Mast foot standard

Are any of the brands nearing compatibility yet?

There are a few that seem to be converging on this one similar design (not sure what it is called?) (nolimitz has a great list of example connections)

It would be a power move if some of them standardised. I can imagine a smaller brand with less influence (or a brand that maybe wants to change their design…) to do something that is compatible with something else I especially see this as relevant for the mid range undifferentiated big brand foils (Naish, North, Duotone, Core, Cabrinha etc) who could I guess make an interesting proposition if going with their mast meant you could try other foils. Or if you buy their foils you could upgrade the mast etc

Are there any others that have this connection? How viable is this? (paging mast gurus Nolimitz, Cedrus)


AFS (only new silk line)

Fanatic have something similar

Mikes lab


ps I know this isn’t at all likely for 2024 or even 2025 given the cost, pissing off customers etc etc etc but I think standards are a certainty over a long enough time horizon

1 Like

We’ve made a “standard” foil mast since 2017. A planar butt joint relying on 2 M8 fasteners has proven to be an extremely reliable and cost-effective interface, with very few failures across thousands of adapters in service. Every structural failure of an adapter we’ve seen has been hardware related, and 99% of the time, it’s an M6. We have evolved the joint further with our new ecosystem using super strong/stiff dowel pins for improved alignment and strength. Having studied, and often reverse-engineered every foil connection on the market, we’ve never understood this style of interface. They drive increased cost and complexity into tooling of molded parts, and added machining costs of metallic fittings, without taking any load out of the fasteners. They are basically fancy butt joints. They are not the same as the deep tapered fittings (mortise and tenon) found on Axis and Unifoil, for example. We know some brands think they enable a “thinner” interface, but as we have proven (and based on the fundamentals of fluid dynamics), thickness is not as critical as wetted area when it comes to drag and we would never tradeoff the strength of M8 (or bigger) hardware for a slightly thinner joint of this style. The few fuselages we offer for Cedrus bolt directly to the mast using the same planar interface for a reliable, hassle-free, and arguably even more important: repairable interface.

We’re not betting on the industry standardizing. Obviously, we are betting on the opposite. We are choosing to focus on making the best mast in the world so that there’s no need for the industry to standardize. This will continue to allow and promote innovation in the areas of foil design, and give riders the ultimate freedom when it comes to choosing and evolving their setups.


By “this” you mean planar butt aka the pictures above found on F-one etc? So a key tradeoff is “thinner” leading to M6 for the planar butt?

Deep tapered fittings (mortise and tenon) found on Axis and Unifoil,

Broadly speaking this is the other category?

Fair enough. Standards going to emerge somewhere just like skateboards, windsurf and everything else ever but the points on which interfaces, when they happen and what the premature optimisation cost are etc.

All of the joints you show above have keyways. None of them are a basic planar interface. Yes, the tradeoff appears to be primarily a thinner mast at the interface by moving the “butt” to the mid-plane of the fuselage (instead of the mast). But the fuselages are so thin, they require M6 hardware.

Broadly speaking, yes the other style of joint is a mortise and tenon tapered fit. There are other more traditional butt joints, especially on aluminum masts, but they are less effective on 16mm thick masts because hardware loads are higher. I would say one of the most innovative interfaces was actually Inde Foil, which had an undercut in the fuselage at the trailing edge of the mast to manage the tensile loads. Pretty cool design, and patented (nice work Cody).

Standards will emerge. The industry converged on tracks, which is a huge improvement since when we started and there were many different board connections (Tuttle, deep, KF, KF deep, 165x90, 140x90). We see enough variability in each brand when it comes to their joint tolerences, that we’re pretty confident it would be impossible for the industry to converge on a standard. Unless, it were something simple… like a basic, easy to machine, planar butt joint:)


I assume there patent laws somewhere preventing companies from using existing designs which is why we don’t get standardization.

This is very interesting, and where I’d agree. Though maybe changes the dynamic to “higher performance brands make the call and lower performance brands conform”. Sure you see this all the time in your engineering background? I’m not saying that it is optimal, just that it is. (see USB C, even Apple coming around on that for better or worse)

nah not really, common standards prevent market capture so generally healthy afaik

The flat butt joint is almost perfect. The only complaint I have is that there isn’t any compression or friction going on (other than the threads) and I find bolts loosen more with this joint vs a tapered or pocket joint. I’m not anything close to an engineer, this is just my own observation having used many different systems.

I think brands are generally resistant because it limits their design flexibility (although I feel like the limitations of a flat butt joint are pretty minimal).


If we came up with a standard and then everyone adopted it that would be ok. But who’s going to do that? We’d need to build and test thousands of foils otherwise nobody would trust it.

