What's the current experience and wisdom?
You know those Aussies have a great sense of humor and are quick to pull pranks on each other (and anyone else gullible as well). I think this was one of them. This was supposed to make the boat go faster. Of course, not only does it go slower, but the boat rocks back and forth due to the unbalanced nature of the mismatched fins. Here's an ST/ST Turbo combination:
Here are a few others that haven't fared so well either:
It never hurts to try out a new idea though -- you never know when one might work!