They are FB MIL-50's (Fabio Buzzi Design).
They are powered by 3 x 1000hp Seatek engines giving a topspeed of "over 70".
They have Trimax Surface Drive props with 2-speed gearboxes and, undeneath the boat, are FB Design built-in trim tabs.
The hulls are composite Kevlar, foam filled, making the external hull surface impregnable to marine growth.
These boats are in use by the Royal Marines and one of them developed an engine fault and they had to call in at Alderney for repairs.
A couple more piccies.