I found the term sub-base in To Have And Have Not by Ernest Hemingway (1937):
"We'll have to steal the boat. You know they ain't got her fixed so I can't start her."
"How you going to get her out of the sub-base?"
"I'll get her out."
I can't find this word in any dictionaries, either online or offline. I guess this is a kind of basin for boats or yachts. Is it a building for holding boats?