Composite materials.

Composite materials consist of two materials: resin (matrix) and fibres (reinforcement) drowned in the resin. In order to create a composite with an excellent mechanical performance, the percentage of the resin should be as close as possible to 40%, being the optimum value. In these cases the term advanced composites can be used.
How can we understand if a carbon blade is made from an advanced composite, that is with a low quantity of resin? The weight of the carbon part can be a hint. On equal terms (hardness) the blade with the composite part being the lightest, therefore with less resin and more fibres, it will have greater mechanical qualities and characteristics.
By comparing the weights of two blades to see which is the lightest, it is important to remember to also take into consideration the dimensions of the blade and the weight of the water rails. Larger blades and larger water rails are much heavier.
Due to its blades C4 uses 40% of resin therefore when we speak of our products we also speak of advanced composites.

Molding system.

To create an excellent advanced composite, therefore with low percentages of resin and high percentages of fibre, it is vital to have a molding system that strongly compresses the layers of fibres between them. If the fibre layers are not compressed due to insufficient specific pressure, unavoidably the composite will contain more resin interposed between the layers of fibres. This excess resin will inevitably degenerate the mechanical characteristics of the composite.
A high specific pressure molding system is necessary so that the fibres of the various layers are in direct contact, not separated by an intermediate layer of only resin. Layers of fibre in direct contact transmit stress without internal dispersion and this makes the advanced composites the materials with the best weight/resistance ratio that man knows.
By compressing the resin with strength and low percentages of resin, the very best energy transmission is achieved between one layer and the other of fibres, inevitable if the very best mechanical characteristics are sought after such as elasticity, reactivity and resistance.
To mold C4 use a high specific pressure so that the layers of fibre are in contact with one another. The best values of specific pressure depend on the thickness of the tissues used and the quantity. These values are approximately 0.6 -1.2 atm for every layer of fibre.
Molding systems that only use the strength of the vacuum, as many of our competitors do, are insufficient to create good compression. This is because specific pressure that can be achieved with a vacuum is approximately 0.9 atm. This value should be divided by the number of layers to be compressed. A carbon blade has approximately 6-8-10 layers of fibre, the value of compression of the layers of fibre achieved with the vacuum is therefore a little less more than 0.1 atm for each layer, a value that is too low for good inter laminar adhesion. Therefore in the forges made with the vacuum technique, it is important to use a lot of resin to connect the layers, with decomposition of the mechanical performance and an increase in weight of the forge. C4 does not do this.
C4 only moulds in a high pressure and high temperature, this allows for the very best characteristics of the epoxy resins used in the composite. After moulding at a high temperature the C4 blades undergo another after-baking heat treatment for 15 hours at 70°C, a treatment that raises the mechanical characteristics of our composite to the highest possible values.
Figure 1 illustrates a classical moulding for prepreg in autoclaves in which the specific pressures recommended are visible.

Carbon fibre.

C4 only uses expensive and prestigious T700 fibre by Toray, the international leading manufacturer of carbon fibre. According to figures provided by the manufacturer of the fibre (table A) we can see how the T700 yarn is 40% more resistant compared with the T300 yarn commonly used by our competitors. The greater resistance of T700 makes our blades 40% more resistant compared with similar blades made from T300: this is not just our opinion but it is proved by the fibre manufacturers.
Toray, the fibre manufacturer, indicates (table B) how the technical characteristics of carbon do not change as the number of K’s vary (number of filaments in each single tow). A low K number indicates the technical possibility of creating fabrics of a low grammage and high conformation, something that helps in the lamination of difficult 3D surfaces but is not at all useful in making blades for fins.
Vice versa, a fabric with a high number of intersections between the weft and the texture, typical of T300 fabrics with thin yarns, dramatically increases the dissipation of internal energy during bending due to the large number of intersections of the fibres. Each intersection absorbs energy, the more there are, the greater the losses.
Each single C4 blade is numbered and indicates the type of fibre used in an indelible form. This assures our customers that are blades are 100% made from T700 carbon yarn.

