US Navy Assisting With Anti-Piracy Efforts In Gulf Of Aden

Using firehoses to repel boarders, among other tactics.

I don't know what sort of firehoses merchant ships carry, but US Navy ships have hoses with heavy brass nozzles that can be set for either a "fog" effect or a "straight stream." Normal firefighting technique calls for the hose to be set for "fog" much of the time, but "straight stream" would result in a high-pressure blast of salt water that would make a formidible deterrant. In fact, the "straight stream" firehose setting is used in Navy hazing ceremonies such as the initiation for crossing the Equator: typically the unitiated, called pollywogs or just wogs, are bathed in a vat of kitchen garbage (the "royal bath"), then blasted across the non-skid deck with firehoses set to "straight stream" (the "royal shower). This results in the wogs being abraded by the non-skid surface, which, combined with the salt water from the firehoses, makes for some discomfort for a day or so.

Anyway, a firehose set to "straight stream" could easily knock a pirate off a ladder and prevent him from boarding a ship. It could even result in injury if the hose-wielder manages to hit the pirate in a sensitive spot, e.g., the goolies.