I have observed many times the syndrome "because it has been around since before we were born it has always been around". Witness the allegation that the Bodhran existed as a word before 1950. The earliest reference in print in Ireland is around 1900 and I am informed by a scholar (who can be wrong but is unlikely to be) that the Gaelic dictionary it appears in is mostly a list and there is no description attached to that word. But there are folkies purporting to be erudite and tell you you are wrong. Even within this parish.

Having said that - I find it impossible to believe that steering a boat for miles along flat terrain or trying to get bairns to sleep cannot involve singing for many boaters. And given the nature of creative people (who exist everywhere in large numbers) - that they would not personalise songs they knew - or wove new ones. The real problem is documentation or lack of it. The oral tradition only becomes noticeable with cross-polinisation and boaters were hard working and a close nit community.

There was a tradition that survived the demise of the industry - their paintings.