The phrase "swift boat" describes a Vietnam-era patrol boat, but it is increasingly being used to describe the political tactic of using a concentrated media effort to discredit a person or idea.
The phrase developed out of the 2004 U.S. presidential election, when a group called "Swift Boat Veterans for Truth" attempted to suggest that Democratic candidate John Kerry lied in order to earn two Purple Hearts and a Bronze Star during the Vietnam War. The group, as it turns out, was funded primarily by people who also frequently donated millions of dollars to the Republican party. Swift Boat Veterans for Truth was formed for the sole purpose of discrediting Kerry's Vietnam War service and has not been heard from since the end of the election.
From Wired magazine: "Phrases like 'junk science' and 'sound science' are creations of the right in its effort to 'swift boat' research it doesn't like."