If someone falls overboard while you're white water rafting, you can use a long piece of thread as a life line. Sure it might be thin, but a line of thread is better than nothing. Throw them a line and drag them back aboard! Those white water rapids are vicious.
The person who threw you that line of thread is actually a centaur (せん). How kind of him. After you are safe you hop on the centaur's back and ride around to get the wind to dry you off.