The duck-boat trial came to a halt Tuesday, on the second day of testimony, after the judge in the federal case urged the two sides to try to settle.

The trial may resume as early as Wednesday if lawyers for the passengers on the duck and for the two companies that operated the vessels involved in the accident cannot reach an agreement.

At stake in the negotiations is whether the companies are at fault in the accident and, if so, how much they will have to pay the passengers and the families of two victims who filed suit.

On July 7, 2010, a tug operated by K-Sea Transportation Partners pushed a barge into a duck operated by Ride the Ducks. Passengers filed a civil suit against the two companies, claiming they are liable in the accident.

Robert Mongeluzzi, a lawyer for the families of Szabolcs Prem, 20, and Dora Schwendtner, 16, the two Hungarian tourists who drowned in the accident, said it was not unusual that U.S. District Judge Thomas O'Neill Jr. asked the parties to settle. O'Neill is trying the case, so there is no jury to be kept waiting while lawyers talk.

The suspension followed emotional testimony from Kevin Grace, a passenger on the duck.

Grace said the duck's captain, Gary Fox, had told passengers where life jackets were but never demonstrated how to put them on. Fox also never told his passengers to don the life vests after he stopped the boat as a precaution when smoke began pouring from the engine, he said..

The barge forced the duck and its 35 passengers underwater in the Delaware River.

Grace, who was visiting from Illinois, said he struggled to put a lifejacket on his daughter Ruby, 9, as the barge neared the duck.

"Under no circumstances was I going to let her die if I had anything to do with it," he said.

Once they were underwater, it was "sheer chaos, sheer panic," he said. "The river rose up and just swallowed us. The only thing I could do was just grab hold of her hair and hold on. It was like being in a washing machine, with strange objects and shoes and clothes and people in the water."

The parties are discussing possible settlement before U.S. District Judge John Padova. A 19th-century maritime law limits liability to the value of the boats — a total of $1.8 million in this case. Mongeluzzi argues that the limit should not apply because K-Sea and Ride the Ducks were negligent.

Lawyers for the two companies have countered that they are not at fault and that Matt Devlin, the first mate on the tug, was the only person responsible for the accident. A National Transportation Safety Board investigation found that Devlin was talking to family members on his cellphone before the accident rather than keeping lookout.

Devlin had just learned that his son had been deprived of oxygen for eight minutes during what was supposed to be routine surgery. The child turned out to be fine, but in a panic, Devlin "lost his faculties" and did not follow safe procedures, Wayne Meehan, a lawyer for K-Sea, said Monday.

If the sides do not settle, the next testimony will come from tug captain Ben Woods, who will be in the courtroom, and from Devlin, who will testify via video because he is serving a one-year sentence for involuntary manslaughter in the case.

During Tuesday's testimony, Prem's and Schwendtner's parents listened through headsets as one of their lawyers, Peter Ronai, interpreted what was said for them because they do not speak English.

"They are not concerned about money," Ronai said. "They want to know what happened, how their children died."

They had planned to return to Hungary after spending the day in court Wednesday.

On Monday, Mongeluzzi showed video of the accident that appeared to show Schwendtner tossing a life jacket to someone already in the water.

Through Ronai, Schwendtner's mother, Aniko, said Tuesday in an interview outside the courthouse that she was proud of her daughter but angry at Ride the Ducks and K-Sea.

"Now they can see what a special girl Dora was," Aniko Schwendtner said.

As she spoke, a duck vehicle, which operates on land and in the water, passed by on Sixth Street.

Contact staff writer Miriam Hill at 215-854-5520, or @miriamhill on Twitter.