Well, it won't help much with something like "u-boat" but if you leave out the hyphen and just put a space you will be able to get the hyphenated author names.
I did try searching for "u boat" and naturally it came back with everything that had "boat" in the subject, but it did find the posts on u-boats - you just have to wade through a lot of stuff about boats in general to find them. Your best bet for weeding out more of what you aren't interested in is to use advanced search and narrow the search for 'u boat' to specific sub-forums, like History or Biographies, etc.
Reality can be beaten with enough imagination.
- Mark Twain