The coxswain of the sunken Lamma IV said he made a full starboard turn when he saw the Sea Smooth ferry approaching a minute before the vessels collided, a commission of inquiry into the National Day tragedy heard.

But the radar record shows the vessel turned just five degrees. Thirty-nine people died in the disaster on October 1.

Chow Chi-wai also said he first saw Sea Smooth on the radar, but the public ferry's lawyer suggested Chow had "invented" the story for the inquiry, as it contradicted his previous statements to the Marine Department.

Chow told the inquiry yesterday morning that he had seen Sea Smooth on the radar, about one minute before the collision, then visually saw it "dead ahead". He said he immediately took action by making a full starboard (right) turn. He then switched off the engine to minimise impact when he recognised it was too late.

But Charles Sussex SC, for the owner and crew of Sea Smooth, noted in the afternoon session that the radar record showed Lamma IV shifted course by only five degrees in the minute before the crash. "The gradual change of course to starboard … was a navigational manoeuvre, and was not a collision avoidance manoeuvre," he said.

Chow insisted he made the turn to avoid collision, but said the Lamma IV - which was taking over 100 Hongkong Electric employees and their families to watch the National Day fireworks - could have turned slowly.

"You didn't even see Sea Smooth until a very few seconds before collision," Sussex said. But Chow rejected his claim, saying Sea Smooth was three cables (555 metres) away when he saw it.

Sussex also noted Chow had earlier told the Marine Department he did not keep an eye on the radar after he left the typhoon shelter. He also did not mention to police that he had looked at the radar. "I suggest to you that the story that you're now telling of seeing Sea Smooth on the radar is something which you have invented today," Sussex said. Chow denied the suggestion, saying he had simply forgotten to mention the radar in his previous statements. But he later said it was "more or less so" when Sussex suggested that he only applied full helm to starboard 30 seconds before collision.

Chow also said in a written statement that both vessels should have turned to starboard, according to anti-collision rules, and it was hard to understand why Sea Smooth did not.

Chow, who was seriously injured, was the last person rescued from Lamma IV.

The hearing continues today.