Once upon a time the weekend races in April served merely as a tuneup for the Harvard heavyweight crew. The Crimson would routinely swamp all competition leading up to the Eastern Sprints in May, whereupon Harvard's performance would either seal of doom an undefeated season.

Unfortunately for Coach Harry Parker and the Varsity Eight, the days of Harvard's dynasty are gone Party is very much in style in men's crew of the 1980s, and Princeton made the fact abundantly clear on the smooth waters of Lake Carnegie in New Jersey Saturday.

Riding a tailwind in perfect rowing conditions, the Tigers surprised everyone but themselves by stroking past the Crimson varsity in the last 500 meters for a half-boatlength victory, hammering one final nail into the Harvard dynasty's coffin.

By upsetting the Crimson, Princeton gained the Compton Cup for the first time in over a quarter century, while MIT, the last non-Harvard winner in 1962, finished a distant third.

The ideal water conditions produced very fast times over the 2000-meter course The Crimson got off to its characteristically fast start, establishing nearly a boatlength lead at the 800 meter mark.

Meanwhile, the Tigers, rowing at a lower stroke cadence, conserved their strength for the second half of the race. The strength paid off when Princeton started rowing through the Harvard boat in the last 1000 meters, eventually edging the Crimson by two seconds.

"They rowed a more cagey race," Harvard coxswain Dan Simon said yesterday. "They were confident of their strength and their ability to make a late move."

Although Princeton had a strong showing in last year's Eastern Sprints, the Tigers had not had much success in the early season regattas until Saturday.

"We rowed a really strong race Saturday Princeton still beat us," Harvard six-man Paul Jeffrey said yesterday. "I think they're definitely for real."

The Harvard lightweight crews fared much better than the heavies Saturday, easily sweeping all six races against Navy on the Sevem River in Maryland.

Especially impressive were the varsity lights, who rebounded after last week's loss to MIT by outstanding the Midshipmen by a hefty three boatlengths.

Taking advantage of the first calm waters in three weekends of rowing, the Harvard lights grabbed a halflength lead after 500 meters and gradually extended it over the 2000-meter course Navy never mounted a challenge as the Crimson boat finished in 6:10.2.

The win iced the Haines Cup for the Crimson for the 50th time in 17 years.

"We learned our lesson about taking opponents lightly last week against MIT. I guess we redeemed ourselves," Crimson three-man Ed Fleming said yesterday.

Saturday's sinking of the Midshipmen, upping Harvard's season slate to 3-1, allows the oarsmen to enter next Saturday's important Harvard-Yale-Princeton race on a positive note The New Jersey regatta will doubtless provide the Crimson lights with stiff competition Earlier this season Princeton beat Navy by a bigger margin than the Crimson, and Yale is expected to be equally tough.