First experience: I bought the fins from Jacques vd Hout, he never used them. When I got the fins the quality of the foil is good, leading edge nice sharp, trailling edge has a interesting design. It was quite hard to find the difference between both sides, the asymmetrical profile has minimal differences between Port and Starboard tack. (especially when compared to C3 Strike)
On the water: I used the fin first in La Franqui, France. In difficult gusty conditions I found the fin working excellent!! Great control during the downwind part, upwind wasn't really good. The difference between starboard and port tack is bigger than I would have expected. The starboard tack has great performance + control in a small range of conditions. I used the fins under the falcon speed and the monoconcave didn't seem to be a problem
Efficiency test: The second session I tried the fin in lower winds, it became clear that the fin doesn't allow easily twice the windspeed. But it is possible to go twice the windspeed, but any small windgap will make it hard to keep nice balanced on your board. Here the swept back + low COE doesn't work out.
I think the fin gets better and better the stronger wind you will get, you could say a small range, or you could call it an outright world speedrecord design. For lowwind efficiency there are easier findesigns on the market. Conclusion when the wind is blowing 30kn+ and you're aiming 1.5x the windspeed, upwind course is quite flat than the KA lockwood Mcdougal Asy series will be a good choise. I really believe Spotty+Lockwood their 50kn can't be improved with most other findesigns in strong winds. This is a good strong concept, and it works underneath any speedboard! I definitly would look for the same principles as this fin for hardcore speed, but than in carbon design to give a nicer respond speed.
I would NOT recommend these fins if:
- there is no sandbar or other flat water around
- you always windsurf in 25kn winds or lower
- your topspeed is below 35kn
- the sandbar is on Port tack
- the upwind part is very choppy >0,5m waves (or choose to walk...)
- your board has a wide taildesign >30cm one foot off