@Cazatou,
We could always bring back "Q" Ships.
There might be a number of legality issues with Q ships. Now don't quote me as I may be wrong; in fact I just looked up the relevant articles from
here:-
Under the United Nations Convention on The Law of The Sea, all warships, when sailing in neutral or international waters must be identified as such.
Article 107 states that seizure on account of piracy may be carried out only by warships or military aircraft, or other ships or aircraft clearly marked and identifiable as being on government service and authorized to that effect.
Under Article 92 a ship may not change its flag during a voyage or while in a port of call, save in the case of a real transfer of ownership or change of registry.
Article 105 states that on the high seas, or in any other place outside the jurisdiction of any State, every State may seize a pirate ship or aircraft, or a ship or aircraft taken by piracy and under the control of pirates, and arrest the persons and seize the property on board. The courts of the State which carried out the seizure may decide upon the penalties to be imposed, and may also determine the action to be taken with regard to the ships, aircraft or property, subject to the rights of third parties acting in good faith.
The following also exists, but may not apply unless the Somali pirates have signed up to it - Conversion of Merchant Ships into War Ships (Hague VII); October 18, 1907
Unfortunately Q ships won't do.
Hval
Edited to add a further treaty