My main foil quiver for winging for almost 2 years was the Lift 150 HAX, with the 220 HAX used for light wind days. I was having a lot of fun with those foils, but I wanted to try something new. I had a brief stint with the KT Atlas 790, and finally settled on the Enduro 900 (with the E1100 replacing the 220 HAX for light wind). I thought the comparison between the three foils was very interesting, so here is my review.
Rider and gear info: Seattle area, 70 kg weight (including wetsuit). All foils were used with Omen Flux 60 L board and 77.5 cm Cedrus Evolution Surf mast. I’m focused on upwind-downwind swell riding. E900 with HA38 tail. 150 HAX with extension and 26 carve tail. Atlas 790 with Atlas 170 tail.
Conclusion up front: the E900 has better low end AND high end than the 150 HAX. You can pump it onto foil at a speed where the 150 HAX would immediately drop. At the same time, the E900 can be pushed faster than the 150 HAX. The average speed from my GPS tracks has increased by 1-2 MPH with the E900 compared to the 150 HAX. Nevertheless, the 150 HAX has a magic speed window where the glide is better than the E900. If you can keep the 150 HAX in its sweet spot, it pumps and glides better than the E900, but if you make any mistake and lose speed, the 150 HAX stalls abruptly when you try to pump it. Also when powered up with a wing or bombing down a big swell, the 150 HAX seems to hit a speed wall. Overall, I prefer the range of the E900: it goes faster and I can recover by pumping from a much lower speed. The glide of the E900 is great overall, I’m just aware of a slight increase in drag compared to the 150 HAX in the narrow range where the 150 HAX works best. For light wind, the E1100 is better in every way than the 220 HAX.
The Atlas 790 has an even lower stall speed than the E900, but I didn’t feel like that extra low end range was very useful. The drag at those low speeds with a small area foil is very high. I found that I could pump the board off the water and be on foil without stalling, but the drag would still be so high that the wind power wasn’t enough to accelerate to real foiling speed. Note that I only had one session on the Atlas 790. I rode it for about 4 hours in 15-25 mph wind and tried 4 different shim settings spanning over the KT recommended setting. I think with more time with this foil I would likely learn to use the low end range better.
I struggled with the top speed and glide of the Atlas 790. On my GPS track the average speed of the Atlas 790 was 1-2 MPH slower than the 150 HAX. I could not keep up with the wind swell unless I was bombing straight downswell. I wasn’t able to build speed on a swell and use the momentum to get to another set of swells because the glide was too low. I could pump around at very high energy output, and keep pumping even at very low speeds, but at that point the drag was so high and the speed was so low that I wasn’t able to get back onto a swell. Again note that this is all based on one session and I’m sure I could learn to use this foil better with more time on it, though I have a hard time seeing how the speed limitations would change. I found the upwind angles with the Atlas 790 to be very good.
The KT system has the best fuselage to mast connection system on the market, in my opinion. Part of the reason I wanted to move away from Lift is that I don’t like how their system relies on a tight fit that can be worn down and get loose with use, though I have to admit I never had an actual problem with it. The AFS connection is almost as good as the KT system, but I would prefer the KT system if I liked the foils better.
I remain a little skeptical of the tubercle design even though the Enduro foils are working great for me in practice. I know what the marketing claims are, but based on my own intuitions (which are well informed though not in this exact field) and based on discussing the design with engineers who do work on airplane wings, I think the tubercles must add drag compared to a smooth leading edge. After being disappointed with the KT foils I bought into the AFS system based on the many positive reviews, and I have to admit that the performance attributes seem to mostly match the marketing claims. I will say that my observation that the 150 HAX has better glide in its sweet spot is consistent with my intuition about drag from the tubercles. My understanding at this point is that the tubercles lower the stall speed at some cost in drag. The increased rear camber of wings like KT Atlas, Armstrong HAV2, and SABfoil Razor try to make a similar tradeoff, but based on my experience the drag price from extreme rear camber is too high for my purposes.
Thinking back to when I switched to the 150 HAX from a large beginner foil, the transition was pretty difficult. I think if I had started with a high aspect high camber foil at that point, it would have saved me some frustration compared to jumping to the 150 HAX. Having fought through the challenges of the 150 HAX, I had gotten comfortable with it and loved the glide and pump. The Enduro 900 is a different tradeoff, extending the range at the expense of a small amount of drag. The high-camber designs are another type of tradeoff; my hypothesis is that the KT foils would be more forgiving for learning, and are likely at their best for riders in bigger waves, swell, and wind where the higher drag is less relevant compared to being able to get on foil with a small foil.
Overall, I have a hard time seeing a downside to the Enduro foils besides price, and the wing tips seem fragile.
TLDR: foiling is so much fun.