Men used to take to the sea in boats to find treasure in far away countries or escape problems in the one at hand. Only God and rowers know why nearly 2000 people will shove off from docks at boat houses along the Charles Sunday to race in this year's version of the Head of the Charles.

In all, 720 crews will compete in 18 events--40 boats in each event--starting with the masters' singles race at 9:30 a.m. and ending with the men's championship eights at 4:30 in the afternoon, with a parade of single-skulls, double skulls, fours, and eights at all hours in between.

Depending on the weather, which various sources have prayerfully predicted will be sunny, warm, and beautiful, upwards of 100,000 spectators could line the banks of the Charles to watch crews from all over the United States and Canada--as well as a smattering of crews from Europe and Asia--compete against the clock rather than each other.

Unlike sprints, where boats line up bow to bow and race for 2000 meters along a straight course with the first one across the finish line declared the winner, boats in each event in the Head start at ten-second intervals and race 5000 meters (about three miles) upstream from the down-stream edge of the Boston University boat house (in the Charles River Basin) to a point in the Metropolitan District Commission park near the Ramada Inn. Keeping track of the times and comparing them, a computer can then show who won the particular event.

This year's Head is again being sponsored by the Cambridge Boat Club, the group that organized the first Head 17 years ago and has been running it ever since.

One of the reasons there aren't more crews from Europe in the race, according to Jerry Olrich, an official at the Cambridge Boat Club, is that rowing is still not a fall sport in Europe. But, Ulrich continued, rowing wasn't considered a fall sport in the United States until the Head of the Charles.

The idea, Olrich said, was "to take up the slack on racing in the fall." In the first Head of the Charles--the first head race in the country--100 boats took part. At first, Olrich said, the Ivy League refused to allow rowers to participate, afraid it would set a dangerous precedent for off-season competition. And so, ever resourceful, Harvard oarsmen formed independent rowing clubs (usually associated with their Houses, Olrich said) to enter boats in the Head. The league's athletic directors relented, and so rowers can now represent Harvard and Radcliffe.

Out of the 18 events in the regatta, three are for men only and three are for women only: the men's and women's championship singles, championship fours, and championship eights. In each of the other 12 events, with one exception, men and women race against the clock together, their times computed and ranked separately.

In the exception, mixed eights of four men and four women compete against each other. Harvard and Radcliffe lightweights will row in the schools' entry again this year, competing for the most part against mixed crews manned by heavy-weight oarsmen and women.

Unlike some schools who have been in session longer and whose crews have had more time to train, Harvard and Radcliffe tend to have a more relaxed attitude about the Head. This is by no means to say that the people who will be rowing Sunday won't be out to row as hard as they can.

Cary Graves, coach of the Radcliffe heavyweights, said it "would be rather ridiculous" to try to put together a varsity boat this early in the season. Rather, Graves said, the race has "a lot of social significance for people who row on the river."

Beyond the excitement of rowing in front of the hometown crowd, racing in the Head helps keep rowers--whose season is still six months away--interested in their daily training regimen, Bruce Beall, the coach of the Harvard lightweights, said while he wished the Head were later in the fall, he didn't think his crews would be training any differently if there were no Head. "It gives a goal, an impetus for training," he added.

The thrill of racing and the applause and cheers the crowd hurls at the boats as they go by certainly gives most rowers a vague idea of why they row. For some, rowing revolves around the extremes of love and hate. Phil Nichols, a member of the senior lightweight eight Harvard has entered in this year's lightweight race, put it tersely: "I hate crew, but the Head's great."

If the demand for a spot in the Head is any indication, then many others apparently share Nichol's affection for the race.

Olrich said the regatta committee had to turn away 300 applications for spots in this year's regatta. One 71-year-old skuller from Oakland, Calif., Olrich said, has flown to Cambridge in the hope that someone in the masters' singles race will have to withdraw, leaving him a place in the race. Ulrich added that there were already three others waiting for that same spot should it open up.