the collection is generally inferior to that at Keills, but this pair are rather different. The rowing galley at the top must have been closely related to the invading Norse ones, but were used very effectively by Somerled to achieve a status of "Lord of the Isles" in the C12th independent of both Norse and Scottish contenders. These stones are assumed to be associated with this ephemeral ascendancy
http://www.bbc.co.uk/scotland/history/articles/lords_of_the_isles/ Nigel Tranter gives a readable if possibly romanticised history