The Cetma Mantra CWT Competition are part of the performance line by the Italian company, which includes the amazing Taras and the Lotus Carbon, Champion and Vice-Champion resepctively in the 2024 Best Choice by Apneapassion in the freediving fins category. Honestly, Cetma Composites is today practically unbeatable in the competitive freediving sector. The Mantra CWT Competition, as name indicates, have been designed for constant weight, but work great also in Dynamic apnea.
The Mantra CWT Competition has an optimized stiffness distribution to limit fatigue on the calf and tibia muscles, while the reduced bending angle of 27° (compared to 33° of the standard Mantra) ensures perfect posture during descent and ascent along the rope. It also performs well in dynamic disciplines, especially for athletes who prefer longer blades.
Dynamic Resonance System
The Dynamic Resonance System (DRS) is an innovative technology developed exclusively by CETMA Composites to enhance the performance of the MANTRA fin blades. This system is engineered to allow the blade to resonate within a specific range of finning frequencies, thereby optimizing propulsion efficiency.
Resonance is a physical phenomenon where a structure, when subjected to a force at its natural frequency, exhibits increased amplitude of vibrations with minimal damping. By meticulously designing the distribution of stiffness and mass, CETMA Composites has “tuned” the MANTRA blades to align their natural frequencies with common finning frequencies. This alignment enables the blades to enter resonance during use, resulting in significantly enhanced propulsion with reduced effort.
The development of the DRS involved advanced engineering techniques, including modal analysis performed with a laser Doppler vibrometer (LDV). This analysis was crucial in determining the optimal mass and stiffness distribution across the blade, ensuring that the resonance effect is effectively harnessed during finning.
In practical terms, divers using fins equipped with the DRS experience lower muscular fatigue and greater propulsion efficiency, as the fins work in harmony with the natural dynamics of finning. This technology represents a significant advancement in fin design, offering divers improved performance and comfort.
Water rails
The water rails are in silicone and have a variable height design for best performance. Additionally to all other fins on the market, not only do the water rails act with a greater height at the tip of the blade, but they also connect with an increased height also on the side of the S-Wing footpocket. The latter, in fact, has a special design with a flow channels to direct the water since the tip of the footpocket all along the blade. This improves water flow, reduces turbulences and increases the the quantity of water sliding on the blade. The result is a reduced friction, better thrust and efficiency at every kick.
Dimensions
The Cetma Composites Mantra CWT Competition fins are meticulously crafted for constant weight freediving, emphasizing both performance and diver comfort. The dimensions measured by Apneapassion are:
- Blade Length: Approximately 70 cm (27.6 inches) from the bending angle.
- Blade Width: Approximately 19.5 cm (7.7 inches).
- Blade Angle: 27 degrees.
These dimensions are optimized to minimize fatigue on the calf and tibia muscles, allowing divers to maintain an ideal posture during both descent and ascent.
Weight
The measures by Apneapassion indicate a total weight of the Cetma Mantra CWT competition, with 43-44 footpocket, of 910 grams. The blade, very light, has been measured 295 grams. The construction from 100% IM7 carbon fiber makes this blade very lightweight, enhancing propulsion efficiency and reducing diver fatigue.
Stiffness
Differently from the Cetma Mantra, which are offered in 4 different stiffnesses, Extra Soft, Soft, Medium e Hard, the Cetma Mantra CWT Competition have two stiffnesses, Soft and Medium. Such values are optimized to minimize fatigue on calf and tibia muscles during deep dives, but also Dynamic apnea in the pool. Cetma COmposites suggest the S blade for freedivers weight 70 kg or less, and the M for above.
Recommended finning techniques
To leverage the DRS, freedivers should adopt a finning style with a frequency that aligns with the blades’ natural resonance. This synchronization maximizes thrust while minimizing energy expenditure. Of course the Cetma Mantra CWT Competition are designed so that the finning rhythm optimized to match the resonance frequency is a wide range to make it easy to reach an optimal finning period.
Utilizing a flutter kick with controlled, moderate amplitude is effective. The blade’s design supports efficient energy transfer, making excessive force unnecessary. Maintaining a streamlined body position complements the fins’ design, reducing drag and enhancing overall efficiency. In such sense, the reduced 27° angle compared to the standard Mantra, permits naturally a better positioning of the body and a more efficient water penetration. On the other hand, surface transfers are more efficient with the 33° angle.
