The Call of the Titanic by Lindsay Galvin

Young cabin steward, Sid, is proud to be working on the Titanic, the greatest stream liner ever built.

Clara dreams of adventure at sea, and discovers it the hard way as a stowaway on a much smaller ship, the Carpathia. Here, she meets a giant bear of a dog: Rigel, who has a reputation for mischief. What none of them can foresee is how they'll need each other on the night Titanic collides with an iceberg.

Or that an even more extraordinary creature might also answer their call