roadrunnner did a history post back in November about the different iterations of Turbo Fins...
To most users, Turbofins are Turbofins -- they all look alike. But without a lot of fan fare, Hobie has been steadily improving this product.
I believe STTurbofins are now in their 5th generation. Here's a rundown:
-- spring 2006 first generation turbos appeared
-- second generation enlarged chain clearance notch for better fit
-- third generation changed black outer material for more durability. Identifiable by a small "T" (tough) near the upper right corner.
-- fourth generation changed gray inner material for improved performance
The newest (fifth) generation again upgrades the outer (black) material for better puncture resistance, improved rip resistance, better cut resistance from fishing line and better shape retention on the trailing edge. I got to "torture" one of the new fins compared with the previous version recently and was thoroughly impressed with the differences. On the water, this new fin handles submerged strikes with greater resistance to punctures and require no patching if somehow you manage to puncture the fin anyway. So far I've had several strikes against submerged stumps and no tears at all.
Trailing edge stretch, while not seriously disruptive to typical fin performance, is unsightly and can cause uneven leg exertion (see picture):(photo by wndrfl)
It is caused by resting the trailing edge against surfaces for any length of time, particularly warm or hot surfaces. The new fins appear to be remarkably resistant to this stretch. I've had the new fins now for over 2 months and without any special handling or sleeving, they still look like new.
How about performance? Oddly, the new tougher Turbo is more flexible than the former version, allowing it to operate with a little less resistance. That said, you'll be running a slightly higher cadence to cruise at the same speed. The difference is very slight. In terms of efficiency, the net energy expenditure is virtually identical to its predecessor.
Since all Turbos look alike, how can you tell the difference? The current version has a small patent number near the clew adjustment screw as seen here:
None of the earlier versions have this.
If your older turbos are looking and running well, you probably won't notice much difference in this latest version. But if they are looking a bit beat up, patched up or stretched out, take heart that your next set will be a great improvement!