In a brief preliminary report on the July 7 collision of a tug-driven barge and a duck boat that killed two young tourists, the National Transportation Safety Board said Friday that the tug's pilot evidently did not respond to the radio distress calls of the stalled duck and other nearby vessels.

However, the two-page report is not a finding of fault and is only a "summary of factual information" about the incident, an NTSB spokesman said.

According to the board's chronology of the accident, the duck entered the water about 2:15 p.m., with 35 passengers and two crew members. About 10 minutes later, its captain detected smoke from the engine compartment. He turned off the engine and called on VHF marine radio channel 13 "to alert other vessels in the vicinity that [it] had broken down and lost propulsion."

The captain then ordered his deckhand to anchor in the river to keep from drifting, and called his company for a tow.

A recording of radio calls made by the Burlington County Bridge Commission, operator of the Tacony-Palmyra Bridge about seven miles north, revealed that nine minutes later, at 2:36 p.m., "a person can be heard calling out to the northbound tug (the Caribbean Sea) near Penn's Landing saying that he is DUKW34, is broken down and cannot maneuver," the NTSB reported.

"Over the next minute he made several additional callouts to the northbound tug," as did others who saw it approaching at about 6 m.p.h. "No response from the northbound Caribbean Sea can be heard on the recording."

Attorney Frank Desimone, who represents the unnamed first mate who was steering the tug, called the report a "rehash" of what was known about the accident. He declined further comment.

His client has refused to testify before federal investigators about his actions before the accident.

The president of Ride the Ducks Unlimited, the tour boat operator, noted that the NTSB found the duck captain "took expected precautionary measures."

"It unequivocally shows our captain's repeated distress calls on the established broadcast channel went unanswered [by the tug] although they were heard and retransmitted by other vessels in the area," said Chris Herschend, head of Ride the Ducks.

He added, "The question remains, why did these calls go unanswered, and why won't the first mate cooperate in the investigation?"

The NTSB report noted that alcohol and drug tests of the crews of both the tug and the duck boat were negative.

Robert Mongeluzzi, a lawyer for the families of the two Hungarians who died in the accident, said the report did not absolve the duck operator.

"The duck boat decided to shut engines down in the middle of a shipping channel," Mongeluzzi said.

Nevertheless, he said, "the only possible explanation" for the tug's not responding to the duck's distress call "is that they turned their radio down or off."

Mongeluzzi said he intended to argue in civil suits that Ride the Ducks and the tug's owner, K-Sea Transportation, "shared responsibility" for the collision.

A detailed analysis of the accident, along with recommendations on how to prevent collisions, is not likely until next year, said Ted Lopatkiewisz, an NTSB spokesman. He declined to comment on the report, as he said was standard policy at this stage in the investigation.

Managing Director Richard Negrin said he was disappointed that the report gave no new information, but said it was of some value because it provided a "third-party investigation of the facts."

City officials will meet with Ride the Ducks and other parties to discuss whether the vehicles should be allowed to return to operation and whether there should be changes in how or where they travel.

The vehicles, which can carry 40 passengers and a crew of two, began operation here in 2003. Until voluntarily suspending operations after the accident, they typically traveled city streets for about 45 minutes past popular tourist sites, then splashed into the Delaware for a 15-minute cruise around Penn's Landing.

Negrin said the city had been considering requiring the vehicles to cruise the Schuylkill instead of the busy Delaware, but finding a suitable route in the river is proving a challenge.

Contact staff writer David O'Reilly at 215-854-5723 or doreilly@phillynews.com.