I read the following paragraph in Radriano's thread celebrating his new CD:

The second verse contains the line "with a bone in her mouth, boys" which I first took as a very explicit sexual reference. In a house concert performance by Dave Webber and Anni Fentiman two years ago in Berkeley, California Dave sang the same line in another song. I asked him about it during a break and he said that the line refers to one of the sails (he called it the "water sail") which is slung quite low in the front of a ship. If you are looking at a ship head on when that sail is up it looks like the figurehead is holding something in her mouth. The phrase "with a bone in her mouth, boys" became a specific reference to heading southward with all sails up - the beginning of a voyage.

My understanding of the phrase "a bone in her mouth" (also frequently seen as "a bone in her teeth") is that it refers to a ship with white water foaming at the bow. A good example of this is a line from one of C.F. Smith's poems which describes a ship with a lot of speed on her as having "a wake like a mill-race and a bone in her teeth."

Never thought of the sexual connotations of this.

BTW, the "water sail" mentioned above is, I think, what was called a spritsail, since its yard was crossed on the underside of the bowsprit. From what I've read it was a common feature of sailing ships up until the early 19th century, when ship designs changed and it went out of vogue.

Jerry