Finding information in large forums

[yerg]

We've got to the stage where because of the type of subject that our forum focuses on people are finding it hard to find the information they need.

397,000 posts in 34,000 topics
I can at times get 50,000 responses to a search. Which is a about as useful as doing a Google search.

I'm interested in hearing what people are doing to enable users to better access or find what they are searching for so these large responses become useful.

[H]

Out of interest, which search method are you using?

I guess you could consider moving old posts to an archive board that could be excluded from a search (you could even make it excluded by default)

[yerg]

No thought whatsoever of archiving stuff and excluding it because the information isn't dated.

What search method?
Didn't know there was an alternative to what was supplied by default.

I tried installing Tagging but it doesn't function (1.1.6) so that's gone by the wayside. I know it only works from this point forward but members are prepared to tag older threads.