When mooring alongside a pier (atraque de costado), what specific function do the 'Springs' (Spring de proa y Spring de popa) perform?

1. They prevent the vessel from moving forward or backward (fore-and-aft surging) along the dock face
2. They pull the vessel directly sideways away from the dock into the channel
3. They hold the fenders suspended in the water between the hull and dock
4. They supply 220V shore electrical power to the vessel's battery charger