Fins: lamination, elastic performance and resistance.

Fins should not soften energy, they should take it to the highest possible level.
In order to achieve this, C4 uses a lamination of the longitudinal fibre so as to connect the energy source (the foot) directly with the portion assigned to transform energy into water movements (the blade). The cross fibres present in the fabrics are used to provide the blade with necessary solidity for the use that it is destined for, including mistreatment, something that is always possible. The C4 blades have been made for 20 years with a mixed lamination of fabrics and one-way fabrics. The amounts of fabrics and one-way fabrics depend on the models and level of rigidity desired.
A lamination that includes fibres at 45° compared with the centre line of the blade, neutralises the majority of the elastic performance as it does not use the main characteristic of the fibre, that is to say its resistance to pressure subject to strength. At 45° compared with the direction of the strength, they do not connect the stress points therefore they work partially.


Everything has a beginning, including breakage of composite blades and this begins when a yarn that forms the fabric breaks. The larger the yarns that form the fabric, the greater is the resistance of the blades to the start of the fracture. Blades made with large yarn fabrics such as C4, require stress values that are much higher than the blades made using thin yarns for the start of breakage. These values of resistance to the start of breakage are directly proportional to the size of the yarn. The thick yarn used by C4 is 3.5 times larger compared with the thin yarns of our competitors and this is added to the effect of greater resistance of T700 (+40%) resulting in our blades having a theoretical resistance to the start of breakage five times higher compared with corresponding blades made in T300 carbon with thin yarns.

Fins angle.

The bending angle of the C4 blades is currently 29°. This extremely important factor results in the homogeneity of the backward and forward fin movements that, with smaller angles, cannot be achieved. We started to make carbon blades with an angle of 17° in 1990 and then we moved on to 20°, then 22°, then 25° and now 29°. We are very well aware of the effect o the angle on the fin movement, our history proves that we have been studying this since 1990. We went further. Our Mustang anatomical shoes, that we use on our main models, are preformed to 3°. Therefore we currently have an angle between the foot and the blade for these fins of 32°.
All of theC4 blades are angled but do not have a clear bend, but a wide curve. We were the first in 1993 to use this wide shape. This wide curve reduces any non-uniformity in shape, resulting in a homogeneous bending of the entire blade, from the heel to the tip and not only of the front portion. In this way breakages are reduced as stress is divided over a larger portion and increases elastic performance.

Water rails.

In 1993 C4 invested the water rails, changing fin movements underwater. They have a dual function: to make the fin move as much water as possible and to stabilise the fin, preventing twists and unaligned movements. “It is just like moving along two tracks”: these are the words used by somebody that has used these fins, proving how the water rails eliminate uncontrolled twisting in scuba diving. It is easy to understand how higher water rails stabilise the pins even more and move more water.
In 1993 our first water rails had a constant profile 10mm high, we then changed them to 12mm, then 14mm and finally reached the VGR models (Variable Geometry Rails) that have introduced a new and highly efficient concept of water management on the blades.
The fins work by accelerating water from the foot to the tip of the blade: this creates a reaction that provides movement to the scuba diver. The water that accelerates is of different speeds according to the various areas of the fins and considering that it is a liquid, therefore incompressible, as speed increases it generates a reduction in the section involved. This results in observing fluid threads with a larger section immediately after the foot area (high water rails), gradually reducing down to the minimum section (low water rails) at the end of the blade.
These are the origins of studies for the creation of our VGR and EVO water rails (C4 patent) of a variable shape. Their shape follows the variations in the volume of water worked by the fins, section by section. This improves the hydrodynamic efficiency of the fins with impossible results .
During fin movements, the water rails deform with waves on the opposite side to bending, this occurs with all types of water rails by all manufacturers. This is a negative phenomenon and it depends on the height of the water rails. The higher they are, the larger the waves, but the amount of water worked and the benefits provided will also be greater. As always, the final result is the difference between the positive and negative contribution, technically this is called performance. Our studies have shown how the positive contribution of water worked thanks to the water rails is much higher than the losses in turbulence due to deformation to waves, the problem basically does not exist.

