My post was referencing normal small arms, and handguns. Now if it is possible to arm your yacht with a .50 BMG, I think that might provide a little more of a protection against pirates.
Put a 4x ACOG sight on any accurate semi-auto rifle, and you can kill that RPG gunner at 400 yards, depending on the sea state. But the sea state affects both pirates and sailors, so that’s a wash. But AKs and RPGs will not be effectively in range until long after a good Western rifle like an AR with an ACOG has been in easy killing range. For sure. The point is to display weapons and fire warning shots early. Nobody wants to get shot. Warning shots into the water ahead of a vessel are a clearly understood message. Keep coming, the next on is going to hurt. If they don’t turn away, start picking them off. Actually do it. When AK-waving Somalis start falling, the rest have a change of heart. This has been done.