Drydock workers examined the underside of an 82-foot sailboat early Tuesday, evolving damage cause when three alleged boat thieves ran it aground off a Pacifica beach.

There was noticeable damage to the boat’s 10-foot keel as it sat out of the water at a Richmond drydock.

Three people were arrested Monday after they stocked the stolen sailboat with pizza and beer and sailed it out of its mooring in Sausalito. Hours later, the alleged thieves had sailed the boat under the Golden Gate Bridge and then ran aground in shallow water off Pacifica’s Linda Mar Beach.

Pacifica police arrested Leslie Gardner, 63, Dario Mira, 54, and Lisa Modawell, 56, on suspicion of grand theft and conspiracy. They were being held in the San Mateo County Jail. The strange tale began early Monday when beachgoers phoned police to report the sailboat in trouble.

The luxury yacht was trapped on a sandbar in shallow water at low tide and unable to get back out to sea. A few wetsuit-clad surfers had paddled out in the frigid water near the grounded vessel as its hull was battered by 4- to 5-foot waves.

After television news reports of the grounding aired, the boat's owner called police to report it stolen, Sausalito police Sgt. Bill Fraass said.

"We do have thefts of vessels throughout the area, but the theft of a vessel of this size is uncommon," Fraass said.

Authorities made brief contact with the three people on board, but the people refused to disembark at first.

Once officers were alerted that it was a stolen vessel, police surrounded it with guns drawn. After a few hours, the trio agreed to be taken off of the yacht, jumping onto personal watercraft and being quickly ferried to shore.

The boat's owner was called out to work with authorities to have it removed from the beach.