The girlfriend of Jim Clark, the 64 year-old founder of Netscape, has given her first interview about their relationship.

Australian Sports Illustrated model Kristy Hinze, 27, said that she was won over by the billionaire's charisma and intelligence.

"I never thought I was going to date an older man when I first met him," Hinze told The Australian Women's Weekly.

"To me, it was different to hang out with someone with something to say that was so interesting and important and who was truly, incredibly intelligent. He's handsome and has so much charisma - and he's so funny."

The two became close during Clark's third divorce, from former Forbes magazine reporter Nancy Rutter. They have since been spotted on Clark's yacht Athena, the largest privately-owned yacht in the world.

"He's very normal and down to earth," said Hinze. "He's an incredible man and I just love him."

Clark founded Silicon Graphics in 1982 and Netscape in 1994. His net worth is estimated at over $1bn.