Sunrise on Running Water

The evil vampire Lord Napier Sandridge seeks to flee the vengeful sister of his most recent victim, a young man named Lionel Paxton. The sister, Alexandra, has proven so persistent that Lord Napier decides he's better off leaving England entirely, so he takes his light-proof coffin and boards the largest luxury vessel he can find to cross to America: the RMS Titanic. As a vampire, he feels fairly safe, even though a vampire's powers are suspended when he passes over running water: the Titanic loads in the twilight, and his coffin is stowed deep in the hold.
Even when the ship strikes an ice-berg, Lord Napier thinks his chances are good - the accident took place at night, and surely rescue must come long before first light will cause him to burst into unquenchable flame. Mustn't it?