4 revolutions in one fin
Fluyd dynamics in the C4 S-990
It all starts from the amazing new C4 200 footpocket, with a very compact design and the extremely special connection of the blade under the foot. On the fluyd dynamic side, this permits, just like the rear wing of a F1, to have a much cleaner flow of fluyd. So, all along the blade the water flow has no turbulence and obtains an extremely higher efficiency. This is possible as the water flow passes between the foot pocket and the blade. So the turbolences generated by the foot-pocket and moving on the blade surface are extremely reduced. The consequence is evidently a much lower effort by the diver for the same thrust. In addition, the shortened blades under the foot result in a further reduction of the hydrodynamic resistance of the area, allowing easy rotations of the feet during kicking, with sensation of great agility.
Biomechanics revolutionized with the C4 S-990
The position of the blade versus the footpocket
In line with the aim of reducing the effort by the spearo throught the maximum efficiency is also the position of the blade. The area where the force generated by the diver can be applied during the kick is key. The best solution to exercise the force from the foot to the blade is starting from the metatarsus. This is due to the fact that the human skeleton has in the area under the metatarsus its maximum power transmission. And this is what the geometry of the C4 200 footpocket generates with the attachment of the blade under the foot instead of on its tip. This permits to have a better balanced back and forth stride for good muscle performance. Also, the new geometry allows the diver to naturally keep a straight position, aligned with the direction of movement. This determines a much better water penetration.
Materials of the C4 200 footpocket
The C4 200 footpockets are manufactured with two distinct materials. A soft, thin and ultra resistant TPE (thermoplastic elastomer) is over-moulded on a rigid sole made in polypropilene. The upper material is softer (65 ShA) for sizes 36/37, 38/39 and 40/41 and slightly stiffer (74 ShA) for sizes 41/42, 42/43, 43 / 44 and 44/45. This guarantees the best comfort and performance. The C4 200 footpocket has 3° of inclination to perfectly adapt to the curvature of the foot.
Weight reduction
C4 200 the lightest footpocket on the market
Materials and lamination of the S-990 blades
The carbon fiber blades of the C4 S-990 are offered in 3 different hardnesses: Soft (25), Medium (30) and Hard (40). C4 indicates though a chart on its website the suggested hardness depending on the weight and height of the spearfisherman, and the type of use.
The guarantee of extreme resistance to heavy load and fatigue of the blades fo the C4 S-990 has been verified by testing them with a special machine. This has been specifically designed by the C4 technicians to produce repeated kicking cycles with 3 times the strength of a normal diver. 1.6 million cycles have been applied to the C4 S-990 fins to deliberate the quality and resistance. In addition, over 18 months of testing have been brought forward by an international team of C4 divers. These are: Giacomo Cubeddu, Andrea Calvino, Andrea Fazzolari, Luc Pillon, Giannis Pitias, Marco Rodo, Mariano Satta, Stelios Velikis, John Lopez, Gian Franco Loi, Stefano Oggioni, Ahmed Ben Salah, Fabien Renau, Marco Bardi and Eric Demontis.
Force transmission and ergonomic insoles
The C4 200 footpocket is designed to adhere to the entire foot. The idea is to transmit the force not in a single area, like many footpockets do reinforcing the are of the instep, but through the entire surface. To additionally improve this solution, together with an amazing comfort, C4 has designed ergonomic insoles. These are specifically made with materials adapt to the sea. Thanks to the asymmetrical shape the comfort increases, the planar shape of the shoes under the foot arch is greatly improved. All this thanks to the elimination of the void and thus increasing the control of kicking and optimising the propulsive force. The empy areas between the foot and the footpocket are filled and even the water sacks are so eliminated. Cold water flow is si minimized, thus keeping warmer the foot in Winter and reducing the risk of cramps.
Water rails with O.P.S. technology
Material of the water rails
3D shaped water rails are applied on the blades by the over-moulding technique. This has been developed by C4 specifically for the blades of the 200 series. Such process avoids any separation that can occur on glued water rails. Also, the O.P.S. (Over-moulding Protection System) of the water rails protects the blade from impact and damage.
The plastic polymer used to manufacture the water rails maintains elasticity four times more over time. The first portion of the water rail close to the foot protects the blade without overloading and limiting its elasticity. Progressively, the height of the water rails increases becoming an effective guide for the fluid threads, thus preventing load drops and skidding. The additional anti-skidding effect is obtained by the dovetail tip of the blades.
