I've lost count on the number of 'boat songs' passed over to date; Fhir a Bhata / Fear a Bhata / The boatman was one of many.

However, Logan's The Scottish Gaël has come up again and the author does label the two lines of Fhír a Bhata's music as an iorram. Also, at least one later source (Peacock) links it to Fulling songs.