Keel hauling involved tying a sailor to a rope and passing the rope from one side of the boat to the other, under the keel. The rope would then be pulled, so the saior was dragged over the side, under the boat, and up the other side. This was a serious punishment - the poor man would be almost flayed alive by scraping on the barnacles that infefsted all ships' hulls, and if the crew pulling the rope were not fast enough, he would drown. For particularly heinous crimes, the hauling could be done for the length of the boat, rather than the breadth, which virtually ensured that the man would drown before he surfaced - more of an example than a punishment. Any sailor surviving the razor-sharp barnacles shredding his skin, and the instant salt-water bath his wounds received, would think twice about transgressing again.