The RNLI rib in the picture is a serious bit of kit. It's an E-Class, 9m long. It's got Foam sponsons, and has an open stern, with twin Jet Drive engines made by Steyr. The one near me in Gravesend has twin 240hp engines (aluminium) giving it a top speed of 41kts, with limited loss of performance in heavy weather.
Apparently the designers say the hull will not go faster than 41kts, but someone at the station reckons that by fitting twin 350hp jet drives, they "might" get 45-48kts out of it, so they're going to try it! They're constrained by having to be on the scene of a shout in under 15mins for shouts on their patch, so need something as fast as they can get, carrying all their safety kit, and being able to perform in heavy weather.
I was lucky enough to get a spin in one of the E-Classes in the early days before the RNLI overhauled them, and with the buckets controlling the jet engines, from 40 knots they can stop the rib in about 2 boat lengths by reversing the buckets. Turning was also pretty impressive, and the helms can make the rib go sideways!
All in all a very cool rib with a fair amount of power behind it!