Hi Rubini,
as pheraps you know i'm currently in La Spezia where i'm an Officier of the Italian Military Navy since 1989....
My grandfather was here too during WW2 as officer of the 10à MAS navy force and even as submarines crew member.
By that i can stat that in La Spezia there never been any kind of sub pens and submarines was (and currently are) ever simply docked to a wharf.
Actual view of La Spezia arsenal: