The five men who took a voyage aboard the shrimping boat Santrina in March are now linked by intrigue, deception, federal charges and Cuban exile militant Luis Posada Carriles.

BY OSCAR CORRAL AND ALFONSO CHARDY

The lines of the Santrina are hardly the sort to quicken pulses; it's a simple shrimp boat, really, nothing more.

Yet this shrimper is freighted with the stuff of intrigue: suspected conspiracy plots, betrayal, a secret weapons cache linked to one of the shrimper's owners -- and an array of ties to Luis Posada Carriles, the CIA-trained, anti-Castro militant who has been accused of acts of terror.

The Santrina, described by its owners as a vessel for teaching diving and appreciation of the sea, floats idly on the work-a-day waters of the Miami River.

In March, it bobbed off Mexico's Caribbean coast -- just miles from where Posada said he plotted his politically combustible entry to the United States.

That mysterious voyage -- Fidel Castro claims the Santrina's mission was nothing less than to sneak Posada into Florida -- remains unexplained. The men who participated in it deny they had steamed to Isla Mujeres to pick up Posada. But they give differing accounts of what they were doing there. They are:

VOYAGERS

• Santiago Alvarez, 64, Posada's benefactor and one of the Santrina's owners. He is behind bars, following his arrest Nov. 19 on weapons charges for illegal possession of machine guns, ammunition, a silencer and grenade launcher, which the government says were kept at a Broward apartment complex Alvarez owns.

• Osvaldo Mitat, 63, employed by Alvarez as a handyman who helped with the upkeep of Alvarez's properties. He, too, is in jail, facing weapons charges. Both men have pleaded not guilty.

• The Santrina's captain, Jose Hilario ''Pepin'' Pujol, 76, who says he sailed to Cuba on another boat a decade ago in attempts to infiltrate two anti-revolutionaries into the island in a plot to kill Castro. The ploy ended with the two men behind bars in Cuba, convicted of attempted bombings in what Cuban officials have labeled a terror campaign they say was partially masterminded by Posada.

• Gilberto Abascal, 40, who cooperated with the federal government to turn state's evidence against Alvarez and Mitat, culminating in the pair's November arrests in South Florida. Abascal told The Miami Herald he did ``what I feel is right.''

• Ruben Lopez Castro, 67, owns the house where Posada is said to have stayed for about six weeks while he was in hiding in Miami and where Posada was detained May 17, friends said. Lopez Castro, reached by phone, declined to comment.

PUT TO THE TEST

The Posada case caused a firestorm in Miami this year, testing Washington's commitment to the war on terror, threatening diplomatic ties between the United States and one of its biggest oil providers, Venezuela, and jeopardizing President Bush's relationship to one of his most loyal Republican constituencies, the Cuban exile community.

The controversy began shortly after the Santrina visited Mexico and Posada appeared in Miami.

Five years earlier, Alvarez and other friends, including 42-year-old construction manager Ernesto Abreu, started Caribe Dive & Research Foundation, a nonprofit diving school they said was meant to increase students' appreciation of the sea.

In 2002, the group bought the Santrina, an old shrimping boat, in Louisiana and brought it down to Miami. During the boat's renovation, Pujol and Mitat met Abascal, whom Alvarez had hired as a welder to work on the Santrina. Pujol said Alvarez thought of the younger Abascal as a son.

Abascal, a Cuban immigrant, had arrived in the United States in the late 1990s. He developed a reputation as an accident-prone handyman who liked to talk about women, said Pujol and Abreu, who is listed as the president of Caribe.

''His conversations were always about things that had no importance, like women, or girlfriends,'' said Pujol of Abascal.

Alvarez asked Pujol to come teach boating classes to Caribe students. Pujol said that since Caribe opened, it has taught 20 to 30 people, but that Abascal never wanted to take the classes.

In mid-March, Alvarez and the others took the Santrina to the Bahamas and then headed west toward Isla Mujeres.

Posada acknowledged in a May interview he was in Cancún around the same time the Santrina was in Isla Mujeres, which is two miles north of Cancún.

DIFFERENT REASONS

But crew members and friends of Alvarez gave different reasons for the trip.

Pujol: ``To make contacts in Mexico to see if people wanted to train [to steer boats and dive] with us.''

Abreu: ``They had put a new propeller in and were testing it.''

Alvarez: ``We made contact with two or three people. I can't say that [the trip] had absolutely nothing to do with Posada because I've been in touch with him for years, but I can say that I didn't bring him. Santrina didn't bring him.''

The one-day trip to Isla Mujeres underscored Abascal's lack of sea legs, Pujol said. Seasick, Abascal curled up in a cabin below deck on the 85-foot Santrina as it lurched on turbulent seas.

Pujol, the ship's captain, struggled to keep the current from twisting the ship into the rough water as the wind blasted the crew with salty spray. Still, the crew paused for a nostalgic glance of Pinar Del Rio's mountains -- jagged teeth on Cuba's horizon barely 100 miles from Isla Mujeres.

The Santrina ran aground in shallow waters outside Isla Mujeres' port, attracting the attention of Mexican authorities, Pujol said. Once they got the boat free and at port, Pujol said Abascal told the group he was going to visit a girlfriend and left.

''[Abascal] said he was going to give me a picture of his friend in Isla Mujeres, but I never saw it,'' Pujol said.

In May, Alvarez told The Miami Herald he used the Santrina to travel to small foreign ports as a way to avoid being detained or questioned at international airports.

All the men say they did not take Posada back with them. It's not clear if they met with him at the Mexican port. ''I don't remember if Posada was there,'' Pujol said. Abascal said he did not see Posada in Isla Mujeres.

Alvarez, Pujol, Posada and the U.S. government maintain a coyote smuggled Posada across the Texas border days after the Santrina's trip.

Posada is now in detention in an immigration facility in El Paso, where a judge recently ruled he could not be deported to Cuba or Venezuela because he may face torture there, though he may be deported to a third country yet to be determined.

Venezuela wants the United States to extradite Posada to face trial for his alleged role in the bombing of a Cuban jetliner in 1976 that killed 73 people when it departed Barbados on the way to Jamaica. The accused plotters, including Posada, were all living in Venezuela.

After Posada's capture, FBI agents began interviewing the passengers of the Santrina and other friends of Alvarez.

Sometime during the summer, Abascal told Pujol the FBI had been questioning him and putting pressure on him, Pujol said.

The FBI also has questioned Pujol, he said.

A MISCALCULATION?

Pujol believes Alvarez made a mistake in granting a clandestine news conference for Posada in May, because it provoked the authorities.

''The correct thing would have been to take Posada directly to the CIA, not take him to the television,'' Pujol said.

Shortly after the news conference, which was held the day The Miami Herald published an exclusive interview with Posada, federal agents detained Posada at Lopez Castro's house, said Abreu and a witness who asked not to be named.

Posada's last Cuban meal as a free man consisted of congrí (a rice and beans dish) and ropa vieja (shredded steak in tomato sauce).