Keelhauling was a form of punishment for sailors at sea. The sailor was tied to a rope looped beneath the vessel, thrown overboard, and then dragged under the keel and up
the other side.
Keelhauling was generally a
death sentence since it could take as long as three minutes, and perhaps longer, to walk the ropes
all the way back to the stern. Often the ropes caught and dragged on barnacles on the ship's hull: the barnacles ripped the victim's clothing and skin to shreds as he was dragged along.