I see that the Boar is holding a deer bone in its mouth as well, which might be a linguistic association with the name MacKinnon, some reference to its earliest reference in this "Book of Deer"????:

"MACKINNON, MacFhionghuin ,MacFhionnghain or McFionguine.
The old Gaelic personal name occurs in the Book of Deer in the genitive as Finguni." http://www.turningwood.fsnet.co.uk/clanmackinnon.html

As hypothesized, supposedly the castle referenced is here:
"The castle, properly called Dun Haakon, was a broch (a circular dry-stone tower) commanding the narrow sound between Skye and the mainland." (same site, castle totem)

And here is the reference to the old abbey lands of Iona, so that makes sense too, as you said:
"The Mackinnons were closely connected with the abbacy of Iona, Like the other Alpin branch MacFie, they had at least a interest in the holy Isle of Iona, where several MacFingons or MacKinnons were abbots. " (same site, this would go along with the hand-and-cross)

Still think the Galley is as above.

K=