From the Background:

The smell of sea salt and sweat is heavy in the dank under-decks as you sit awake, uneasy. While the captain considers himself above such superstition, the rest of the crew have not taken your presence on the voyage in the best of spirits. Talk of ill omen and bad luck has swirled like a haze through the cabins since the Blue Lady first left port.

While you and the captain agreed that such talk was mere silliness, recent events have made you wonder. First, there was the poor fellow who fell into the rigging. Then there was the night the helmsman woke the whole crew with screams of "Ghost!" And now, on the full moon of all evenings, an unnaturally fierce gale is pelting the ship with rain heavier than most of the crew has ever seen.

Unable to sleep, you make a cycle round the crew quarters. It's quiet, quieter than you've ever heard it on this voyage. Even Old Joe, the perpetually snoring first mate is silent. Something is wrong.