It's worth checking the Caledonian MacBrayne website updates for service disruptions. This seems to be the company that covers most of the major routes. There's usually something wrong with them.
They may be doing better now, but a few years ago they had a habit of running their ships aground on particularly sharp and pointy rocks, which didn't do much for service reliability. I've no idea if this is true, but an acquaintance in Aberdeen opined in a broad Scots accent that they employed skippers who couldn't get jobs elsewhere on account of their poor accident record.
