GURPS Spaceships, upscaling sizes

[Tyneras]

Going by wikipedia Titanic was 52k tons, making it SM+11, and had a capacity of about 3,400 or 3,600 total. 200 cabins per habitat system by default, at 2 people per cabin that would be 9 systems, though there would obviously be a difference between first class and steerage. That doesn't sound to terrible for a passenger ship.

With no automation (GURPS Spaceships 7 p.20) and assuming 15 crewed systems, the ship would need 450 crew, the Titanic's 847 would just about cover 2 shifts.

Increasing the passengers per habitat system and reducing the number of crewed systems likely helps make it closer to the actual Titanic. I've hardly accounted for cargo or fuel or other systems.