So some updates-
There are now 5 cases on the ship. All from the same party.
And my speculation seems pretty close- the original person was tested 72 hours prior to boarding. And then had symptoms quickly- well within the margin of time of incubation between the test and getting sick. Boarding was Saturday (so testing was Wed?) and the first positive test was Tuesday.
So the procedure should be just like pro sports- quick and immediate before boarding. Otherwise, given the required travel to cruise, you are playing with fire.
edit- now 7. And apparently if you have tested negative, you can fly home tomorrow. hmm... given that masks were not required until someone actually tested positive after showing symptoms, I'm not sure about that.
edit 2- reading through some more of a thread on cruise critic- it's quite safe to say that many of the passengers are selfish and stupid. They protested the fact that the ship required them to wear masks after an outbreak happened- as if they could get away with not wearing one. And the ship is letting people outside at specific times to prevent people from gathering- naturally, the few people outside are gathering w/o masks.
Wow, these people are both dumb and in denial- given they flew in the middle of a major uptick in cases.