My best guess: There's a tune called "The Boatman" in Michael Raven's '1000 English Country Dance Tunes'.
Also, there's the Scots "The Boatman = The Bonny Boatman = The Bonny Scot", but this is a song tune. [See Scots tune index on my website for early sources]
There's a "Bonny Boatman" in an English MS of c 1625, and I copied it, but haven't figured out the notation. [Are solid ovals with no stems half notes or whole notes? Timing doesn't work out right for either.]