The only lasting solution is establishing effective civil government over the pirates' land base. From Caesar onwards, that was how piracy was terminated. We are currently paying the price for the failed 1992-'93 international intervention in Somalia and for our reluctance to return.
Without success on land, history shows that piracy can only be suppressed, not ended, and only in two ways. Those do not include warship patrols. Pirate craft are smaller. cheaper, more numerous and more easily concealed than ships sent to hunt them — making patrolling a losing proposition. Aircraft could change the game but they have limited ability to distinguish a pirate from a legitimate vessel.
The two viable at-sea solutions are mercantile convoys with warship escorts and the arming of merchant ships, each of which has a long and successful record. The cost of delaying the traffic through Suez while ships are assembled into convoys would be enormous. It may have to be borne nonetheless.
Until the temporary end of large-scale piracy in the mid-19th Century, it was normal for large merchant ships to be armed, while their seamen (who often had warship experience) were trained in the use of "great guns". All that changed with the evolution of specialized warships, distinct from mercantile shipping.
Arming merchant ships today would not be difficult: A few heavy automatic weapons mounted on sponsons, allowing interlocking fields of fire around the ship, could easily be fitted. Providing trained gun crews, paying them and integrating them into the ship's command structure would be harder but possible. The pirates could not match such escalation in firepower without adopting larger, specialized vessels that would then be vulnerable to a patrolling frigate.
The difficulty would be institutional. Few today would willingly accept that a mercantile crew should open fire with heavy weaponry, on the command of a civilian captain, at any small boat coming within range — firing first and not stopping to ask questions after. It would be hard for a captain to give the order. Yet that may be what is needed to suppress piracy, until we are willing to send troops to restore effective government in Somalia.
Trevor Kenchington is a marine fisheries scientist with an avocational interest in maritime history and archaeology.