How to show the answer graphically

[Aussiebear]

A recently put to me quiz question went as such:

Each day at noon a ship leaves La Harve for New York City. At the same time, a ship leaves New York City for La Harve, traveling the same route in the opposite direction. The trip lasts 7 days and 7 nights. How many ships will you pass on your journey? Show graphically, if possible.

I believe the answer is 4. How can I show this graphically?

Edit: If you were the initial ship then you could only pass 4. However the Question did not state this, so assuming you were in a continuous pre existing rotation then I'm guessing its 7