I’ve read what I believe are all the posts re turbo tunnel fins and I would like to add my 2 cents worth…
Like all things there are some positives and negatives…first the negative, and it’s a big one. You absolutely cannot use this fin in waters where kelp grows without experiencing some frustration. This fin is a “kelp catcher” extraordinaire! It will catch kelp and pitch you off the front of your board faster than you can think “arrrghh!” It will also rip or snap full strands of kelp and drag them along with you. You can count on this for 15-25% or so of the rides you get in kelpy waters. The second bad thing about Turbo tunnel is the complete lack of customer service if you buy online like I did. The sellers do not respond to contact queries from the turbo tunnel website, nor do they respond to email replies from email they initiate (purchase confirmation). And finally a small but pesty thing when spending $80 bucks for a fin…you get a free t-shirt and they don’t stock size large…so you get what they send you. That may or may not be a problem for some of you.
The positive things are that this fin provides a great deal of longitudinal stability to the board. When nose riding (for definition here the front 25% of the surfboard) one can be much less precise in their footwork. Not to worry if you mis-step on the inside or outside rail, the board stays steady. Re nose riding I did not experience a noticeable difference from my other fin (Wingnut 9.5" Cutaway) re tip time. There was also no appreciable increase in drag with the turbo, although oddly enough the board feels like it’s dragging. But I can make as many “critical” sections with the turbo as with the wingnut. Turning the board with the turbo is also no problem. Whether you like to snap turn, throw a big cutback or make long sweeping bottom turns, the turbo tunnel did not fail and provided stability and drive throughout.
This feature of stability on the longitudinal axis of the surfboard is, I think, a big deal. Stability and lift can be built into the surfboard (shape) and to a lesser degree be enhanced by the fin you use (well, maybe not the lift). I think the claim turbo makes re lift is weak at best. Supposedly the built-in watershaft “sucks” the tail of the board down. That didn’t seem to be the case in my experimentation. Of course I tried the fin in a number of different positions in the fin slot and the further forward the fin placement, the “looser” the turns, but again there was no appreciable increase in tip time the further forward the fin was placed. (One might think this would be the case because the watershaft is deeper in the water, compensating for tail rocker.) I just purchased a Rainbow “Tomahawk” 10-inch fin. I’m interested in whether or not this fin will provide the same longitudinal stability as the turbo without the kelp catching defect of the turbo.
In Summary: The added longitudinal stability experienced with the turbo makes it worth the purchase. I think this would also add flexibility to a longboard primarily kept for smaller waves, in that the same longboard could be surfed in larger waves, where stability plays a more prominent role in the overall wave characteristics that would be encountered. Playing with fins is one of the funnest things you can do in experimenting around with your surfing, surfboard(s) and surfing style. Maintainng a “quiver” of fins is cheaper than buying a board every time you are looking for a change, and will add to your satisfaction and knowledge of surfing.