Here's a video of pretty impressive performance of a powercat in some nasty conditions. It's a Wildcat 36 built in Ireland http://www.youtube.com/watch?v=Vuemirsn6LY http://safehavenmarine.com/contents%202%20nd%20version.htm
Strangely, just this morning one of our 1st year apprentice engineers was trying to find this vid for me to watch but could not remember the title. There are 2 Interceptor chartboats over here, and yes they do go out in all weather. Very tough bits of kit.
Can't say the seas were exceptionally bad, but they took them from every imaginable angle and did it well. I took special note to when he was coming in the inlet and took the quartering sea. The boat started to go for broach and straightened out as soon as the second hull caught. Even broadside to the waves there was no big roll. Have to love cats in rough water. I did note however that they were using the lower station. Guess I'm not the only one who hates being up on a flybridge in that stuff.