junior Bonner," shown via video cassette on the television set in the lounge.

Then First Engineer Giuseppe Di Donna, 34, retired to his cabin with a couple of friends to open a bottle of very fine Remy Martin cognac and talk of shipboard life.

Di Donna, an engaging character hauling two model battleships and an electric train home to Italy for his daughter, reminished about his bachelor days on a cargo ship.

Once, he sighed, on a run to Russia in the early 1960s he encountered a sailor's dream: a city full of women with virtually no men.

"All we talk about is women," said Chief Mate Sergio Ischiale.

"Talking about women isn't the problem," said Di Donna. "THINKING about women - that's the problem."

Women are both more accessible and more remote on modern tankers than in ships of former days. Many companies allow wives to accompany their husbands on board for months at a time, but there were none on the Saint Petersburg. The high cost of getting to where the ship is keeps most wives at home. Tankermen themselves rarely get any time ashore except for vacations.

Even when the usual 12-to-24 hour turnaround time in port is delayed for some reason there's rarely anywhere to go: Modern tankers usually tie up at the end of some oil pipe somewhere remote from the nearest town.

Said bosun Arturo Veneracion, 34: "This must be the loneliest job in the world."

At 10 p.m. the night had turned to showers and mist, radio operator Margarito Nueros, 36: stood staring through the bridge windows into the darkness.

He started talking about heavy weather ahead and puzzled over the Panamanian tanker Grand Zenith that had disapppeared off Nova Scotia earlier in the month.

"There was no SOS," he said. "Why was there no oil slick?"

The Saint Petersburg, he said, would enter the Bermuda Triangle the following day.

"I notice when we're sailing there, the radio signals are very faint, Why is that, do you suppose?"

Outside the mist what looked like the distant lights of another ship appeared faintly out of the twilight zone. But it was only the Saint Petersburg's how light pointing her way out of the island and back to winter.

NEXT: Handling a tanker's cargo .