The ship, called the Al Messilah, has 52 crew on board.
Almost a dozen other people who had close contact with the crew are likewise in quarantine tonight.
The numbers will be counted as part of WA’s official figures tomorrow. Today, the state reported no new cases of coronavirus.
But fears of a new outbreak have again delayed a further loosening of lockdown restrictions.
Phase Five had been due to come into force on Sunday.
But now, the two-square-metre rule will remain in place for most venues.
However, from Saturday, some ticketed venues will be able to operate at a 60 per cent capacity.
And from Sunday, the two-square-metre rule will be removed for theatres, concert halls, cinemas, auditoriums, comedy lounges and performing arts centres.
