In the transition from the UK to America The Boat that Rocked got a new title and a slightly different poster. I guess they thought the original just wasn’t zany and fun enough, so we get more people walking the plank (including a girl!), a second, more party-centric boat, and some stuff in the title. Oh yeah, and curiously enough a different angle of the main boat.
I like the cleaner UK poster better, from a purely aesthetic perspective, but I understand what they are trying to do with the American one. I’m not sure they haven’t gone too much into Animal House territory but I understand. And it must be said that new title fits the poster’s concept much better.