The lead character got seriously injured in the movie, and me wonders what happened. I am thinking it might the bad guys in the 'big' ship, but that is just a guess, since there was no mention of it later on... even in court.
Yeah, its the guys on the boat. They were so rough that the other prostitutes would not go there, and tried to brutalize Bess on her first visit there. She goes back and the next thing we know she is heading to the hospital in serious condition.
Its not explicitly shown but I think that is just because they were trying to avoid being gratuitous, I personally didn't see where there was any ambiguity as to where her injuries came from.