What's the Name of That Book??? discussion

I read a book about a year ago about a girl who moves to Ireland from America because of her dads job. She meets a boy and his sister at school. They have an older brother who seems really hostile to her. She falls for the guy she meets and I think he works at a yacht club or something.
I think she was afraid of water?
It turns out that all three siblings and the girl from America can control the elements.
Then they are told that the American girl and the guy she likes can't be together.
If anyone could help i'd really appreciate it.

Carrier of the Mark?

Ahh yes! Thank you so much :)