When I was in Grade 5, I bought a book called "Back to the Titanic". In the book, a survivor who when the ship went down was a boy in third class managed to build a time machine with the intent to go back in time to the Titanic; presumably to stop it from sinking. However, he broke his leg so his plan seemed to be a bust.
However, two of his grandchildren and their friend found the time machine and figured out how to get it working and they went back in time to the Titanic hours before it struck the iceberg. They met notable people and one of them saw his grandfather as a child at one point.
In their attempt to warn people, many people were dismissive believing Titanic could never sink; even with an iceberg. One of the kids was leaning towards Titanic hitting the iceberg head on. In the end, they failed; Titanic strikes the iceberg just as she did in real life killing 1500 people. However, the kids were able to return to the present day and told their grandfather who made them promise not to go back to the Titanic again.
Some of the people the kids encountered were:
Officers Boxhall, Lighttoller, and Murdoch.
J. Bruce Ismay.