I read this book when I was younger and can't remember the name of it.?

Ok, I don't remember a lot but if anyone if can help, that would be great. I remember that cover of the book was orange and I think the started with a "K", I believe it was the girl's (main character) name. She has a prosthetic leg and lives on a boat. She rescues a whale and becomes very attached to it. I don't remember what happens in the end and I know this isn't a lot of info but if anybody knows the name of the book, that is fabulous! Thanks in advance for the help. =)