Stereo Carbon Fins

Alexander Sarasitis, founder and owner of Trygons, was probably the first to ever make carbon fiber blades for free-diving, back in 1991!

Nowadays, in Trygons it remains one of the top priorities:
Finding ways of improving swimming efficiency. The latest outcome is the Trygons stereo-fins series.

Freediver with carbon fiber stereo fins in swimmingpool


Trygons RX Stereo Carbon Fibre Fins


The new Trygons – Subgear foot pocket and fin is the result of a 2-year R&D project on what is one of the most important pieces of freediving equipment.


The new fins have been improved in 6 key ways:


1) Quality & manufacturing technology


2) Efficiency (hydrodynamics & carbon fiber blade)


3) Comfort


4) Adjustability


5) Durability


6) Value for money


More analytically:


1) Quality & manufacturing technology: The Trygons RX Stereo Carbon Fiber Fins are made with the same technology used to make racing cars and aircraft. We have selected the finest German resins and carbon fibers available and use the latest and best reinforced plastics technology (the autoclave method with a PLC controlled curing cycle). This method offers the highest possible fibers to resin ration compared to any other procedure.


Fiber fabrics are cut by a robot, resins are vacuum infused using a PLC controlled sealed stainless steel mixer and molds are vacuumed with a 99.9% laboratory vacuum pump. Following this, the blades are compressed at 8 bar inside the autoclave and cured up to 120° Celsius (accurate to ± 0.1°C).


We chose to use resins that are stable up to 120°C instead of the recommended industry standard of 80°C. Why? Because in the past we have recorded surface temperatures as high as 90°C on carbon fiber fin blades left inside a black car parked by the beach under strong summer sun!


Furthermore, there is an implanted logo on opposite sides of every pair of fins produced. The highly visible white color of the logo offers greater visibility and safety since a diver can be seen from any angle regardless of where they are facing.


Finally, the quality can be checked using a serial number / Trygons Genuine Sticker, which is also implanted in every pair of fins. We can track back each one of our fins to see when it was made, how it was made (batch number of materials etc.) and by which technician it was assembled / checked.



Thats our 12 meter long robot cnc. It has been converted to cut fabrics, and will be able to cut up to 100 fin pairs per program circle!


2) Efficiency: Minimizing losses is our primary target in any Trygons design. Whether it is a boat or a sled, we start by looking at the energy losses of previous designs. We then estimate the percentage and start figuring out how much of this could be retrieved. For stereo fins, we estimated energy losses to be roughly 90%! *. We saw lots of room for power profit here.


A typical diver produces an average constant force of 200 Newtons at the foot-pockets for maintaining a steady horizontal speed of 1 meter / second. This same speed can be achieved by a typical diver descending without fins and with 2 Kilograms (20 Newtons) of negative buoyancy. In other words, a typical diver needs to give 10 times more power to his fin to achieve the same result. This is a fast way of estimating the 10% efficiency.


The new foot-pocket / rails design has an enormous hydrodynamic advantage over previous designs. We found out that most of the energy losses resulted from the turbulent drag forces behind the foot-pocket and rails. Thus, with the help of “CAD - FEA” (Computer Aided Design - Finite Element Analysis) and lab tests, we gained 30% - 60% (high speeds) of the foot-pocket and rails turbulent energy losses. Design features, such as letters and walking strips that are standard features in other fins, have all been removed in this design.


The angle of  the carbon blade is 21.5 degrees, the angle of  the foot pocket with the  foot itself has an additional 2.5 degrees. So, the overall swimming angle is  24 degrees.


The difference is so obvious that even a recreational diver can feel it immediately in comparison with other fins! During the freediving negative buoyancy free fall, the speed of the diver is increased by approximately 40% compared with conventional fins. The same differences can be seen in dynamic pool freediving. In dynamic dives the diver needs significantly fewer strokes to reach the other end of the pool compared with conventional fins.


Another interesting result from our extensive testing was that we found a particular blade stiffness that was the best choice for 90% of divers. It didn’t seem to matter whether it was a 40 kg woman or a 90 kg man, as it seems that the actual torque to the muscles remains quite the same regardless of leg length. At the same time, the amplitude of the fining is very different, supporting this case even further. So, we decided to produce and recommend only one grade of blade stiffness, equivalent to "medium-soft" of previous fin models we produced. Besides, the parabolic shaped bending curve of our blades allows both soft and strong fining without power losses.



