I forgot to mention - in this case the "harvest" did not refer to crops, but to the menhaden fish, which were caught using heavy nets which would be dragged up between lines. The "Steamboat" was the fishing boat, not a paddleboat. Once you understand these two things, the song makes a lot more sense.

The other thing I note about this song as sung by the Bright Lights Quartette is that "Rose Anna" might refer not to a lover but to a child. To me this makes it all the sweeter.

Dan