How can I calculate the length of the bands for the spearguns?

A) calculation of the length of the band for spearguns with head:
1 – deduct the length of the steel/dyneema wishbone used from the measurement of the length measured of the head/band elevator to the notch/fixing fin of the shaft (eg. 99cm) (eg. 99 – 5 = 94cm).

2 – divide the result (eg: 94cm) by the stretch factor desired for the chosen band. For the C4 Hi-Speed bands of any diameter, the factor of extension recommended varies between 3.5 and 4.0 (eg: 94 : 3.7 = 25.40cm).

3 – the value achieved (eg: 25.40cm) is the length of a ban measured from one clench to another.

B) calculation of the length of the band for spearguns with loop ( circular band ):
1+2+3 – calculate everything as above for spearguns with muzzle, points 1+2+3.

4 – the length achieved must be multiplied by two (eg: 25,.0 x 2 = 50.80cm) as there are two moving arms.

5 – the measurement of the inactive course of the band should be added to this value (eg: 50.80cm), required to create movement to the muzzle. Due to friction created by the extremely heavy specific pressure created between this section of the band and the surface of the speargun, where they come into contact, mutual sliding cannot occur. This is a portion of the band that remains inactive. This measurement should be added to the length, as indicated in point 4, and it depends on the shape of the head of the speargun, the larger it is, the longer this measurement will be.

For our spearguns with loops, add: Urukay +5,0cm - Joker +4,5cm Graphite +4.0cm (eg: Graphite99 – 50.80 + 4.0 = 54.30cm length of the loop from one constrictor knot to another)

For multi-band spearguns, remember that the measurement of point 1 may vary for each couple or loop according to the notch/fixing fin considered.


Which shaft and band measurements are recommended for the C4 spearguns?

Mr.DARK 119
aste/shafts : 7x1600
BLACKBULL 17,5x300 + 16x270 -- 16x295 + 16x270

Mr.DARK 104
aste/shafts : 7x1400
BLACKBULL 17,5x270 + 16x240 -- 16x270 + 16x240

Mr.DARK 94
aste/shafts : 6,5 x 1300
BLACKBULL 17,5x240 -- 16x240 + 16x220

Mr.DARK 79
aste/shafts : 6,5 x 1150
BLACKBULL 17,5x200 -- 16x190

Mr.DARK 61
aste/shafts : 6,25 x 1000
BLACKBULL 17,5x160 - 16x150


aste/shafts : 6,75 x 1700 - 7,0 x 1600
BLACKBULL ( circolare lungo/long loop) 17,5x780 - 16x730 - 14x670
BLACKBULL ( circolare corto/short loop ) 17,5x730 - 16x670 - 14x630


aste/shafts : 6,5 x 1600 - 6,75 x 1600 - 7,0 x 1500
BLACKBULL ( circolare lungo/long loop ) 17,5x700 - 16x660 - 14x630
BLACKBULL ( circolare corto/short loop ) 16x640 - 14x610


aste/shafts : 6,5 x 1400 - 6,75 x 1300
BLACKBULL ( circolare lungo/long loop ) 17,5x700 - 16x550 - 14x510
BLACKBULL ( circolare corto/short loop ) 16x490 - 14x460


aste/shafts : 6,25 x 1200 - 6,5 x 1150
BLACKBULL ( circolare lungo/long loop ) 17,5x500 - 16x460 - 14x430
BLACKBULL ( circolare corto/short loop ) 16x410 - 14x380

