As for as the Titanic being billed as the "Ship of Dreams", I'm not certain it ever actually was. At the time, contrary to popular belief, the Titanic was not the most famous ship in the world. The Olympic was. It wasn't until the Titanic sank that it became as popular as we think.
Cameron's film seems to have made "Titanic" and "ship of dreams" go hand in hand. I can't say the origin of the comparison, but I can offer something. The Titanic musical, which first debuted months before the movie came to theaters, features the following lines in the song "There She Is."
BARRETT, BRIDE & FLEET: (looking at the ship, overwhelmed)
There she is...
Broad and grand...
Ship of dreams!
BARRETT, BRIDE, FLEET & CREWMAN:
Take your flight!
Ship of dreams!...
She strains at her lines,
The smoke from her funnels trailing.
Her prow like a knife,
She'll cut through the waves unfailing.
Soon to be
Size and speed unexplored...
And I'll be aboard
That ship of dreams!
I hope that can help a little, for all it's worth.
Thank you all for making me feel so welcome! I have Lynch and Marshall's Titanic: An Illustrated History, so I had seen the "ship of dreams" reference there. I wonder if that's where Cameron and Stone and Yeston (broadway musical) got it?
When I was at the Cleveland exhibit I saw a couple things with that phrase on it and it made me wonder if it was a period reference to the Titanic, or a modern one? I see now it it probably modern, but if anyone finds an older reference to it I'd like to hear about it!
It very well may have stemmed from that book. Don Lynch, who was the author, was one of James Cameron's consultants on his film, and he also reviewed the dialouge. The Ship of Dreams reference may have come from him.