To many, pirates are romantic, dashing and heroic, especially at a distance through history. The reality is more complex and messy than that.
As technological civilization on Eunesia slid towards its fall, Ulrik Svensgaard and his followers abandoned the land as soon as they could, seizing the few water-capable craft and all the available pelagic technology. They built their first bases on off-shore islands and in shallow coastal waters, seeking to explore and use the vast resources of the planet's oceans, hoping to stave off the collapse to Old Worlder or Cargo Cult status. They stayed aloof from the growing vendettas among the land-based factions, although they ruthlessly attacked anyone venturing out to sea without their leave. Soon they were being called the "Nautilus Pirates," after the chambered-nautilus symbol they had taken as their banner. And they had failed.
The Nautilus Pirates choose to live the sea-faring life, believing that Eunesia's oceans are actually more fit for human habitation than its continents. Aside from this commitment, they have no fixed dogma, simply pursuing the life of adventure and discovery that Captain Svensgaard promised them. The ideological imperatives of the three other civilizations on Eunesia amuse (or anger) the Pirates, who are not above raiding the "land-huggers" in order to puncture their pretensions.
The Pirates are not natural allies of anyone. They will trade with (or raid) anyone depending on circumstances. The best way to befriend the Pirates is to trade with them fairly, treat them with respect, and stay on land "where you belong." The quickest way to end up in vendetta with them is to encroach on what they regard as their own domain, the wide oceans of Eunesia.
The Pirates ritually maintain their pelagic technology (Pontus) and satellite system (Aether). Their ships are always of higher quality and have better-trained crews than those of any others on Eunesia. During their early years, they developed superb small-unit tactics focused on boarding actions, allowing them to capture ships built by other factions.
Their technology allows them to have economic advantages at sea. They can extract more resource value from the shallow waters of the continental shelves, and they are the only ones able to build bases and other facilities even in deep ocean waters.
The wandering existence of the Nautilus Pirates has certain drawbacks. Much of the cult's economy must be devoted to maintaining their oceanic bases, facilities, and ships. This leaves fewer resources for personal goods or industrial production. Further, the rootless Pirates have few children, and have difficulty maintaining stable families when they do. Much of their growth in population comes from recruiting disaffected members of the other civilizations.
The Nautilus Pirates live without roots, rarely owning permanent homes. Many of them live for years on board ship, relying on long-range communications to stay in touch with friends and family. Others use a series of temporary quarters, moving from one Pirate base to the next to follow their work or their personal relationships. As a result, private quarters in most Pirate bases are small and utilitarian. They do place some emphasis on community space, giving its citizens plenty of places to meet and socialize. These include some of the best bars and restaurants on Eunesia.
Among themselves, the Nautilus Pirates admire adventurousness. The ideal Pirate sets high goals for himself, pursues them by any means necessary, and attains them with style and panache. The tales of such accomplishments play an important role in faction society. The Pirates' preferred art form is the story, either set down in print or told over beer in a public place. They hold most other art forms in contempt, but their narrative literature is notable.
The Pirates have a political system barely above anarchy. They believe strongly in personal property, at least among themselves (the property of non-Pirates is far less sacred). A shipowner or businessman can run his affairs as he pleases, and his word among his employees or dependents is law. Competition between such figures can be very fierce, involving brawls or sabotage as well as legal or economic maneuvering.
The system often seems on the verge of breaking down, but there are factors which prevent competition from getting out of hand. The Pirates have a well-developed code duello, so bitter enemies can always resolve their dispute personally before others are forced to suffer. Meanwhile, Captain Svensgaard's descendants form a semi-formal police force, stepping in with highly-trained marines whenever it seems necessary.