The Olympic class ships, of which Titanic was the most famous/infamous, are impressive and I get why you would want to include it. However, its probably about 3 times the length of any of the ships in the base game and was designed to cross the Atlantic Ocean. Most (all?) of the ships in Transport Fever are river-capable as well, something that Titanic is not. Unless someone bootstraps oceans and oceanic seaports to the game, I doubt this will be a thing. Sorry to break it to you.
Keep in mind I'm no modder, so if anyone more knowledgeable can prove me wrong, go ahead and make Zanthia's day that much nicer! 
