What do you mean with in need of? To build, buy, charter or just collect information? There are not many around...
The only one I can think of is the 74.5 m Enigma, (ex Eco) which was sold last year to the present owners. Then you have Destriero, the speed record boat, which lacks yacht interior. Bigger than these are Ecstasea at 86 m, but as far as I know none of these are up for sale. But I can design one...
Try it with a cat The most sensible way to achieve the speed with that sort of length is with a cat. Anyone disagrees? With Lars I've been "working" on this kind of larger craft. With a monohull you'll need enoooooooormous power such as the turbine-installations on Eco or Ecstasea, and still it will not be an enjoyable ride!
I have one for you. Please send a private email to discuss. I hope you know that we will speak about 1 Million per meter. Alex
70m yacht Lars between us. Luca has one on his drawing board. So dont search the whole web it is an internal information. I will send you some infos when i am back from the Palma Boat Show next week.