Mr.Carbon/Mr.Iron 119 PS

aste/shafts : 6,25 x 1600 - 6,5 x 1600 - 6,75 x 1500
BLACKBULL 17,5x290 - 16x280

Mr.Carbon/Mr.Iron 104 PS

aste/shafts : 6,25 x 1500 - 6,5 x 1400 - 6,75 x 1300
BLACKBULL 17,5x270 - 16x260

Mr.Carbon/Mr.Iron 94 PS

aste/shafts : 6,25 x 1300 - 6,5 x 1300
BLACKBULL 17,5x250 - 16x240

Mr.Carbon/Mr.Iron 79 PS

aste/shafts : 6 x 1150 - 6,25 x 1150 - 6,5 x 1100
BLACKBULL 17,5x230 - 16x220

Mr.Carbon/Mr.Iron 61 PS

aste/shafts : 6 x 1000 - 6,25 x 1000
BLACKBULL 16x170 - 14x160


aste/shafts : 7,0 x 1700 - 7,5 x 1700 - 8 x 1600
BLACKBULL ( triplo ela/triple bands ) 16x720 + 16x700 + 16x680
BLACKBULL ( doppio ela/double bands ) 17,5x730 + 17,5x700


aste/shafts : 7,0 x 1500 - 7,5 x 1500 - 8 x 1400
BLACKBULL ( triplo ela/triple bands ) 16x640 + 16x620 + 16x600
BLACKBULL ( doppio ela/double bands ) 17,5x640 + 17,5x620


aste/shafts : 7,0 x 1300 - 7,5 x 1300
BLACKBULL ( triplo ela/triple bands ) 16x540 + 16x510 + 16x480
BLACKBULL ( doppio ela/double bands ) 17,5x540 + 17,5x510


How to replace the water rails.

Remember that good gluing cannot be performed if the surfaces are contaminated by anything and/or material, gluing of the water rails should be performed according to the following procedure:
a) pass sand paper over the gluing areas, over the blade and over the rubber profile, cleaning with extreme care.
b) place a layer of cyanoacrylate glue (this is the best glue for rubber)
c) place the water rails on the blade, pressing down the glue lightly (using two planks of wood and clamps for example)
d) wait until it dries completely before removing the planks or other pieces used for gluing
e) wait at least 2 hours before bending the blades.


How to regulate the grip of the C4 spearguns.


Suggestions to improve precision of the C4 spearguns

Some parameters affect the level of precision of our spearguns. If there is no precision or the level of precision is inadequate, it is always best to check it.

For our spearguns without any kind of bar guide (single shell, Mr.Carbon/MR.Iron up until 2012), the best conditions for precision are achieved using a shaft with traditional notches (no fins) and nose cones with straight drive, like the ones whose coupling occurs through the use of a metal cable or dynema (no nose cones made from shaped/bent steel).

Our spearguns are fitted with a shaft guide (Urukay, Joker) or Shaft Slider (Graphite, Mr.Carbon/Mr Iron series since 2013) and they work in the best possible way with any kind of shaft, while the straight drive nose cones are always recommended.

Correct balancing of any kind of speargun is achieved when, with the gun loaded and with the handle bar laid to rest on an open palm, the tip of the shaft falls downwards at a speed of approximately 3-4 fingers per second (5.7cm). In water this is much easier to check.

For models fitted with an adjustable grip, pay special attention to the type and to the thickness of the mobile element of the grip. Out of the two standard versions provided, the narrower version provides greater aiming precision. Its regulation must be performed making sure that the last phalanges of the index finger rest on the trigger. If it has a regulation with less washers, due to the sensitivity of the trigger, the aim will definitely be less accurate.

It is possible to correct setting of the aim if it is too high/low, by acting on the number of washers of thickness of the grip. For example, if the aim is too high, add one or two washers to the upper screw, vice versa if the aim is low. Here is a link illustrating the regulation possibilities:

Remember that one washer should be removed, passing from summer gloves to winter ones and vice versa. As a general indication, normally a hand that wears L size gloves (span opening of approximately 20-21cm) has an excellent level of regulation with 6 washers with 3mm gloves and 7 washers for light summer gloves.

Obviously, the shaft should be substantially straight. To check this, once it has been detached from the heaving line or nylon and after having blocked the barb with a piece of adhesive tape, it should be rotated vertically on the tip. Any possible pleats or imperfections to the shaft will be clearly visible.


How to pass the heaving lines through the C4 spearguns.

How to pass the heaving lines through the URUKAY speargun