Most pirate havens are going to be within a parsec - there's a LOT of real estate given Marc's (and my) default assumption that Oort clouds and Kuiper Belts are not unique to the Sol system. Find a rocky core KBO, drill in, and drop some modular bases; forge some papers, and send it in on a relatively legit freighter.
Note that the major expenses are fuel and mortgage; without the mortgage, a freighter is able to make a lot of money. Of the 211k on the Type A, 155k is the payments. It loses money because of unfilled staterooms... a pure cargo version makes 30K per full 122 Td hold.
I've put a calculation tool in the tools folder:
http://travellerrpg.com/tools/shipecon0_2.shtml
I agree about the available real estate. I don't agree that finding a large, rocky KB/Oort body is that easy. I don't agree that setting up a base in which people would
want to live is that easy. You can send the booty out on some ship with a legal title. But now you're spreading the profits over at least a couple of ship crews, plus base personnel. You'd generally want it manned 24/7 with some means of making an unmaskable warning for incoming pirates if authorities show up (perhaps blow up a fairly innocuous but unique object within detailed sensor reading range).
If you're staying within one parsec, then there are probably only two or three target systems to raid. The more you raid, the more they want to find you. If you spread out to many systems you make a smaller dent in the traffic, a smaller blip on enforcement radar, and less of an obvious pattern. With a J2 or J3 raider you can look for a much larger field of plunder.
Unless one posits that piracy is so easy that they set up camp every couple parsecs... that's a whole lotta pirates.
Any time a ship can operate without mortgage payments vastly increases profitability. But piracy introduces additional risks. The typical trader rarely encounters piracy, but the pirate always has piracy encounters and likely combat. Combat means ship damage, which can be more expensive than mortgage payments.
Combat damage also requires a shipyard. So, if your pirate base is going to include a shipyard that requires vastly more expense to set up, and many skilled hands to fold into your pirate culture. Which, again, means shares of profits are smaller. It requires a very identifiable supply chain. To disguise that means sourcing those supplies from varied and distant manufacturers, which means repairs to primary equipment (drives and weapons) will be delayed compared to a legit yard.
If your base doesn't include a shipyard, then you have to take your damaged pirate ship to a yard that will work with pirates. Can you trust them to keep your secret? How easily can that secret be broken?
How many civilian (i.e., non-pirate) eyes can notice there's something suspect about that one ship that's been here with battle damage six times in only two years? If the shipyard is willing to work with one pirate crew (perhaps due to personal connections) the danger is minimized. The cover story could be anti-pirate patrols of varying success. A pirate haven is different. More than one pirate ship is going to be a repeat customer, subject to suspicion by residents, repeat traders, or even passing travelers.
Perhaps pirates tend to use a ship up and discard it as soon as a captured ship in better shape can take its place. Ok, that also makes tracing them trickier. But then almost any ship the pirates are using will exhibit battle damage which can attract unwanted attention at legitimate ports. Only the rare capture with easily covered damage will be useful for taking booty to port.
But that means this one ship will be identified with cargoes that could eventually be traced to pirated shipments. Sure, things may go unnoticed for a while. But the more stuff the pirates bring to port, the more stuff that can be traced. It might be traced by pattern long after the trades were actually executed.
Bounty hunters would pay brokers and port officials to obtain lists of ships and cargoes across many ports. Successfully uncovering a pirate would be worth an insurance reward of perhaps ten percent of every ship and shipment that can be traced to that pirate. Bounty hunting a moderately successful pirate could be far more profitable than the piracy itself, just by turning them in and letting the authorities take the risk of apprehension.
Actually chasing down and apprehending that pirate can be accomplished by the bounty hunter after the pirate lands or docks at port in some cases, eliminating the risk of combat and expensive repairs to their own ship. Then they get the insurance reward and a percentage of the pirate vessel value. If they have a powerful fighting ship themselves, it may be worth laying in wait at an expected port of call and taking on the pirate ship when it appears. If successful, the claim percentage of the pirate ship is that much higher.
The examples of pirate havens from the nineteenth century don't really compare. The spread of information in that age was both extremely limited in extent and slow to travel. Not so in an information age. It becomes trivial to maintain a record of every ship, every crewman, and every item of trade. If port X seems to keep sketchy record of ship traffic, somebody can drop passive sensors nearby to record flight control and ship transponder transmissions that would, by necessity, be unencrypted. Encrypted comms would also be picked up, sorted by source, and preserved for later analysis.
If the pirate can't be chased down because they've ditched the ship in the months since the last visit, the authorities can investigate the port personnel. They won't be gentle, and somebody is going to give up the pirates to save their own bacon.
No, I'm not convinced that anybody can make a career of piracy. One is more likely to run into protection rackets and other lower risk criminal behavior and official corruption. "Captain, these engine parts are way overpriced, and I'm not convinced the proton converter needs to be replaced." "Yes, but the Syndicate controls this port. If we don't buy their overpriced parts and labor, the repairs take much longer and something will break down before we've gone three jumps. And don't even think to come back and get repairs on warranty."
