aussie owned motor yachts

As a beginner to this world of mega yachts i am just starting to get an understanding of how many of these floating palaces their are in the world. i am hoping some of yacht guys and girls can help me with this question: how many and which yachts are owned by Australian's.
Arctic P = Kerry Packer
Aussie Rules = Greg Norman
Ilona = Frank Lowy
I know there is alot more for example i beleive Mick Doohan the best bike racer in the world owns a 55m yacht but not sure of its name and i beleive his mechanical geniuse Jeromy Burgess also has one.
Can any one help me with this one..........??