Thanks!
Also very interested in hearing anyone’s back to back reviews with the Katana as that is what I’m currently riding
That would be great but there’s no financial incentive to do it. If one mast was substantially better than another we would know about it based on collective user opinion.
I’m going with mast drag being such a small percentage of overall system drag (with 25% or less submerged) that any of the top brands will do 
I reckon it is a suitable masters level research project for someone in that space. Pretty common for a final project for someone to intersect their hobby with their research. eg this guy. It would be interesting to measure cavitation angles too as that is all theoretically determined.
Sure with 25% but that is unrealistic. I agree with Kane here. I don’t wing that much but with the wing the drag doesn’t matter, but for prone it is big, when your lungs are the engine then it is more apparent.
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I’m chiming in because my name is being thrown around and because incorrect data continues to be shared.
The A in the drag force equation is REFERENCE AREA. Depending on what your are analyzing, this may be more directly related to FRONTAL AREA but in the case of wings, it is typically WETTED AREA. Which number you use depends on how the Coefficient of Drag (Cd) was empirically derived, and I can tell you that no one designs wings or tests them in wind tunnels to generate a Cd based on frontal area. In the case of aerodynamics (or hydrodynamics), wetted area is always used. If you want to analyze a car driving down a freeway with 3 fingers out the window like Steve does, then you can use frontal area, but make sure the Cd is relevant.
I am beyond burnt out on the thickness discussion. Countless analyses have been done, from guys like Cody and Inde Foil, and I have personally paid 2 America’s Cup Foil designers (Steve decided to teach himself CFD because he fell out of his chair at the quotes), and every single analysis confirms the same thing: thickness is really not that critical for drag. Especially when you look at the whole system (wings, board, etc). But no one wants to believe the data. It’s like the movie “Don’t Look Up” or the current climate crisis. It’s not even a masters project, it’s literally basic engineering that a structural engineer like me has figured out and can be confirmed with a simple review of wikipedia. Now don’t get me wrong, I’ll give you a sneak peak that Evolution Cedrus is 16mm. But the way I really cut drag? Chord length. Evolution Cedrus will have less drag than NoLimitz V2, despite being thicker in certain areas. And it’s going to be a lot stiffer, and stronger, and universal, just like it always has been.
So get out of the shallow end and stop spreading misinformation.
Kyle
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Thanks Kyle!
I suppose it’s similar to a concept most know here and can feel. The foil drag and speed follow the same principle. A mast is just essentially a vertical foil.
As reference area A, do you break it down into percentage of what contribute to total drag?
A%= A1% (thickness)+A2%(chord)+A3%(other factors, like finish etc)
Good on ya Kyle for chiming in. Great topic.
Sorry you’re burnt out on the thickness topic. My guess is most peoples life experience is telling them that the thinner foil has less drag, formulas be damned. But does it actually matter, even for elite downwind SUP foilers? This seasons race results say NO. Both thick and thin masts finishing in the top five so for an average punter like me who is just winging with most of the mast out of the water, it’s all irrelevant (but fun to discuss).
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Hey John, the Cd accounts for the thickness/chord length or shape of the body. It will also factor in the surface finish, if the tests are conducted at relevant Reynolds numbers. But let’s keep it simple and ignore that for now. Cd is completely independent of size. So a big wing and a small wing can have the same drag COEFFICIENT, which is why you multiply it by a reference area to get total drag FORCE. As you point out, the mast is just a vertical wing, and the majority of the drag comes from friction between the passing water and the surface of the mast, as opposed to form or pressure drag which occurs when you try to push the water out of the way (like a truck driving down the freeway). Therefore, the more relevant reference area for calculating drag force is wetted surface area. Another way to think about this, is that a thicker mast will have a higher Cd, but the bigger term is still reference area (wetted area).
I can only share two links, but let’s start with these, until I have a more detailed explanation on my blog.
Drag (physics) - Wikipedia (I like this one because it shows the difference in types of drag between a streamlined body and a flat plate traveling through the fluid, and why frontal area makes no sense as reference area for a foil shape. Note that reference area in this example is for a sphere and therefore dependent on cross-sectional area, not surface area as we have discussed).
