A second day of extensive air and sea searches for five missing Russian sailors has been unsuccessful, officials said today.
A further low-tide coastal search for the crew of the MV Swanland will take place until dusk as hopes of their survival fade, the Maritime and Coastguard Agency (MCA) said.
The cargo vessel sank in the Irish Sea after being hit by an "enormous wave" in the early hours of yesterday morning.
The missing crew were named as Captain Yury Shmelev, 44, Chief Engineer Gennadiy Meshkov, 52, Second Engineer Mikhail Starchevoy, 60, Able Seaman Sergey Kharchenko, 51, and ship's cook Able Seaman Oleg Andriets, 49.
Second officer Roman Savin, 26, and Able Seaman Vitaly Karpenko, 48, were airlifted to safety by an RAF helicopter co-piloted by the Duke of Cambridge.
Chief Officer Leonid Safonov, 50, was pronounced dead after his body was recovered from the sea shortly afterwards.
Holyhead Coastguard watch manager Ray Carson said: "Sadly we still have not been able to locate the missing seafarers.
"We will carry out one final search at low water today."
All eight members of the Swanland's company were Russian citizens.
Russia's ambassador to the UK Alexander Yakovenko sent a letter to Prince William which thanked the search and rescue teams for their efforts.
Mr Yakovenko said: "We know that you took an active part in the rescue and the two seamen were saved thanks to your selfless effort under the bad weather conditions.
"Let me express to you and your colleagues my deepest gratitude for saving the lives of the Russian citizens."
The Swanland sank about 10 miles west of the Lleyn peninsula in North Wales.
William's search and rescue team, based at RAF Valley on Anglesey, was called into action when the cargo ship issued a mayday call at around 2am when its hull cracked.
The Duke is understood to have been involved in the operation for several hours.
Earlier today, the Government announced that Britain's search and rescue (SAR) helicopter service is to become a civilian-only operation.
Transport Secretary Justine Greening said she expected to award a contract for work in early 2013.
The winning bidder would be expected to operate from 10 locations but provide at least the same level of SAR service as at present.