The new fin is distinctive and unique.


3) Comfort: Until now, powerful foot-pockets have had to be very hard and tight on the foot in order to function properly. This is a major difference between competition and recreational fins. We found a way to make the new fins comfortable like a beginners fin, but powerful like a competition model.


A hard non-elastic strap facilitates the transmission of leg power to the blade. This strap acts exactly where needed and nowhere else. The rest of the foot-pocket is made out of a very soft and flexible rubber giving it a very nice and comfortable feeling. Having a loose and flexible foot-pocket is also important for cold water diving as it does not restrict blood circulation.



4) Adjustability to style & needs: We cut off the rails from the foot-pocket in order to make them even softer and easier to replace as a separate part. We also came up with the ingenious strap. This strap can be made from a large choice of materials and is noticeably less elastic and energy absorbing than rubber. Now the blade feels like it’s bolted to the feet! By changing this strap, or even putting a tape over it, the diver can change the character of the fins a lot. The same pair of fins can be soft and comfortable for many hours of continuous swimming, and with a swift change they become a world-record tool! The strap has been designed to stay in position without being glued onto the fin. By pressing the upper rubber area of the foot-pocket to the inside, the strap can be pulled out or in!


We cut off the rails from the foot-pocket in order to make them even softer and easier to replace as a separate part.


5) Durability: Every new version we constructed was tested extensively in both the laboratory and the field. We know from experience that stereo-fins often get a very hard life. Over 50 different fins models were constructed and crash-tested before we were happy with the final product!



Our main fin testing machine. It uses a 3hp 3phase speed controlled motor. At its max speed ( 100 strokes/ 1 meter amplitude

per minute), it can brake a good fin instantly! At 60 strokes per minute, it wears a fin at a rate estimated 50 times faster than a

strong freediver. Fin development with this machine was shortened by years.


Lastly, and most importantly, the new foot-pocket plays no role in the blade bending. Until now, fins were using the foot-pocket rail stiffness to bend the blade. Fins were called 100% carbon, where typically most of their actual elasticity / hardness originated from the rubber foot-pocket rail. Because rubber wears much faster than glass or carbon fibers, that’s also why fins were loosing stiffness with time.



The new 3tons Trygons autoclave, dedicated for making the perfect blade.


We have cutoff the connection to the rail and made the rail separate, very soft and with a narrow profile. The rail piece is now only there for streamlining the flow and nothing more.


As a direct result, the blades for these new foot-pockets are significantly thicker and stiffer than before. The new fiber blades are made to do the whole job by themselves! We can now claim that these are the first ever REAL fiber reinforced fins. Over 90% of the swimming is now done with fibers (carbon or carbon/glass). Even our carbon / glass model is way better than any other “100% carbon” model! For the record, even our chosen strap material has an internal fiber lining.


We can now claim that those are the first ever REAL fiber reinforced fins.


6) Value for money: Making the best freediving equipment in the world is only half the challenge. The other half is to make it affordable and widely available. So, after using the best materials, machines and procedures available we had to find a way to lower the cost. To do that, we set-up a highly advanced production line: Robotic fiber cutting, PLC controlled resin infusion and curing and compressing for a start. Additionally, we acquired another 4 specially designed machines / tools, purposely designed to increase efficiency.


Carbon fiber, which is the main cost in producing these fins, is a widely used material at Trygons (we also produce carbon fiber boats)! By setting up annual contracts with suppliers and ordering large quantities, we managed to keep the price of materials to a minimum.


Carbon finer is harder and faster in recovery speed than fibreglass. As a result, RX fins are thinner and lighter than R2 because they use less material for the same stiffness. Although RX and R2 fins have the same exactly bending curve and stiffness , due to carbon  recovery speed,RX are slightly more efficient.

Main difference is , that RX fins are stressed less for the same work output. As a result, rx fins are expected to keep their output properties for a longer period. So, if you are a professional, using your fins in daily basis, then RX is the recommended fin for you. RX blades are proven to remain the same, even after many years of extensive swimming.Taking into consideration that most of the elasticity behavior of a blade comes from the outer layers, a more cost effective fin model has been introduced: "R2".

The R2 model has carbon fibers in the outer layers and fiberglass in the inner. With a small difference in output there is a huge difference in pricing!



Guaranteed 100% identical with the world record Trygons fins used by world-class athletes!