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The other thing I’m burnt out on is super passive aggressive and flawed marketing. I have been open and honest about my R&D with an active blog since 2018. I don’t know why some brands are so intent on proving me (and the laws of fluid dynamics) wrong. Fortunately I’ve been able to tune it out for the last 8 months while I work on Evolution Cedrus, and I think you’ll all be pretty excited about the final design and improvements made.
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The proof is always in the eating, I currently ride the F-one HM 14 and its night and day less draggy than the Cedrus mast which I used to own for a quite a while but sold for this reason. To be fair the Cedrus was out like in 2018/19 and its not fair to compare it to a 22 state of the art mast.
I really wish Kyle all the best for his new Evolution version, I’d buy it if I tried it and it was better.
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@ProjectCedrus Kyle I agree that the explanation above doesn’t really make sense, I couldn’t follow the logic and I would think @NoLimitz account should probably have asked Steve to formulate the point directly. The drag calc is wrong, A is not the divisor in the formula?
That said, Kyle I didn’t entirely follow your blog either, as you used this graph (I’ve annotated it below, added some highlights etc), but you never explained what it was based on, what assumptions you made nor what formula you used? I now broadly follow it but initially would have made sense to explain it more completely.
So I’ve guessed based on what you’re saying that your chord is around 110mm or at least less than 118.9mm? (Nolimitz tapers down to 118.9mm, so I’ve approximated that, with a guess at where things land)
Something that I’m not clear on is the angle of your “more than / less than drag of cedrus” line. Perpendicular to that line is an implied linear relationship of some sort? Could you help me understand that? Is this just setting the parameters of the equation and then varying the reference area?
We absolutely believe that mast profile thickness has a direct impact on how fast a mast is. This belief has been validated through continuous feedback from the best riders in the world. In our 3 years of offering our foil masts to the market, we have not criticized our competitors online. We will continue with this approach and let our masts do the talking.
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This post is so so so bad. I can’t even begin to dig into everything that is just plain wrong throughout the entire post. But I can’t let this particular bit pass.
- The formula given for drag is incorrect. Area is a multiplier not a divisor.
- The explanation of why thickness matters is exactly and completely backwards. Changing the Cd from 0.03 to 0.02 represents a 33% reduction in drag. Thickness going from 16mm to 14mm would only be a 13% reduction in drag. Clearly the effort should be put to Cd where there is an ability to make a big change.
- Even worse, the entire statement is complete garbage. As Kyle stated correctly, the area to use in the drag formula is the WETTED area, not the frontal area. Frontal area is appropriate thing to use for blunt objects not foil sections.
A thinner frontal area CAN result in a lower drag for the same chord. But as soon as the wetted area changes (less chord) its all out the window.
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Here’s the image of the formula that should have been used in the original post instead of writing the formula out:
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Redaction: “If you change the Cd from 0.02 to 0.022”…
In response to your third point, from Steve:
"I completely agree with Kyle. In hydrodynamics, wetted area is critical to the drag of a body. Hydro design is frequently concerned with hull shape as it goes through the water - bottom of a boat - and in that case, wetted surface area is far and away the predominate driver of how much drag you have to overcome. In the case of a lifting foil, you once again are dealing with wetted area as that foil presents itself at an angle of attack to the water so your Area of concern is the wetted surface.
Where we can agree to disagree is what has a bigger impact on the drag a mast produces: chord or thickness? A mast is not just a vertical foil, it serves a different purpose, and as the Navy has done extensive studies on, acts differently. Several large studies were done by the Navy on surface piercing struts, and those are what I mostly relied on as I designed our V2 masts. The mast is not designed to be a lifting surface (at least I did not design it to be a lifting surface - we can argue that yes it does produce lift at times but that is not it’s primary purpose). If we consider the angle of attack of the mast as being zero, the critical Area for drag is the frontal area of the mast and that is what I designed to. It is critical that the Cd used for your calculations is generated for the angle of attack and the Area you are use in your drag calculations, exactly what I have done in my design work.
