Thanks for your query.
30 is not the emergency contraceptive
YOu can go ahead and take a risk, by taking two tablets at once, and then two tablets 12 hours later.
however, i repeat, this is not advisable and not guaranteed of protecting against pregnancy
Also, it should ideally be used as a regular contraceptive.
Wait for your period to begin, and start using a fresh pack from the 1st or 2nd day of your cycle, if you intend to use it as a regular contraceptive.
Please consult the gynecologist / physician on board the ship for detailed prescription and guidance.