Anything on or in the water is sinkable..........by virtue of the fact that it's on or in the water.
And, in fairness, Titanic wasn't a battleship............when the good lady's brother moved to NI, he was in a taxi, and they drove past Harland and Wolfe. The driver said to him "That's where the Titanic was built, you know."
He (jokingly) said " I wouldn't brag about it, though !"
With a totally straight face, the driver says "It was fine when it left here !"