SWM wrote:So, the question is, what would make a good pirate ship, for an ambitious and well-funded would-be pirate. The answer is, the same kind of ships that are being used to hunt pirates.
They have the same functional requirements.

Speed, stealth, modest magazines, boarding crews, and low cost. Most pirates make do with less, because they either can't afford the money or manpower for better, or because they are trying to do it as cheaply as possible. But if you were ambitious you would want something pretty similar to the pirate hunters.
Largely. The pirates have tighter budgets and need to capture merchants, sometimes against the will of a nearby warship. The warships have backers for their whole operation, not just part of it, and can capture or destroy pirates, definitely against the will of the pirate. So the pirate needs less firepower, defenses only in case they come against a warship, and prize crews.
All a pirate
needs is to be able to catch and crew merchies and evade warships. Being able to fight a warship is a luxury, or a ticket into a richer market, but for a price. The warship needs to have the defenses (and firepower, speeds, sensors, etc. - but the defenses are the thing that sticks out most) to handle, easily, the toughest pirates they can expect to come against often. (Exceptional pirates you can accept handling with trouble, with help, or by punting them to a larger force.)
Oh, and the warship is likely to be built so that it is adequate against other warships too, just so it's not a strict pirate-hunter, unless it can be deployed where that's all the use you will ever have for it and can count on always having that use for it. (It is possible no current Honorverse navy has that niche to fill, though the Silesian Confederacy navy certainly would have. Still, I suppose the Avalon CL may be able to serve that for the RMN for a long time after it is obsolete against other warships.)