[netsharc]

I've read that they (the navies) are reluctant about adding firepower, because the pirates would so the same (or "natural selection" would mean the knife-wielding pirates will stay home and only the AK-47 and RPG-wielding ones will continue), which will mean all the ships would need defending against powerful pirates.

It's a bit like policing in the US.

A sister comment to yours has a saner opinion, I'd add why not fight the African poverty/corruption that cause these people to attack ships.

[ggm]

At one stage, non-armed-forces vessels were being permitted to carry semi- and automatic weapons under very stringent controls. If you imagine those locks on the duty-free drinks trolley on a plane, and upscale it: they could unlock the weapons in defined areas and were permitted to use force to repel attack from unidentified craft.

https://www.telegraph.co.uk/news/worldnews/piracy/8858159/Ar...

[TeMPOraL]

That obviously invites an arms race with pirates, and probably reduces survivability of the crews. That's why I asked about a different solution - where merchant crews are unarmed, but armed forces provide separate, rapid response service with overwhelming force.