@Cascabel: It didn't come together as an answer—and I got distracted by the truly bizarre side issue of how huzza became hurrah in U.S. English, with Noah Webster reportedly arguing in …

The OED has hooray as a variant of hurrah meaning goodbye, from 1898.Hurrah and hurray are a shout or cheers of encouragement, from huzza of 1573.

This takes place early in the morning, so she could be the rising sun. But sea shanties are work songs so it is more likely to refer to raising the very heavy main sail and the gaff (cross beam) …