Some gatherings in Washington are perennial. Last night at the International Ballroom of the Washington Hilton, almost 800 people gathered at the 20th HOPE Ball to pay a $150-a-plate tribute to Project HOPE, the now land-based health program that started 24 years ago aboard the teaching hospital ship the S.S. HOPE.

There were no speeches, no awards--just the elite of Washington society.

"There's our whole cabinet," said ball vice chair Ruthanna Weber, eyeing a tight circle formed by Secretary of State George P. Shultz and his wife Helena, Secretary of Defense Caspar W. Weinberger and Secretary of the Treasury Donald T. Regan. Cabinet members Richard S. Schweiker, John R. Block and Raymond J. Donovan were working their way through the crowded ballroom.

"And they've all worked so hard for HOPE," added Weber, in reference to contributions of Cabinet members' wives to HOPE. "They've done everything, even stuffed envelopes."

Inside the doorway, Project HOPE founder and president Dr. William Walsh, Weber and ball vice chair Ann McInerny, assisted at times by ball chairwoman Nancy Thurmond, greeted the winding line of guests who included Organization of American States Secretary General Alejandro Orfila and Jamaican Ambassador Keith Johnson.

"We supported HOPE when we where here in Washington before. We supported it when we were in California, and we support it now," Shultz said.

"They like what HOPE does," said Walsh, modestly surveying the room.

"He conned Eisenhower into giving him the ship," said one admirer of Walsh's project, "and he's done more for the American image abroad than any one of those check-passers."

"We are not in bad times," Shultz said, commenting on what he judged to be a good turnout. While other guests said many fund-raising committees have experienced poor turnouts because of the recession, Shultz maintained the Reagan administration's position that the economy is on the upswing. "As evidenced by the number of people here, things are better.

"I want to dance with my wife now," he added, exiting abruptly for the dance floor.