Answer:
I help boats park
I fly away as soon as you set me loose. People around you may slowly move away once they sense my presence.
What has one eye but cannot see?
What goes up and down but does not move?
What loses its head in the morning but gets it back at night?
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.