Piracy is the act of stealing, transporting, and selling stolen cargo from a trader's ship to a port in order to gain doubloons.
How to Pirate
Finding Traders to Pirate
When searching for ships with cargo to steal, you can hover over an enemy faction's ship with your spyglass to see how much cargo the ship has in its hull. Trading ships generally stop at notable trading ports such as Nassau, Whitecrest, Nova Balreska, and Harrisburg to sell and replenish their cargo.
Once you have found a ship to steal from, your next step is catching it. Trading Ships (such as the Camel, Mule, and Mastiff) are generally slow, and bulky and can easily be caught up with by faster, more agile ships (such as the Marauder, Pheasant, and Corsair). Cargo can then be stolen by hopping on a ship, finding its cargo hold, standing near it, and clicking "Steal" on the cargo hold's GUI. Cargo can then be placed back on your ship by dropping it with the "F" key or with the "drop cargo" GUI button for mobile players. Dropping cargo in water will result in the cargo going back into the trader's ship, and do note that you cannot steal cargo from a trader docked at a port.
Transporting Stolen Cargo
Just like regular cargo, stolen cargo has to be transported to an island other than the cargo's island of origin. The further away the destination island is from the cargo’s origin, the higher the sale price and experience gain (experience is proportional to the amount of profit). Where the cargo was stolen doesn't matter, only where the cargo is from(which can be determined by the type of cargo).
Just like regular Cargo, stolen Cargo can be sold by interacting with an island's trader (all named islands excluding Clydesdale and Saint Christopher have traders), selecting the type of Cargo, and clicking "Sell."
Stolen cargo will sell for 2.5x of the cargo's regular selling price, with the base sell price dependent on the distance between the cargo's origin and where it is being sold at as well as the island's demand.
When you are in a crew, all crew members will get doubloons as well as experience from sold cargo, but the revenue and experience are reduced slightly for crew members compared to the captain. Having a crew with a number of members greater than an amount relative to the ship's cargo hold will cause the crew to earn fewer doubloons from sold cargo.