Crossing the spring lines is not a necessity for them to perform their function- whether or not they would be crossed would depend on the configuration of the bitts on the ship and the bollards on the pier. Also, on a ship the size of a Liberty ship it shouldn’t be necessary to use two spring lines at each end in most situations. When delivered they only carried six mooring lines, which would make this difficult to do.
While it is not the preferred method, two mooring lines may be made up to a single bitt. This is done by taking as many turns as is possible around a single post of the bitt. This is often necessary at the stern of a Liberty ship, as there are only two bitts per side, with the next closest bitt located just aft of the main house.
Regards,
Chris Friedenbach
Crewmember, SS Jeremiah O’Brien