The first step in navigation is working out where you are. Think of it in this way...
You are riding your bike to a friend's new house when you become lost. No problem: you have their phone number. After hunting for a while, you find a phone booth and call your friend. Once you have explained the problem to your friend and asked for directions, the very first thing they ask you is...WHERE ARE YOU?
At sea, the problem is the same, only there are no phone booths.
