I have some new KT foils, they look great, but I didn’t get any documentation about the shim system. If I understand correctly, every front wing and mast has a number associated. You add those two numbers, and the result is the size of the tail shim (which could be positive or negative).
I’m using a Cedrus mast, so I don’t have the shim number for that part. Does anyone know what the shim number is for the carbon 77cm KT mast? I’m guessing that would be closest to my 77.5 cm Cedrus.
It’s most likely 0, same as the KT mast but could be slightly different depending on the drag of the mast or how cedrus measures their length.
If you find you like something other than 0, write it in sharpie on the mast or plate so you always remember.
Awesome, thanks for the quick reply. I really like the idea of the shim system. I’m surprised though that tail size, fuselage length, and rider weight don’t factor into the system.
For anyone wondering, the 77.5 cm Cedrus with KT adapter measures just over 80cm from the board side of the baseplate to the top of the fuselage.
I have the exact same questions. I wish there was some more documentation for the shim system. I have a 72.5cm cedrus and it comes out to about 76cm. The 77cm KT mast has shim number 0, but i wish i knew what the numbers are for the other two mast lengths for reference.
I’m also confused about the tails and fuse length not mattering. Does the shim system implicitly assume that one has the tail size the most closely associated with the front wing? (I got the 680 atlas front, but had to get the 170 tail since the 145 was sold out)
In one of the AWSI 2024 videos Kane explained: “I have made some adjustments in the tail and fuselage design to reduce the amount of numbers you need to add. So, simplified it down to just two numbers, super simple, tells you exactly what to do.”
I guess that must mean that the different size tails and fuses have different angles of attack built in
With another foil brand that I am using I have a couple of my favourite stabs that are made 3-4 years apart, the older one at the time when the fuselage’s angle was quite a bit different. And now I am definitely shimming these two stabilisers differently, when only swapping the stabilisers and leaving everything else the same. But I am also using these two stabilisers in different conditions. So at the end, who knows what affects what : )
That’s correct.
Every foil can use this system, but you will need 2 additional values for fuse and tail. I have set this up on a few foils, all you need is a sharpie and a lot of testing.
Having the user enter each part into an online tool could give essentially a perfect result but this way is much simpler, gives me a result I like, is self contained, and future proof.
I’m excited to see how it works for everyone and where things can be improved!
can you explain why the mast length matters to the tail setting? I could see how it might matter to compensate for mast drag - a draggier mast wouldn’t require as much tail downforce. Is your thinking that a taller mast also results in more drag and therefore less tail downforce? That would only be true if the rider is riding with the foil deeper in the water, no?
It’s not just mast drag but also increased pitch sensitivity due to the longer lever (mast length). Longer masts tend to be more pitch-sensitive than shorter ones, but adding just half a degree of tail angle for a 9cm longer mast helps mitigate this effect.
Within an appropriate range, increasing tail angle will help increase the pitch stability.
You can read the KT manuals here that explain it simply for both tail shimming and baseplate shimming
The KT website has a great tuning manuals for both the tail shim and included baseplate shim. The tail shim manual also has recommendations for shimming when using an aftermarket mast.
The baseplate shim manual covers when and why you might use one.
Both manuals are well written and pretty informative. I’m currently loving my Atlas 960 and 1130 here in the Gorge. Both really shine with the medium Nomad tail with recommended shims.
Has anyone found a good tuning for a 90cm Cedrus Evo Wind mast (95cm with adapter) with a Nomad 830 and Atlas 145 tail when winging in 18-22 mph wind? I’ve tried several configurations with various tail shims, mast positions, and baseplate shimming but can’t figure out a tuning that prevents the front of the board and foil from dropping out when I unweight or move my rear foot (gybing or pumping - coming up on the ball of my rear foot). As soon as I move rear foot the foil and board drop out. When I move my front foot back a bit first then move my rear foot that helps a bit but the nose still dives and isn’t a natural way to ride.
I also ride a Code 720S with the smallest tail (120R chopped) and have no issues with drop out when moving or unweighting my rear foot so must be something in the shimming of the KT set up that I’m missing.
Related, the KT fuselage with no shim seems to have a highly positive tail angle as a starting point, like +2.5 or +3.0 which I would think is the max to offset the effect of a longer mast (the positive shims are thinner than the negative ones and get thicker on the back of the shim as you move from higher negative value to neutral to positive shims). Perhaps I need more than +2.5 to offset the longer mast and/or the Atlas tail isn’t compatible with the Nomad front wing, at least not with this mast.
Anyone figured this out or have suggestions?
I feel like there’s a lot of confusion about positive and negative shim. In your case, bottom mount shim with the thick end aft is positive, so less front foot pressure and more nosediving. You should try more negative shim, thick in front for more front foot pressure.
you ride it with the smallest tail. I also ride the 830 with the smallest nomad tail and it requires some accuracy in foot switch due to pitch sensitivity. For winging i usually prefer to buy a medium tail due to foot switching and chop, less predictable lift, so probably a larger tail will make it easier, shimming could help as well
Make sense. Note: All KT shims, positive and negative have thickness variation at the rear/aft which implies the baseline, no shim, is the max positive angle and all shims get progressively thicker on the tail end. The most positive shim in the set, +2.5, is flat and thin. All other shims in the set +2.0 through -3.0 get thicker but only in aft. There are no shims in the kit that are thicker in the front of the shim.
Yep, good point but I ride all Code wings 720S, 615S, with a short fuse and chopped 120R tail (smallest) and the foil is still able to glide for a fraction of a second with no rear foot pressure. Like when I need to untangle my ankle leash or it’s under my foot, I can quickly lift up my rear foot to get the leash sorted. So I think something is fundamentally mis-tuned and it’s not typical pitch sensitivity that can be mitigated through time and riding technique - it’s drop out/ nose diving.
For the last round of testing, I used the most positive shims (-2.5, -2) thinking the 90/95cm long mast needed that offset with the most tail lift possible, but maybe I went to the extreme and it’s just too much lift from the tail causing the problem… that doesn’t make sense though since I assume when I pick up my rear foot the nose diving is caused by lack of lift from the tail. Anyway, I will try less positive to see if I can get more stability.
it’s interesting that shims only go one way. doesn’t make sense.
maybe a nomad tail would work better due to different lift across speed range that’s more adjusted to the front wing?
i had progression 140 with 13.5 and 14.5
i used to wing with the 14.5 and the kt feels somewhat more pitchy than the 13.5 0 shim.
i still find it perfectly ok to ride with 155 tail. old cedrus 80+5 mast and similar wind.
i think that the pitch instability is part of what makes this setup turn so well, but bad for foot switch. i am very advanced with foot switch due to immense amount of kitefoiling so i kind of switch legs at the same time in sort of a mini jump
It’s just hat the baseline angle that the tail is on is already pitched quite a bit and the shims either bring that down closer to 0 or beyond to negative.
I see, they flipped the frame of reference so that that + means more negative aoa rather than positive aoa. If you are maxed out on negative stab aoa (+2.5 in KT language) you are probably stuck with getting a bigger stab or longer fuse
