That's the one, if you mean a ship that was actually a bomb and not a mortar carrying vessel. Hellburner was the actual term I was looking for. The Dutch first used them in action against the Spanish at the Siege of Antwerp (1584-1585) during the Eighties Year War. The Spanish feared them so much that when fireships (not hellburners) were set against their Armada by the English that they really ran for it. The Dutch developer of the Hellburner ship was known by the Spanish to be in England at the time so their fear of them wasn't unfounded.
Here is a link to a pretty good entry in Wikipedia about them:
http://en.wikipedia.org/wiki/Hellburners
OK Felix, your turn again.