The Shadow Cat design by an england based design company is 58 Meter long and is based on a 80 Meter concept for the U.S. Navy and should have a speed of 30 knots.
The Shadow Cat can transport three 15 Meter tenders, severally cars, a submarine and a lot of Jet skis. On the Sundeck can tranported an Helicopter. (Or whatever

).
In my Opinion: