Hi Tomas, hi Frederik,
thanks for your kind comments an the info :-)

I found this on Wikipedia:
She was originally a Canadian River class frigate called HMCS Stormont and was launched in 1943. She served as a convoy escort during the Battle of the Atlantic and was present at the D-Day landings.[1] After the end of the Second World War she was one of many surplus naval vessels and Greek shipowner Aristotle Onassis purchased her for just $34,000. He spent $4 million to convert her into a luxurious yacht and renamed her Christina after his daughter. Finally in 1998 she was purchased by Greek shipowner John Paul Papanicolaou who had sailed on her as a child. He changed her name to Christina O and undertook a major refurbishment between January 1999 and April 2001. As of 2006 she is available to charter at between 45,000 and 65,000 Euros per day.

http://en.wikipedia.org/wiki/HMCS_Stormont_(K327)

Regards Frank