Our Hammock

Recently we got a Hammock.  It's striped and made out of thick cloth, but we only have one, and at first we couldn't agree on  it.  

One day we all sat down and devised a system for using the Hammock.  Our system is similar to the used by libraries for sharing computers, where if someone is using the computer you can sign up as the next person to use it and the erson currently on it gets 15 more minutes on it then has to give it up.  ours is basically the same, but the person in the hammock gets 30 more minutes instead of 15.