As with all massive multiplayer-online games, ease of integration to player-run organization is undoubtedly critical to long-term success.
With ease of integration to player-run organization, content is insured to be continually generated with only minimal intervention from devs required, if required at all.
Devs: in addition to new marketing campaigns, you must provide ease of access for clan joining and clan management. Your players are your lifeblood, and if they are continually allowed to bleed, the game withers away with the sands of time.
P.S. I am unawares if player count is currently stable or not, I'm only providing my 2 cents here. Providence knows we could always certainly do with more captains overall.
P.P.S If lack of revenue is currently an issue, commandeer the Team Fortress 2 model and monetize customization of ships, flags, etc. Get a real cosmetic market up in this b, and you'll ensure a steady stream of revenue for time immortal.