All the cruise ships on which I have been a passenger had a shotgun or two for trapshooting off the aft deck. Surely a speedboat full of would-be pirates could be discouraged with a few whiffs of birdshot in their faces.
Water cannons are far more effective, sink the boats while they are approaching. Leave the drowning rats to the sharks.
They'll see your bird shot and raise you some RPGs and AK 47 return fire. These guys are armed to the teeth.
Something tells me that realistically more firepower than that would be needed. My first weapon of choice would be some .50 cal machine guns mounted at strategic points on the ship and lots of ammunition but I’m not really an expert.
Not with the armament that a lot of modern-day pirates wield. Submachine guns, assault rifles, pintle-mounted machine guns on their speedboats, explosives, grenades, all sorts of black market small arms. It wouldn’t surprise me if there were pirates running around in the Indian Ocean with heavier stuff like grenade launchers. A couple of trap-shooting shotguns would be useless against pirates that knew what they were doing and struck at night.
}:-)4