A photographer who lost two of his closest relatives in Hong Kong's deadliest marine tragedy of recent times has vowed "never to forgive" the two skippers involved after a jury found them guilty in the deaths of 39 people on their way to a fireworks display in Victoria Harbour. After almost four days of deliberation a High Court jury returned to find Lai Sai-ming - captain of the Sea Smooth ferry which collided with another ferry that sank off Lamma Island on October 1, 2012 - guilty of 39 counts of manslaughter. Lai was also convicted of endangering the safety of others at sea. Chow Chi-wai, captain of Hongkong Electric's Lamma IV, was acquitted of manslaughter but found guilty of endangering the safety of others at sea. WATCH: Lamma ferry disaster - the deadliest boat accident in Hong Kong in 40 years Lai, who faces a maximum life term, sat in the dock with his eyes closed as the verdicts were announced, while Chow sat impassively as he was acquitted of manslaughter. They will be sentenced tomorrow by the presiding judge Mr Justice Brian Keith. The maximum penalty for manslaughter is life in prison. The endangering safety charge comes with a fine of HK$200,000 and a maximum prison term of four years. None of that mattered to Ryan Tsui Chi-shing, whose elder brother, Tsui Chi-wai, and 10-year-old niece, Tsui Hoi-ying, drowned in the crash. "Even if there was capital punishment in Hong Kong, it won't be enough," he said. "I won't show them any sympathy. It doesn't matter what punishment the court passes. This is Valentine's Day. "We should remember how many people were separated forever from their loved ones. I will never forgive them." Irene Cheng, who lost her son Thomas Koo Man-cheung, said: "To be honest, the rulings can't compensate for the loss of 39 lives." Chow's wife was in court but none of the relatives of those who died were present to hear the verdicts. Tsui said of Lai: "I'm so angry with him. He was reckless then fled the scene." He also questioned whether Lai was up to professional standard of a mariner, who should have ample understanding of collision regulations. Of Chow, Tsui said: "He may seem less culpable. But his slow and relaxed attitude caused the collision He could have taken much sooner actions to avert the crash." During the trial, Chow and Lai blamed each other for causing the collision. The prosecution team accused the two mariners of being "grossly negligent" in their navigation, which contributed to the deaths. Chow's legal team tried to establish before the jury that his continuous efforts to avert the collision were cancelled out by the Sea Smooth. Lai's lawyers argued that a missing watertight door could be the cause of the Lamma IV's rapid sinking. The pair's lawyers said that they had not decided whether to appeal. A Department of Justice spokesman said that it would study the verdicts before deciding further actions. Police and defence teams in Lamma ferry trial were in a race for experts Police were in a race with the legal teams of the two defendants in the Lamma ferry disaster trial as both sides sought to assemble shipping experts in a case packed with complex navigation issues, a police source revealed. Expert evidence featured heavily during the hearing, which lasted 60 days, as the specialists were asked to reconstruct the deadly Lamma ferry collision which claimed 39 lives on the night of National Day in 2012. Their expert testimony before the nine-member jury was considered invaluable given how survivors and witnesses could only share fragmented and imprecise accounts of what happened that tragic night. The maritime specialists used radar data and wreckage examination results to map out the routes of the two vessels and the angle of the impact upon collision. The prosecution called four experts - Captain John Third, Captain Cheung Hon-yee, forensic scientist Dr Cheng Yuk-ki and naval architect Anthony York. The two defence teams - for Lamma IV skipper Chow Chi-wai and Sea Smooth captain Lai Sai-ming - called Dr Rafal Goralski and Captain John Simpson, respectively. The source told the South China Morning Post that police were originally planning to invite Simpson as a prosecution expert, but Lai's employer Hong Kong and Kowloon Ferry beat them to it. "Hong Kong and Kowloon Ferry contacted Captain Simpson right after the collision. The ferry company beat us because it is in the same industry as the captain," the source said. "We called him on October 3, as October 2 was a public holiday, but he had already been engaged." Police, the source added, then turned to Third - who they contacted hours before a Commission of Inquiry, which was appointed by Chief Executive Leung Chun-ying, to look into the facts and circumstances leading to and surrounding the deadly collision. Veteran mariners Third and Simpson were both well-versed in collision investigation, the Court of First Instance had previously heard. York helped the inquiry into the Costa Concordia cruise ship disaster off Italy on January 13, 2012 that left 32 people dead when the liner ran aground. Goralski, meanwhile, was an ex-project consultant for the Nato military alliance. The source added that police avoided those experts who were criticised by judges in other trials.