Personally, I would feel safer in a small boat, like no bigger than 24-25 foot.

And about sailing around the world: Many people do it, including elderly people and disabled people. When you are not racing, you can pick your weather time carefully for each passage, and spend as much time as you want or need to do it safely.

For a 13-year-old girl, I would worry more about her safety when she is in port than when she is out on the water.