After receiving and analyzing the new extremely interesting Cetma Lotus bifins, we have finally had the pleasure to receive what is indisputably one of the best, if not the best, product of its kind on the market, the freediving monofin World Record holder with Alessia Zecchini, the Cetma Taras monofin. Alessia has conquered an amazing -123 meters, in 3’51”, at the 2023 AIDA Oceanquest in the Philippines. Zecchini and Keenan, his trainer and safety diver, have been a wonderful and at the same time tragic story of freediving.
Cetma Taras revolutions
The title might appear extreme, but when you put together three main technical innovations of the Cetma Taras monofin and analyse them, you understand the revolution that the Italian company has brought to market. The foot pocket, the blade and the overall design are the three main elements that we will analyze together.
Best freediving foot pocket
Natural rubber
The freediving foot pockets for monofins are definitely the ones made in natural rubber. In fact, differently from the ones for traditional fins which simply need to transfer a load, without deforming, these are designed to “collaborate” to the finning, becoming a real articulation. Cetma Composites has worked and tested many synthetic rubber solutions, but in the end there is no other option than natural rubber. In fact, only such material has the capacity to return most of the elastic force impressed during the finning action. The rear band works perfectly to improve energy transmission. Finally, the foot pocket becomes an active part of the fin to improve the entire efficiency in every kick.
Moulding process
The historical Eastern (Ukraine) and Russian producers, such as Rocketfins, Goldfins and Starfins, have for years designed natural rubber foot pockets, but the manufacturing process was artisanal, and so quality and performance varied a lot. This made all the fins, even of the same model, differ completely in performance. Cetma Composites has managed to design a natural rubber foot pocket manufactured through a moulding process.
Such solution has led to foot pockets of perfectly repeatable high quality and performance. Even the tip of the foot pocket, which participates to the finning action, is a concentrate of engineering, which has both mechanical functions on the kick and physical functions as it collaborates with the balancing of the blade. Such positive result has helped in the testing phases, as the foot pockets could be well compared and the performance of the fins was analyzed with the foot pocket always offering the same performance. This led also to a great improvement in the design of the blade.
Monofin blade
It is true that the Cetma Taras bifins are also excellent record holders, and the design of the base of the foot pocket is the same as the monofin. Still, the design of a monofin blade entails various problems that are not present on bifins. The width of a monofin, be it a swimming monofin or a freediving monofin, reaches high values. For example, the Cetma Taras monofin has a maximum width of 69 cm, compared to average values of bifins of 20 cm.
Correct flexion along 3 directions
A freediving monofins blade needs to control the flexion along three axis and not only one like bifins blades. Such axis are the longitudinal one (0°), the transversal one to the length of the blade (90°), and the axis at 45°, meaning the axis between the first two. Cetma Composites has worked with a finite elements software, once more basing all its R&D on high level engineering studies, as done for all its diving fins.
90° axis
The main negative deformation that traditional monofins have is that they bend taking the shape of a spoon. Without the right control of the deformation, the blade not only bends, as it is correct, along the longitudinal axis, but also transversally. Such deformation determines a good part of the water flow to exit the blade laterally, losing a lot of power. To avoid such transversal bending of the blades, Cetma Composites has worked to design a blade where the layers of carbon fiber manage to control the transversal deformation, still insuring best performance given to the longitudinal deformation and great elastic return.
45° axis
Another deformation which needs to be limited is the one along the 45° axis. This one is mainly generated by the extensions of the two lateral tips of the blade, where the water rails end. The high extension of the blade along the 45° axis, in fact, determines an excessive bending of the blade. Once more, Cetma has worked to design a blade where the layers of carbon fiber with their orientation limit the bending along the 45° axis on both sides.
The look and feel of the blade
The incredible advanced design of the blade of the Cetma Taras freediving monofin determines a visible special look. In fact, using the correct angle of the light illuminating the surface of the blade, you can see, just as in the photo below, a series of bell shaped curves. The orientation of the internal layers is not visible of course, but the different thickness of the blades can not only be seen, but also felt with the hands touching the superior surface.
Perfect balance
There is finally another great revolution obtained by Cetma, the perfect balance of the blade with the freediver’s body. This is needed as during the dive the freediver is in the gliding phase most of the time. After the kick, in fact, the diver utilizes the thrust generated to move meters without additional movements of the legs and ankles, meaning no waste of energy and oxygen.
In this phase, the body and monofin need to be perfectly balanced, so the freediver does not need to act and change his position to keep a smooth straight line. To obtain such solution, one element is the presence of extended tips of the foot pocket, both in the upper and inferior part of the blade. Additionally, the lateral extensions of natural rubber present from the foot pocket for 45 cm all along the blade profiles, also called wings, have themselves the function of keeping monofin and freediver perfectly balanced helping fluid dynamics.
Such wings have also the additional detail of some holes present along them to generate a turbulence which actually reduces resistance to the glide. Cetma Composites has studied this phenomenon starting from golf balls. The sensation is that of easy gliding.
Results in the performance
All the above revolutions permit finally to have a very light, balanced and efficient freediving monofin. The force needed for the optimum kick is the same in the positive and negative phases. The design of the Cetma Taras monofin also permits to utilize during the finning much more the ankles compared to the entire legs. Such aspect, of using much smaller muscles, determines an important reduction in energy and oxygen consumption, to the benefit of the entire dive. The natural rubber foot pocket cancels any delay between the kick and the reaction of the blade.
Customization
Blade hardness
The Cetma Taras freediving monofin can be extensively personalized. The blade stiffness goes from 1 (softer) to 8 (harder). It is true though that for freediving the correct stiffnesses are 1, 1.5, 2 and 3. Above, the hardness are thought for finswimming (CMAS homologated).
Foot pocket shape
In addition to the choice of the hardness of the blade, the foot pocket can be customized (+50€). The sizes available are 35-36, 37-38, 39-40, 41-42, 43-45. Such process is key and works as follows. Normally the moulding of the natural rubber for foot pockets consists of the material being injected and then vulcanized in an unreversible process. For the customized foot pockets the vulcanization is processed only partially. After that, the foot pocket is shaped using special machines similar to the ones of a shoemaker. In such a way, the freediver has the perfect foot pockets for his feet and also the left and right design is made.
Some measures
The Cetma Taras freediving monofin has a maximum width of 69 cm between the water rails. The total length of the blade starting between the foot pockets, is 52 cm. The lateral wings are 45 cm long, while the water rails are only 16 cm long and have a variable height of maximum 2.2 cm. The total weight of our Cetma Taras monofin, stiffness 2 – SM (Soft-Medium), foot pocket size 41-42, we have weighed, is 2.435 kg.