All this discussion on thickness and chord ignores the #1 design criterial I was worried about when designing V2 - ventilation. I don’t care how fast or slow a mast may or may not be if the thing ventilates and throws me on my face."
We stand by our #30 statement above.
Why don’t the fastest kite and windsurf foils run super short chords for their thickness then?
Ventilation. You’re either foiling and going fast or you’re not foiling and going slow. Anything that causes you to stop foiling is the #1 priority.
My experience is that certain aspects of the airfoil design like thick leading edges and high thickness/chord ratios make the mast less resistant to ventilation.
The most stable masts I have tried at high speed are all around 10% t/c. A well designed mast like the Mikes Lab or NL can resist ventilation at higher thickness percentages, meaning the chord can be reduced for a better stiffness/drag ratio.
The higher your speed, the better a high t/c performs for drag but the worse it performs for ventilation. You also need a ventilation safety cushion if you want to add any raised graphics or expect any surface imperfections on the leading edge.
There are cases where thinner sections can perform better at low speeds due to lower drag coefficient at low Reynolds numbers.
Another factor is surface piercing drag. I am not sure what effect, it has if any. It could be a factor that we are not able to calculate.
If you can further reduce the chord without any sacrifice to ventilation, that would be a breakthrough.
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I’m going to address a few comments that have been made, and then any additional analysis re: this topic will be dealt with on my blog.
@Matt your interpretation of my graph is correct. The line I drew is constant drag FORCE of the mast. Lines parallel and to the left are less draggy, and to the right is more draggy. It is based on a DOE (design of experiment) that I had conducted by Tom Speer, the lead designer for Oracle Racing’s hydrofoils and airfoil (they were the first to launch a solid wing sail). I posted the details of my work with him over 5 years ago here: Aero - Project Cedrus In short, we looked at drag and separation angle (which is indirectly related to ventilation characteristics) for a matrix of masts 16-20mm and 100-140mm chord length. Note I did not go below 16mm for a reason: stiffness falls off a cliff. A 16mm mast is 50% stiffer than a 14mm mast. No amount of modulus can make up for that. Anyway Tom’s CFD incorporates non-linearities like piercing drag, parasitic drag, lift-induced drag… it’s all a lot more complicated than the equation that @NoLimitz posted. I have spent 20 years refining my skills in Finite Element Analysis (FEA) and spent $40,000 in software. I won’t pretend to be capable of teaching myself the same tools for CFD, nor can I afford them at this point, which is why I paid Tom. The analysis confirmed that drag is affected more by wetted area than thickness. Which kind of makes sense, because if you add 10mm of cord length to a 100mm mast, that adds more area on both sides of the mast. My statement about increasing chord length 10% causing drag to go up 20% was based on this analysis. Adding 10% in thickness only caused drag to go up 8%, because the wetted area did not change… you just slightly increased the Cd, which as @NoLimitz points out, is the smallest term in the whole equation! One assumption I am making in my statement is that the shape/profile is relatively constant. Obviously there are infinite ways to shape a streamlined body, and Tom designed one for me that works well at the speeds and Reynolds number that our foils operate at. But there could be some subtle differences in shape that make a longer chord length mast equivalent (or even less than) in drag to a similar mast with a shorter chord length, but again the trend is still valid. That miraculously slippery mast could still be faster with a shorter chord length.
@NoLimitz in my 7 years designing and offering masts, I never said mast profile thickness doesn’t impact drag. I simply said it doesn’t have as big of an impact as chord length (wetted area). Those are two very different statements. A direct quote from your V2 product launch: “Now, some folks on the internet talk about chord having a bigger impact on drag than thickness and that is simply not true.” Considering my blog post on this very topic, that statement felt like a direct attack on me and Project Cedrus. Further compounded by the fact that Steve’s analysis is completely wrong, I felt inclined to finally address this callout. As I’ve leaked, Evolution Cedrus is 16mm thick-obviously I know there are benefits to a thinner mast. I am simply trying to educate the community on the fluid dynamics, and you are hampering that effort by publicly criticizing my work on your website. I don’t know what the shape was of your Navy surface piercing struts, and if they were anything but a streamlined body, using frontal area could be applicable. The two links I posted previously show the use of frontal area as the reference area in the case of sphere moving through the air. But if we are analyzing a streamlined body flowing through fluid, with an order of magnitude longer chord length than thickness, the majority of the drag comes from skin friction and therefore wetted area will be used for the reference area. You can “continue to stand by your statement” but I suggest you actually talk to professionals because they will all agree that using frontal area is incorrect.
