yarely briskly or smartly. Here the boatswain is instructing the sailors to move quickly or the ship will be pushed aground by the storm.
roarers noisy and unruly waves; here so called because they care little for royal rank.
boatswain the ship's petty officer, in charge of the deck crew, the rigging, anchors, boats, and so on.
drowning mark refers to a mole, located on the boatswain's face, the appearance of which was thought to portend a person's manner of death. In this case, the boatswain's mole appears to be the type that predicts a death by hanging.
merely [Obs.] absolutely; altogether; here, it means that they are completely cheated of their lives by drunkards.
