We do a group ride once a year to Cedar, near Nanaimo and take a ferry. There is a rack that holds a couple of bikes the rest just get leaned against the side of the ferry. I don't recall having to stack bikes but we may have. We all have decent road bikes and they're always unlocked with our sweaty helmets offering the only protection. I believe the ferries have security cameras that cover the bike storage areas. I've never heard of a theft although I suppose someone could take a bike and stuff it in a van.