He lived in Stuttgart and his name was Hans Schwarz and he went by the nickname “Blackie.” In the 1970s, he had a boat and I met him in Spain and ended up living on his boat in La Coruna. We got stuck in a storm on the way to Lisboa, Portugal and limped back to La Coruna, where I left him. He came to visit me in the US once, but we lost touch at some point. He loves boats and motorcycles and could live anywhere now because, like me, he is a travel addict.
How can I find him now?
Sounds like a Hemmingway novel.
First, write the screenplay.
Second, sell it for a million bucks or more.
Then, when the film comes out, he’ll hear about all the publicity and contact you.
Or, failing that, you’ll have a bunch of money to pay for a private investigator (which would also be my serious answer-- hire a PI).
Well, anyway it sounds like a good start of a novel. I suppose you’ve already tried a Stuttgart phone directory. You might find one of those at a decent public library in the U.S., although I’m not sure about Trinidad. Unfortunately, Hans Schwarz is not going to be an uncommon name in Germany. Good luck!
A library? What’s that? 
There’s at least a couple German phone books available on the web, but I’m sure you’ve checked those.
So you’re looking for a guy named John Black. That’s gonna be a toughie, given the commonness of the name. Coincidentally, I have friends both in Stuttgart and La Caruna, and if there’s a resource you want me check, I can probably do it. Although, from the sounds of it, this guy could be anywhere.
The easiest way to find him would be through friends of his, researching waterever last leads you have (his last known phone number/location/etc), and piecing it together from there. With a name like that, and his penchant for travel, it’s gonna be nigh impossible to find him just via the internet.
Moved to IMHO.
-xash
General Questions Moderator
Jill you need to get drunk and write that novel you’ve always wanted write about.
Other than that, I got nuthin’.
You could always try an on-line German telephone directory…just google “German telephone directory” and pick your poison. Here’s one I found.
Of course, I suppose “Hans Schwarz” is a fairly common name in Stuttgart, let alone elsewhere in Germany, if he’s moved.
I just wanted to add to Duke’s link that it is maintained by the ex-monopoly Telekom, the (by far) biggest phone company here. All online phone directories use the same database anyway, but there you can be sure that you get the most recent version. If the number is listed in the phone book and Mr. Schwarz did not explicitly object to inclusion in an electronic directory (They added that box to the standard number registration form after some people were upset about the first phone book cds in the nineties,) it is there. Note that some people list only the initial of their first name and there is a slight chance that the line is registered to e.g his wife and he himself chose not to be listed.