Star Trek Online is a game that's being built upon one of the most popular sci-fi IPs of all time. As such, gamers have certain expectations of the title, particularly when it comes to the ships they'll be flying. As with the Star Trek films and shows, the game will stick to certain ship classes and configurations, but the developers at Cryptic Studios also need to allow for customization within that system -- everyone wants to fly something that's unique in some way. Something that's their own. This customization was the theme of a recent Star Trek Online dev chat with executive producer Craig Zinkievich.
Ships in Star Trek Online will have defined purposes, with Escort (cannons, heavy attack rating), Cruiser (general purpose, large crew), and Science vessels (emphasis on deflector dish 'powers') to be in the game at launch. Of course, you'll be able to modify them in various ways. The producer explains that the customization options won't allow players to drastically alter the look or silhouette of any of the ship classes from Star Trek canon, but you'll definitely have options within your chosen configuration.