A yacht was seen from the 37,500-ton Pride of Bilbao ferry
Three independent sources proved that a missing yacht had a near miss or collision with a car ferry in the Channel, a court has heard.
The jury in the trial of Michael Hubble was told the Ouzo was near the 37,500 tonne P&O car ferry Pride of Bilbao.
The 25-foot yacht disappeared in August last year and her crew of three men, from London and Kent, drowned.
Mr Hubble, 62, who denies manslaughter through gross negligence, is being tried at Winchester Crown Court.
He has also denied engaging in conduct likely to cause death or serious injury.
James Meaby and Rupert Saunders, both 36 and from Tooting, south London, and Jason Downer, 35, from Kent, all drowned after their boat was lost.
Yacht location tracked
Mr Hubble of Capel-le-Ferne, Folkestone, Kent, was officer of the watch on the ferry when it is alleged the incident with the Ouzo occurred with the ferry either swamping or colliding with the yacht.
Mr Hubble, a seaman with 40 years' experience, told police that he saw a yacht pass close in the early hours of 21 August as the ferry was en route to Bilbao but he spotted its lights astern as the ferry passed and he did not think there was a problem.
He did not accept that the yacht involved was the Ouzo, the court heard.
The jury at Winchester Crown Court was told by prosecutor Christopher Parker QC it was possible to track the progress of the Ouzo after it left Bembridge on the Isle of Wight on the evening tide of 20 August and headed south and then west for its destination of Dartmouth Regatta in Devon.
Left to right - Jason Downer, Rupert Saunders and James Meaby all died
The barrister said the mobile phones of the three friends could be followed as they pinged to and from phone masts on the island, and it was possible to track the yacht from a shore-based radar.
Calculations using tides and sea conditions back-tracked from the spot the bodies were found also gave the same location where the men entered the water.
"We say that these three independent sources of information strongly suggest that this yacht was indeed Ouzo," Mr Parker told the jury.
The two came close to each other at 1.07am on 21 August according to the ship's "black box" recorder, the court heard.
Mr Hubble was on the ferry's bridge and manoeuvred the ship to avoid a yacht.
Mr Parker said that the officer should have stopped the ship, called the captain, radioed the yacht to check the crew was safe and alerted the coastguard.
However, he did nothing, leaving the three men swimming in the sea in the wake of the ferry as it sailed on, Mr Parker said.
"He owed all three yachtsmen a duty to take action and steps necessary to protect then from death or serious injury. He owed that duty as a fellow mariner," he said.
Mr Parker told the jury that Mr Hubble was not "wicked or malicious" but he had been "grossly irresponsible" and he made "a terrible mistake".