By the dawn's early light--5:45 a.m.--parents are dropping off groggy teen-agers at the Potomac's edge, near a boathouse behind the crumbling remains of the Torpedo Factory in Old Town Alexandria.

By 6 a.m., dozens of T.C. Williams High School students are gliding on the river's current in slim, glistening shells, the eight- and four-person teams straining to dip their oars swiftly and pull smoothly in unison.

That's life every spring if you're on a crew team.

For more than 30 years, a small number of area schools, led by arch rivals Alexandria's T.C. Williams and Arlington's Washington-Lee, have been going down to the river in shells. They've brought home scores of national titles and sent a number of athletes on to England's famed Henley Royal Regatta and the Olympics.

Northern Virginia's seven high school crew teams are the only high school teams in the Washington metropolitan area. They share the waters of the Potomac River and Occoquan Reservoir only with college teams and a few rowing clubs.

To this year's crop of about 500 students on the local teams, the daily regimen of practice under often less-than-perfect conditions is a time-honored tradition.

"It's a love-hate relationship," said Ann Czaja, a T.C. Williams girls' varsity team member who has just been awarded a full-tuition crew scholarship to Syracuse University. "But there is something about it when that eight clicks and you are all rowing together. It's beautiful."

"Crew is the ultimate team sport," said Charles Butt, head coach at Washington-Lee since 1949 and sometimes called the father of Northern Virginia crew. "It's hard work, but the rewards are plentiful."

High school crews usually compete in four types of boats: four-oared shells, eight-oared shells, single sculls and double sculls. In the four and eight boats, each rower wields one oar, in a style called sweep rowing. In sculling, rowers use two oars each. In the larger boats, a coxswain--someone who weighs no more than 115 pounds--steers and acts as a kind of coach within the boat, calling out strategy and the rowing cadence.

Most of the crew schools--Yorktown and Washington-Lee in Arlington, Fort Hunt and J.E.B. Stuart in Fairfax County, and Woodbridge and Potomac in Prince William County--have between 30 and 80 boys and girls in crew programs this year.

But in Alexandria, crew is more popular. T.C. Williams has about 100 boys and 100 girls on its team this year, making it the school's major athletic activity and one of the largest crew programs in the country. The team has $350,000 worth of equipment, and has so many trophies from its 37 crew seasons that the school is running out of space to display them.

"It's one of those things. Once you've got the bug it's contagious, and once you are hooked, you're hooked forever," said T.C. Williams athletic director Donald J. Riviere.

The T.C. Williams team, which has 10 coaches, practices either at the crack of dawn or in the late afternoon, just after school. For the boys' varsity and junior varsity teams, the sun is usually just rising when head coach Bob Spousta heads the boats past Crystal City and National Airport, dodging debris on the Potomac.

Spousta's team begins on-the-water practice in February, though most of the athletes keep in shape all year by running or compet ing in other sports. Though crew races are usually 1500 meters and last four to six minutes, they demand a tremendous outpouring of energy and hours of practice. Spousta and coaches of the other programs operate on a "no cut" policy. "There's a place for every kid who is serious about it," said Spousta. He added that any teen-ager willing to stick out the grueling practice schedule (and able to pass a swimming test) is placed in a boat.

"A crew team is different from a basketball team, where five people do all the playing and most people sit on the sidelines the rest of the season," said Steve Weir, T.C. Williams assistant girls' coach.

Other students are often amazed at the rigors their classmates on the crew team go through: that by the time they come to an 8 a.m. class, they already have spent two hours on the river, changed clothes and arrived at school.

"A lot of my friends ask me how I stand the schedule," said Julie Bartick, 17, at 5:35 one morning last week at the T.C. Williams boathouse at the foot of Cameron Street. "They don't know how nice it is out there on the water."

"Coming down here every morning at 5 a.m. is hard," said David Marson, a junior varsity rower from T.C. Williams. "I try to go to bed by 10 every night."

Classmates often don't give crew the recognition that other sports get. "I wish we had more support from the school," said Billy Kost, a T.C. Williams varsity rower. "Everyone gets psyched for basketball and football. We had four national championships last year in crew."

The history and tradition of the crew team in Alexandria is a big drawing card for the program. "It's probably the hardest sport you can do," said Glen Breeding, T.C. Williams junior varsity rower. "But I like the fact that it's an old sport, and the tradition of it. I would love to go to a rowing college."

A number of students from T.C. Williams, which won the Northern Division rowing championships last weekend, and other area high schools have received rowing scholarships. Tony Johnson, who was captain of Washington-Lee's 1958 crew team, was on the first Arlington crew to go to the Henley Regatta, rowed in two Olympics and is now head crew coach at Yale.

Although Fairfax County crew teams are run as club sports with no financial support from the School Board, Alexandria's crew at T.C. Williams, the city's only high school, is a varsity sport, with the school system paying for coaching and most transportation costs.

Equipment is also expensive. A new eight-oared shell costs about $8,000--one reason that the high schools that can afford crew usually have to rely on team fund-raising activities and parents' booster clubs for support.

Bob Gamba, president of the Fort Hunt Crew Boosters, comprising about 30 families, said his group raises money for the team through garage sales, auctions and an annual pumpkin sale. "The pumpkins we don't sell we later sell as pumpkin bread and pumpkin pie," said Gamba.

The Alexandria Crew Boosters, begun in 1950, have 150 members and last year raised more than $11,000--money that bought the T.C. Williams team a $3,900 video tape system, $2,050 worth of oars and a four-oared shell for $5,000. "If we didn't have the boosters, we wouldn't have a crew team," said John McCune, president of the Alexandria group. "This year we hope to raise enough to buy a new trailer for the boats."

John Gamba, a member of Fort Hunt's varsity four-man team, had never heard of crew when he moved to Fairfax two years ago from Virginia Beach. "Now I'm really crazy about it, though it takes a lot from you," he said. "When our team really works together, it's unbelievable."