An analysis of the ships captured by Somali pirates last year found that most of them had ignored recommended security measures, while passing through the Gulf of Aden, or elsewhere along the Somali coast. About a quarter of the merchant ships moving through this danger zone just take their chances. The odds aren't bad. About one in 500 ships passing through the area are captured by pirates. But closer to one in a hundred are attacked or threatened. The pirates have learned to seek out the unprepared merchant ships, knowing that these will be easier to get aboard and capture. Thus these ships that are just playing the percentages, have a higher risk (closer to one in 200) or being captured.
The precautions ships can take are costly, time consuming and an extra burden for the crew. The costly measures include moving through pirate infested waters at the highest possible speed. This can cost several thousand dollars more per hour. Ships are also advised to zig zag in pirate waters, that can cost you an extra few hundred dollars an hour, and demands more attention from the crew. Other preparations include stringing barbed wire around likely boarding points, and practicing the use of fire hoses and other tools (like long poles) to keep the ladders or grappling hooks from enabling the pirates to get aboard. Crews are also advised to prepare a "safe room" (an area of the ship the crew can barricade themselves in, if they have to, until help arrives.) There should be emergency communications available in the safe room, so that help can be summoned before the pirates figure out how to get in. The most common safe room solution is barricading the crew in the engine compartment.All these precautions take time and money. For ships that regularly travel past Somalia, the effort and expense are worth it. But for ships that pass by infrequently, there is a tendency to play the percentages.
For most of the past decade, the pirates preyed on foreign fishing boats and the small, sometimes sail powered, cargo boats the move close (within a hundred kilometers) of the shore. During that time, the pirates developed contacts with businessmen in the Persian Gulf who could be used to negotiate (for a percentage) much larger ransoms with insurance companies and shipping firms. The pirates also mastered the skills needed to put a grappling hook on the railing, 30-40 feet above the water, of a large ship. Doing this at night, and then scrambling aboard, is more dangerous if the ship has lookouts, who can alert sailors trained to deploy high pressure fire hoses against the borders. Thus the increased vulnerability of those ships that just take their chances.