[Rodney King]

Did you know these merchant ships must sail unarmed though places as dangerous as the Straits of Malacca?

Are you sure? When I was in high school, I was the mail boy for one of the country's largest tugboat companies. They used to hire mercenaries every now and then when delivering a barge to certain locales, so somehow they managed to go armed.

[nathanbedford]

It is my understanding that they are reduced to using fire hoses to repel boarders because most nations will not permit visiting ships to posses arms. I know on private yachts off the coast of Venezuela (the Spanish Main) inventive captains fashion hiding places for their guns.

[LexBaird]

Did you know these merchant ships must sail unarmed though places as dangerous as the Straits of Malacca? Are you sure?

IIRC, the problem isn't that the vessels are armed on the open sea, but that the weapons are banned in most ports of call. If a merchant vessel can't dock because of the .50 cals on board, they have a hard time doing business, especially in some third world port where a bribe can get their cargo seized for "weapons smuggling".