So far I count four theories of the meaning of "blow" in the chantey:

1. Whistle in a voice tube on a ship
2. Strike a blow
3. Pipe hands down from aloft
4. Expel flatus as propulsion

Amazingly, no one over the years this thread has existed has theorized that it's a sexual term (Guest on 5/21/07 at 9:47 came close). Many chanteys had "dirty" verses, and I think we should add the theory that in Blow the Man Down, the B word refers to felatio. Horny sailors, nothing but other men around for months on end... Let's not be closed minded, here.

You know, if we really applied ourselves, I'm sure we could think up lots more theories. Don't hold back, 'Catters!

Jerry