First line of defense obviously is the crew who are really supposed to all be STCW certified which has a basic firefighting course or whatever the flagged vessel's countries version is but a kitchen or engine fire can get out of control pretty quickly,

As far as I know the only way to put out a boat fire (other than Bruce's waterline method) is with an actual fire boat that draws water from the sea but I don't think that even the USVI have one, last year the USCG had to tow this out of the harbor to let it burn http://www.fox5atlanta.com/news/108881473-story the firetrucks on land could not reach it even though it was so close to shore. I would imagine even a fire boat wouldn't be much help unless it was right in the vicinity.