I found the term *sub-base* [in *To Have And Have Not*](http://archive.org/stream/ToHaveAndHaveNot/TXT/00000098.txt) 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?