Well, isn't this disturbing.
It sounds from the story like it was more a case of an mischievous idiot with too much time and access to explosives on his hands, but it brings to the forefront a disturbing possibility: there is no practical security on BC Ferries to stop anything much, much worse. (This story took place on one of the ferries from Washington, but I've travelled on the ferries many times and this situation could easily occur - the only reason this bomb was caught was because the man had to go through customs.) I think BC Ferries would do well to look at ways to improve security.
Obviously, there are limits to what you can do to guard against terrorist attacks. However, given the extreme difference between what you go through to get on a plane with a few hundred other people, and what you go through to get on a ferry with a few hundred other people, some improvements could be made to make ferries a less attractive possibility for terrorists. It could be as simple as having security guards with bomb-sniffing dogs pacing the aisles with the paperboys. I'm sure people better-versed in security procedures than I could think of many more easily-implemented ideas.