"Boulavouge" is quite recent. It was written around the time of the centenary of the 1798 rebellion - and was originally sung to a different air. As far as I recall, someone sang it to the current air at a Feis Ceoil (Irish music festival/competition) in the early 20C. - and the rest is history, so to speak! Throughout the 19C. the air was known as "Youghal Harbour" and was adapted to many songs e.g. Sweet Omagh Town.

Regards

p.s. For all that, Galway Shawl always sounds closer to The Ould Triangle than to Boulavogue to me.