I have written in the past about the old Ulster-Scots and Scots word crack and the newer Gaelicised spelling of craic. Frank McNally, writing in The Irishman's Diary in the Irish Times today, about the singer Christy Moore referred to:
a career stretching back so far that, when he first sang The Crack Was Ninety in the Isle of Man, 'crack' was still spelt with a K
This is a reference to the Barney Rush song, which goes back to the 1960s and was recorded by Christy Moore in 1978. The traditional spelling was also used by author Jennifer Johnston in 1977 and by Brian Friel in 1980.
The Gaelicised version can be traced back as far as 1968 in Connacht and to an RTE Irish-language chatshow, which ran from 1976 to 1982. Around this time it also began to appear in English publications, borrowed over from Irish. But why use a borrowed spelling when there is a well-established spelling already there. The Irish version was simply the result of borrowing the word into a language without the letter K. There is a K in English and in Scots, so why not use it? There is nothing peculiarly Irish about crack and Ulsterfolk have enjoyed good crack for many a long year.
Diarmaid O Muirithe once said about this, 'The constant Gaelicisation of the good old English-Scottish dialect word crack as craic sets my teeth on edge.' Well said Dairmaid!