The first half of the poem takes place on a ship and explores some of the beliefs that are intrinsic to this kind of life. Sailing life, particularly prior to the 20th century, was heavy with superstition and near-religious beliefs. Because the sea is so vast and unknowable (even today, but especially in times gone by), it was easy to imagine a pantheon of “rules” to follow to earn its favor. It’s because these beliefs are so ingrained that no one comes to the speaker’s aid when she’s betrayed.