The French link is not working. I can confirm that the yacht is called ‘Sigma’ or ‘Project Sigma’. It is 387 feet long. It may belong to Roman or Malenchenko (who?).

Name correction, the yacht may belong to Andrei Melnichenko and Roman is a client of Andrei’s.

http://www.forbes.com/lists/2006/10/H6VQ.html