... and, while I'm not certain as to its 'completeness' in the search, to target a particular thread only, you would have to use something like duckduckgo for the search engine. You go to the first page of a thread you want to search, and copy the address. Then go to duckduckgo and type "site:" in the search box, and then paste the copied addess. Doing such with the FotRSU thread would have a search term like
"site:http://www.subsim.com/radioroom/showthread.php?t=226270 sampan"
which would yield this hit:
http://www.subsim.com/radioroom/show...73#post2564673
If you do a similar search in google, it will find many more hits, since it searches the site and not just the thread. You might be able to limit the search with their Advanced settings, but it's easier to use duckduckgo. Although, as you can see, it doesn't get the new "hit" of your above post...