Keelhauling was a punishment method many sailors were forced to undergo, but few lived through. Often associated with pirates, keelhauling was actually a more common practice on British Royal Navy ships. The earliest example can be found in artwork from ancient Greek and Rhodian naval cultures, circa the ninth century BCE. In the 17th century, the Dutch government adopted keelhauling as a punishment for wayward sailors.
This method was famously depicted in a Dutch painting from the late 1600s - in The Keelhauling of the Ship's Surgeon of Admiral Jan van Nes, Lieve Verschuier illustrates a doomed surgeon dangling in front of a gawking crowd. While keelhauling is a horrific punishment by today's standards, such events were often considered entertainment at the time. Although the practice was banned in the mid-18th century, the term is still used to signify severe scolding or excessive punishment.
Since the captain of a vessel was considered the lawmaker, keelhauling was not attached to a concrete set of offenses - the punishment was meted out at the leader's fancy. Due to its brutal nature, keelhauling was typically reserved for the most serious crimes.
Contrary to popular belief, keelhauling was not as prevalent on pirate ships as much as it was on Dutch, French, and British naval ships.
The offender was bound in a way that would prevent him from escaping and swimming to freedom. A cannonball or chunk of ballast was fastened to his legs. This weight allowed the sailor to sink just enough to reach the underside of the ship, also known as the keel.
Usually, after a sailor was prepped, crew members ran one rope from his back to the main part of the mast and another from his feet through the block on the side of the ship. The rope went underneath the vessel and back up the opposite side. The crew then guided the sailor overboard until the captain gave the word to drop him into the water.
A French version of keelhauling featured two ropes run through blocks located on each side of the ship and then tied to a small hatchway grating. The sailor was then lashed to the grating like a makeshift gurney, with weights attached to the grate instead of the sailor.
The crew lowered the sailor into the ocean at the signal of a gunshot, the firing of a cannon, or direct orders from the captain. Just the shock of hitting the water so violently could cause internal injuries.
At this point, the crew ran the aft line as quickly as possible to pull the sailor under the keel and back up the other side of the ship.