two 21-year-olds and a 25 and 22-year-old collapsed on the vessel on good friday .
they were rushed to st vincent 's hospital in a critical condition but are now stable .
on friday afternoon , about 800 partygoers poured off the bella vista boat after the party came to an end .
the boat , which was hosting a ` dirty funken beats ' party , left king street wharf at noon .
police say they discovered cocaine , marijuana and mdma before the boat left the wharf .