The Iron Bottom Hunters are a progressively more armored hull naval ship of Umbak. It is a product of the Automata Brigade of Virtue and Reason. These were made to hunt war ships in ancient times. They were large and heavy, not useful for anything except war. They were meant to survive a battering ram strike or the rocks off a coast. They almost never sank, and when they did it was rapid, dooming most of the crew. They are prohibitively expensive to build and have assistance propelling them from mystical means. They are few in number now, being expensive to maintain.
The first made, the “Silver Eventide”, has the distinction of slaying the crew of The Greentooth at the end of the Dread of Vesicant.