Axis Fatty vs. Cedrus Clydesdale
We've been getting a lot of questions about how our new Evolution Aluminum Clydesdale version compares to the new Axis Fatty mast for dock start and pump foiling. We're almost as excited about the Clydesdale as we are the Forged mast, because it's our first foray into the growing world of dock/wake/pump/scoot/experimental foiling. We knew throughout development that it was the most torsionally stiff mast we'd ever tested, with bending stiffness approaching and even exceeding some UHM carbon masts. Prototype Clydesdale and Forged masts were tested on the water with 2m+ span foils both downwinding and paddle-ups. The feedback was unanimous: Both of these masts are stiff enough for any foil you can throw at it. The Axis Fatty wasn't revealed until AWSI 2025, the same time and place we launched our new Evolution Aluminum lineup. So with little information out there on it, we got our hands on an 80cm mast for a deep-dive, out-of-water comparison.
Weight: First off, despite being the same intended uses case, these masts are about as different as it gets. Material, manufacturing methods, dimensions, compatibility.... about the only thing they share is their weight: both masts way almost exactly 4lb, 14oz or 2.2kg. Note that to match the 80cm Fatty, a Cedrus 75cm + Adapter was used for all testing. They are within 1cm of equivalent length.
Cost: By using intermediate modulus carbon fiber, Axis was able to keep the price of the Fatty low for carbon masts at $1,174. The Cedrus Clydesdale with an Axis adapter is almost half the price at $650.
Compatibility: The fatty features a new beefed up mast foot that is only compatible with the Fatty fuselage. These fuselages are quite a bit more expensive than the original Axis red/black fuselages, but should handle the higher loads better. The Fatty plate mount does not have Foil Drive battery mount holes, and has a much bigger footprint, which will limit foil placement within the board tracks. The Cedrus Clydesdale mast is compatible with nearly every foil on the market (including both Axis fuselage standards) through adapters, and features Foil Drive mounting holes and a small footprint plate mount welded to the mast.
Drag: The Axis mast is big. Chord length tapers from about 150mm up high to 140mm at the fuselage end, with thickness also going from 23.5mm to 18.5mm down low. For analysis purposes, we are going to take mid-span dimensions of 145mm chord and 20mm thick, because most riders pump around the middle half of the mast. The Cedrus Clydesdale mast is constant 120mm chord and 20mm thick. At 5m/s (10kts), 40cm of submerged 120x20mm Clydesdale mast will create about 5.5N of drag force. The longer chord length of the fatty (+25mm) will add about 17% more drag, for a total of almost 6.5N. Even if we assumed the 18.5mm thickness, the extra 20mm of chord length over the Clydesdale offsets any gains from the slightly thinner section.
Now we've been pretty vocal about this for a long time, and this will be a different blog post, but mast drag really doesn't matter at low speeds. For perspective, a relatively high performance foil will generate 53N of lift-induced drag under a 185lb rider. This makes mast drag about 10% of total system drag. So even if the Clydesdale is 17% more efficient than the Fatty, it's only going to add up to a 1.7% gain since the mast is such a small portion of total drag. But hey, maybe that's the difference between getting up on foil or not, or pumping for an hour vs. 50 minutes.
Bending Stiffness: And this is where the Fatty lives up to it's name, deflecting only 6.2mm under an eccentrically applied 500N compressive load. Less than any mast tested in the history of our rig, and resulting in a stiffness value of 28.5N*mm/mm. The Clydesdale: 10mm of deflection under the same load, for a lower mast stiffness of 17.55 N*mm/mm
Torsional Stiffness: As we've mentioned in this blog entry, we don't know exactly how much torsional stiffness a mast needs, but we know it's important. Any time you turn your foil, either yaw or roll, you are inducing a torsional moment about the axis of the mast.We've found through testing and development that two surf masts with the same bending stiffness can feel wildly different with added torsional stiffness, and updated our layups accordingly. We have also heard from many Forged customers claim that the aluminum mast feels so much stiffer than their HM carbon mast, which is entirely due to added torsional stiffness because bending is in fact slightly lower. It's complicated and complex, and we don't plan to have all the answers right now or maybe ever. But in general, our masts feature what we believe is good balance of torsional and bending stiffness characteristics, both carbon and aluminum offerings. In our testing, torsional stiffness of the Fatty came in at 1380 N*m/rad, which is actually slightly lower than the Axis 19mm alloy mast. It's a common trend among claimed stiff masts, and the result of using primarily 0 degree unidirectional fibers and not enough +/-45 biased plies. The Clydesdale mast has the highest torsional stiffness of any mast we've ever tested at 2380 N*m/rad.
Sustainability: I'm only mentioning this because Axis chose to label the product sustainable (SSS), while at Cedrus it's a core value. It's common knowledge that composites manufacturing is a resource, energy intensive process, which is the primary reason we have invested so heavily in our new aluminum mast. Trek found through their analysis that carbon bikes have roughly 3x the CO2 footprint of alloy frames. There is nothing sustainable about carbon foil masts, especially those that use a lot of material. Cedrus masts are universal, repairable, hollow (less material), and forwards and backwards compatible; this is the closest you can get to sustainable. Absolute worst case, the Clydesdale mast can be added to your recyclables bin along with your beer and soda cans should you manage to break it. But no one has ever broken a Cedrus mast in the history of Cedrus, except for 1 customer who let his setup wash ashore in the shore break instead of using a leash but that is another story.
In closing, we haven't had a single complaint related to the stiffness of either Forged or Clydesdale masts, and are confident they can handle any foil you throw at it. We haven't ridden the Fatty nor have we seen much feedback from early riders. We just wanted to present some data, and feel the Clydesdale is a worthy alternative to the Fatty if you're looking for something with a little less drag, fully Universal, and more sustainable. The decision of what to ride is entirely yours.