Finally, I have said nothing about ventilation in my posts. All of my statements have been related to drag, and only drag. I know all about ventilation. I wrote about ventilation in that same blog posting above back in 2018. I have another post on it here: https://projectcedrus.com/cedrus-development/notes-on-ventilation/ Yes my 6 year old Project Cedrus design suffers from ventilation at higher speeds with modern foils. I’m honest and open about that. It was a gamble I took making the stiffest mast in the industry (even to this day!), and honestly I have no regrets. But I have focused heavily on addressing ventilation with Evolution Cedrus, and can assure you that it will feature the most ventilation-proof design concept the industry has ever seen.
In closing, I didn’t mean to hijack this post and only chimed in because my name was used and people seem to be questioning my methods, assumptions, and analyses. I hope I’ve cleared them up, and if I haven’t, you can head to my blog for more info, or contact me through my site. Thanks to those who have supported me on this journey, it really means a lot.
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Agree with this - we have recently launched a new skinny wingfoil specific mast with sections optimised for low drag and low ventilation. You can really feel the difference in glide, but it is the smoother nature punching through the waves that surprised me most, plus the ability to ride with minimal immersion without venting.
We had to pay for this with a little reduced stiffness compared to our previous since both section size and t/C have been reduced, but overall it is a smoother, easier and faster ride when using ‘typical’ wingfoils around 1m span. Larger span wings / travelling slower might trend towards stiffer masts whereas faster smaller spans (kitefoils etc) would put more emphasis on lower drag and better ventilation behaviour.
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Hadou Brunner on a “Takallure” setup.
Kujira 2 1400cm2 and Allure 13.2mm (superthin !!!) mast.
Superb combo he says.
Mmmm…something does not fit here, no matter how burnt the Cedrus designer is with the mast thickness issue.
I love his mast design from an engineering point of view but the formulas and CFD he shows as proof that thickness is not that draggy do not fit my experience or the reviews i have found.
For me real world testing, towing platforms, towing and releasing behind a boat or something like that… would be more convincing than Americas Cup wizztech.
I bet a pro rider getting towed in calm water would pick the glidier mast instantly and with no doubts.
4 different combos of thickness/chord lenghts could be tested in this manner…clear the computer fog.
I am 100% sure something like this has been done.
What were the results?
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Although, I am na engineer and use pretty advanced numerical computing techniques at work my foiling choice are purely experimental. And for whatever reason very thin Mike’s Lab masts and foils are way ahead everybody’s else. Extremely high performance and extremely user friendly.
Ride whatever feels good. Perhaps the Phantom Drift mast is the one for you two at 11.7mm. Looks like a very long connection point at the fuse so probably can’t be adapted to anything else.
Apparently they “…providing instant glide to the entire foil” 
Only about $1800 USD.
Thanks Kyle, part of what I enjoy about this is that most of the people involved are driven primarily by their interest, and you taking the time definitely is appreciated. I fall into the category of people who didn’t understand the dynamic of thickness vs chord length.
A few questions:
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How are manufacturers getting 11.7mm? This is where I think because you have an advantage being a materials expert there is an opportunity to push this? Mostly just curious.
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What about a faster “light rider” mast. F-one have two carbon masts. Unifoil have two carbon masts.
Two observations:
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you are maybe onto something with your modularity approach. If I can more cheaply access other foils, this is an interesting differentiation. Tricky with engineering.
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As others have said, the proof is in the riding, people buy based on feeling not physics - I’d try to get Adam Bennets to test it, he is probably the only person riding at a level high enough to offer relatively objective feedback. Every other rider is influenced by some brand affiliation. My 2c.
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