Fifty-two yachts and motor cruisers from the United States sailed into Cuba's main resort of Varadero yesterday, one of the most conspicuous displays to date of the new climate between the two nations.

The boats carried about 250 Americans bound for luxury vacations, something Americans haven't been able to spend in Cuba for nearly 20 years.

The U.S. pleasure flotilla, however, represented something of an irony of international politics.

Tourism from the United States is again becoming commonplace, thanks matched on the diplomatic front.

President Carter in an interview Friday with Hospanic editors accused Premier Fidel Castro of trying to "subvert other people [governments ] through military means" and of being "used by the Soviet Union" to thwart peaceful settlements of disputes in Africa and the Middle East.

The President also accused Castro of being a major violator of human rights. "Castro has thousands of political prisoners still in jail," he said, "I don't think that our relationships with Cuba are going to improve any further unless he shows in tangible form he is committed both to peace and the enhancement of human rights,"

On two counts, Carter accused Cuba's leaders of being less than forthright.

In the first case, Carter implied that the Cuban people were not being fully appraised of Cuban troop losses in Africa.

"Cuban troop losses in Africa have recently been quite high," Carter said. "And I am not sure that the Cuban people know how severe the loss of life is among Cuban troops that are sent to Angola, nor among the ones sent to Ethiopa."

In the second case, Carter said Cuban leaders "would like to have the image of being a nonaligned country."

"But that is obviously and absolutely a ridiculous claim because there is no other country that acts in harmony with and under the domination of the Soviets any more than the Cubans do," Carter said.

He added: "They are completely aligned with the Soviets, and where most of the nonaligned countries seek peace and peaceful settlements of disputes, the Cubans are at the forefront of the cutting edge of providing military forces in areas of Africa, for instance, (and) wherever they possibly can find an opening."

The importance or lack of importance of Carter's remarks apparently made no difference to the American vacationers who arrived at Varadero yesterday.

"The best way to get along with people is to get to know them and to get them to know you," Fred Freeman, a retired aviation official from Ocean City, N.J., told the Reuter news service. "We've got to get rid of this ugly American image we create around the world."