HAVANA · American luxury yacht owners and rough-hewn sailors alike once dominated Cuba's regattas and fishing tournaments, navigating around U.S. travel restrictions through a loophole that allowed them to cruise legally if they could prove they hadn't spent a cent "trading with the enemy."

Armed with letters from Havana's Marina Hemingway generously waving all docking, visa and cruising permit fees, hundreds of American pleasure boaters sailed home from Cuba's forbidden shores claiming they had been "fully hosted" by the marina.

Federal agencies charged with enforcing the embargo didn't like it, but found the provision difficult to challenge without restricting Americans' freedom to travel.

Now under new, tighter travel restrictions meant to strangle Cuba's economy and precipitate the end of President Fidel Castro's 45-year rule, the Bush administration plans to eliminate the "fully hosted" provision as of June 30, a move many critics deride as a ploy aimed at pleasing Cuban American voters.

"It's an election year, I'm not surprised," said Craig Eubank, a Key West boat captain who has sailed to Cuba 37 times since 1994, often using the "fully hosted" provision.

Loading his galley with bologna sandwiches and cases of beer, Eubank attended Havana's semiannual Hemingway International Fishing Tournaments for years alongside as many as 50 other American boaters at a time.

This month he was one of only five Americans to attend the significantly scaled down event.

"The Bush administration scared everybody away, which is what they wanted to do," said Eubank, who this year traveled using a license to visit his 7-month old son in Havana.

The elimination of the "fully hosted" provision compounds other recent embargo-tightening measures, including a law announced in February, which expands the U.S. government's authority to inspect Cuba-bound vessels. Also, last week two Key West residents were charged with violating the embargo after they organized several regattas to Cuba.

"There has been a substantial decrease" from the 1,200 American boats -- roughly 60 percent of all vessels -- that used to dock at the Marina each year, said Commodore Jose Miguel Diaz Escrich, who helped found the Hemingway International Nautical Club, just west of Havana, 12 years ago.

In regulations published this week in the Federal Register, the Treasury Department said many Americans who claimed to be "fully hosted" had flaunted the rules by spending money in Cuba.

"Eliminating fully hosted travel -- which has the potential for abuse -- is an important step in stopping the flow of hard currency into Castro's coffers," Treasury spokeswoman Molly Millerwise said. "The Bush Administration is committed to hastening the day when the freedom-starved people of Cuba are able to live free lives."

Eubank agreed that boaters often do cross the fine legal line drawn by the "fully hosted" provision, sometimes staying in Havana hotels or eating in restaurants. But he argued that the embargo is obsolete as a tool to change Cuba's system.

"I'm not sure I know of anyone that was truly fully hosted," he said. "But it's not like Castro came out and took money out of people's pockets. That money went into the community, it trickled down."

Diaz Escrich, who signed many of the letters that once served as proof that American boaters had been "fully hosted," said the Marina Hemingway was happy to waive U.S. boaters' fees even if it meant lost revenue.

"You don't have to see advantages only in material gains," he said. "Our club has won in international prestige and in friendship."

With a view of the Marina's palm-lined canals, his office boasts mementos like the key to the city of Fort Lauderdale, given to him at a South Florida boat show in 1996 that speak to his ties to the U.S. boating community.

"In the Clinton era, despite all the regulations ... there was a certain flexibility," he said. "The saddest thing is, it's politics."

In addition to boaters, American business executives also took advantage of the "fully hosted" provision and several Cuba experts said they, not the boaters, were the likely targets of the regulation changes.

Robert Muse, a Washington-based attorney who has represented American companies with property claims against Cuba, said the new rules effectively prohibit not only spending money in Cuba but also traveling there.

"Clearly the administration is aware that there are cases that disfavor [legislating] where Americans can travel, so they have framed this within their existing authority to regulate [economic] transactions," Muse said. "It's been done artfully, but at the end of the day it's a per se prohibition of U.S. travel to Cuba."

Wayne Smith, a senior fellow at the Center for International Policy and former head of the U.S. Interest Section in Havana from 1979 to 1982, said relatively few Americans traveled to Cuba under the "fully hosted" provision. However, they may challenge the change.

"The Supreme Court after all decided the U.S. government could not tell an American citizen that he or she cannot travel to a given country," said Smith, a frequent critic of U.S. sanctions on Cuba.

In addition to eliminating the "fully hosted" provision, the new rules, based on recommendations announced on May 6 by the Bush administration's Commission for Assistance to a Free Cuba, have also clamped down on other aspects of travel to Cuba.

Cuban Americans, who were previously allowed to visit their relatives on the island once a year will only be able to go to Cuba once every three years. Their stay in Cuba will be limited to two weeks and they can spend only $50 a day, down from $167.

Students seeking to participate in an academic exchange program in Cuba must be enrolled at a college or university that has a Treasury Department license for travel to Cuba. They can no longer travel under the license of another institution sponsoring the exchange program. Exchange programs must be at least 10 weeks long. Currently, many programs are shorter.

Licensed travelers, who were once able to bring $100 worth of Cuban merchandise back to the United States, will not be able to bring any merchandise. Luggage will be limited to 44 pounds.

Cuban American legislators, who feel regattas to Cuba mock those who lost their lives in the Florida Straits while trying to escape the island, hailed the new measures, saying the Bush administration is matching anti-Castro rhetoric with action.

Rep. Lincoln Diaz Balart, R-Miami, called Bush "the best friend the cause of freedom for Cuba has ever had in the White House."

But in Key West, boaters scoffed at the new policies.

"It doesn't make me feel very free," said charter boat captain Joe Mercurio who has been "fully hosted" to participate in about 10 fishing tournaments at the Marina Hemingway. "I guess we don't have a president who has the intestinal fortitude to lift the embargo."