Saw these bad boys recently (photos from Internet) . This is the US Special Boat Team 11 metre Rib, 36 ft long, 11 ft beam, only 0.9 metre draft. It has twin Caterpillar 3126B Marine engines, producing a total of 940hp driving Rolls Royce Jet Drives. Costs over 700,000 US dollars and is used by Special Warcraft Combatant-craft Crewmen (SWCC), for covert ops, insertion & extraction of US Navy Seals from hostile environments. When leaving the combat zone a Military Helicopter flies low, they clip onto cables and they fly off with the Rib and crew. Now that's a scary ride! Capable of 40 knots plus, this is an awesome beast!
Being an ex Caterpillar mechanic myself, I was very interested indeed. They sound awesome and look terrifying!