The Harvard sailing team, competing in three major regattas in one weekend, successfully defended the Jack Wood Trophy and took seconds in the Big Three regatta and the Franklin J. Lane Trophy.

Abbott Reeve and captain Joe Worth in Division A and David Little and Charlie Koch in Division B took low-point crew honors in the pentagonal Wood Trophy, held Sunday on the Charles.

John Bowers and Rud Istvan survived an early scare to finish second in the JV division, while Peter Belknap and Chris Middendonf had a disastrous day in the Freshman division.

The Wood Trophy, the oldest of all intercollegiate sailing events, uses the British system of co-skippers sailing alternate races and calls for four crews. "This really puts the emphasis on depth." sailor Phil DeNormandie said last night. "Most teams aren't used to using so many skippers on the same day. Harvard schedules heavily each weekend and develops many experienced sailors," he added.

Harvard, the 1969 champion, collected only 136 points to walk away from second-place M.I.T. with 168 and third place Dartmouth with 181.

The sailing team set the stage for the Wood Trophy victory with a disappointing second behind Yale and ahead of Princeton in the Big Three Regatta Saturday at New Haven.

The Big Three Regatta, also known as the Knapp Cup, is a one-division team race in which each college enters three two-man crews. "This necessarily introduces team tactics, rarely seen in intercollegiate sailing," sailor Doug Allen said.

Harvard's crews in the Big Three were Abbott Reeve and John Roberts; Joe Worth and George Putnam; and David Little and David Brownlee.

Sailing in their home waters and in their own 420's. a centerboard sloop, the Elis proved to have an advantage over Harvard, accustomed to the jib-less Interclub dinghys and the stormy Charles.

The team's third regatta of the weekend was the Franklin J. Lane Trophy at Tufts on Sunday. The Crimson, quickly behind because of a slow start, steadily closed the gap and only narrowly missed first place after fine helmsmanship by Doug Allen and Steve Glovinsky.

Tufts won the trophy with 35 points to 39 for Harvard and 46 for third-place B.U.