More likely would be for everyone to start copying an existing design but then you get patent issues.

@rycpt standards emerge by market forces typically, vote with your wallet type thing. If someone offers a compatible version and it satisfies a need then market will reward them, then others follow and a standard emerges. De facto standards don’t need a governing body or committee. This is not me making up stories:

I don’t think there are meaningful nor defendable patents anyway tbh.

As mentioned, we came up with a standard 7 years ago and have offered to nearly every brand and every customer the specs to use it. It was essentially open-source, there was no patent on the Project Cedrus interface (the mast architecture was patented). We’ve shared the drawings, the CAD, any info needed to make fuselages/foils cross compatible. We’ve had people machine adapters on their own, 3D print parts, or make their own fuselages for Cedrus. We love it. But none of the big brands have wanted to use it, and that’s totally fine. They want to make their own system. Very few patents exist in this industry, which is why so many connections look the same. Patents are very expensive… with 12 of them, I know. We’ve chosen to patent our new Evolution interface because it is novel/new and offers significant performance benefits when it comes to compatibility and structural performance. As a small company with limited resources, we see IP as a good investment but do recognize the challenges of asserting patents. To address your concern @Velocicraptor, the 10mm steel dowels take significant load away 8mm screws which significantly reduces likelihood of hardware loosening and potential failure. Hardware typically loosens because it wasn’t tight enough in the first place, or it’s fatigued with time.

We will state it again publicly, if any brand would like to collaborate with us on a mast/fuselage interface, we are totally open to it. But we see what we are doing as attempting to develop a standard: One can easily use the 3x M8 screw connections at the foot of Evolution Surf or Wind to make a bomber fuselage connection.


fwiw I don’t necessarily want them to standardise, mostly started this thread out of a curiosity around how standards emerge organically.

This is cool :clap:

1 Like

I think the standard should be:

The top of the fuselage is flat, with two M8 sized holes a standard distance apart(like the hoped for tail standard), countersinks for bolts on the underside. That way the fuselage has full thickness, instead of a cut-out which allows more twisting deformation, I think no matter how you design it. Also any mast profile can fit, since its just a flat surface.


So something like this but flat instead of the 3 angle surface interface? I quite like the look of this? What is the drawback? This is essentially what I imagine emerging as a standard (pure speculation)

Yes - that but flat. The same thing I had with a Cedrus mast and a Stringy fuse. Maximum simplicity and minimal compromise. Eliminate any unnecessary “tolerances”.

The graphic you show is good, but overly-technical to fabricate as a universal standard. Universal needs to be simple, but allow for maximum design flexibility.


I think that afs example has two benefits: almost full fuse thickness, and it makes the buyer think someone thought about designing it! Seriously though, the testing I’ve done shows no movement in the flat joint btwn the cedrus mast and adapter. I’ve had the bolts loosen a couple of times, but some tef gel and tightness fixed that. You could have enough bolt holes to provide multiple options for mast placement, and still have more material than many fuses.

1 Like

my stupid consumer brain definitely thinks that flat on flat would risk twist etc. Are you relying on friction alone? surprised it isn’t an issue but then again I have no idea. Relies entirely on the M8 bolts for alignment?

I must say would be a pretty easy standard to adopt

1 Like

Yes, we rely primarily on friction and really tight machining tolerances to achieve exactly what @FoilFondler is talking about. It has worked well for many years and thousands of adapters. Of course there are always corner cases, which is why we introduced the Evolution connection. The dowels prevent any twisting between the two parts during super aggressive turns or impact, and do reduce fastener loads. With 3 holes to choose from now, we can find the best mix of two to use, or use all 3 without the dowels to achieve similar strength. A lot of thought/engineering went into this connection. It may look simple, but it is far from that. A lot going on at the end of Evolution masts with overmolded aluminum, carbon, and provisioning for all adapters, while remaining fairly low drag. No it’s not 12mm thick and 100mm chord length, but it’s a lot stiffer and stronger than any mast that gets that small at the bottom, which is more important to us making a universal mast for all disciplines of foiling and body types.


I should also note that on my k2 fuse, the slot is so tight and the angle so slight that I’m pulling the mast into the fuse with the bolts as I tighten them. In the past I’ve thought I’d bottomed out and gone riding, which bottoms it out, leaving the bolts loose. So no system is immune to mistakes is what I’m saying.

Why a standard mast though? Why not fuse? If thats the case then axis is kind of already working that way. I know a few designers like to prototype with it and a few smaller manufacturers make wing sets for it. Its an easy fuse to make wings for, much lower tooling costs etc.

Without adapters you’d need standard mast AND fuse.