From Alan James – 21 May 2020
I agree, it’s likely to be crò-sheangan. Both words can mean ‘a narrow place’, of cró DIL says ‘A term of very wide application, the basic meaning being enclosure, enclosed space, fold, pen, etc.’; while seangán is primarily just ‘a little narrow thing’, so ‘a creature with a thin waist’. I think here it’s just ‘tight place of (the) narrows’. The entrance to the eastern arm of Kirkandrews Bay is indeed narrow, I think the name is a warning to sailors that getting into here means navigating between a rock and a hard place!