Peace, the problem, as I see it is that it is a violation of international law to carry arms unless you are a military vessel. Private security forces are illegal and expensive.
If an American ship was to dock in any foreign country they could be searched and any fire arms could be confiscated.

Some time ago there was a cruise ship that had a weapon in the form of a high pitched sound that was extremely painful to would be pirates. It is no doubt very effective and very expensive, but cheaper than millions in ransom.

Looks like another example of what happens when the law abiding citizen complies with the law banning guns and the crooks are armed to the teeth.