“We wanted a technical blade, to be used in quite challenging dives, still light on the legs. We have increased the length of the H2O by 10 cm compared to traditional blades, and have used differentiated fibers, which for us are only 100% Italian carbon, and thanks to the 29° angle the blade is very effective, but at the same time does not stress ankles”, comments Amedeo Marcelli, Seatec boss.

Among the spearfishing fins with carbon fiber blades, the Seatec H2O are extremely interesting, even though they do not seem to be very diffused on the market, at least if we refer to how much they are discussed on social media, such as Facebook. Most probably though, the Italian Company of Brescia is focused on practical and concrete actions on the product, more than social activities, and as AP we must sincerely admit that the new H2O are full of concrete solutions.

Exterior design

Extremely neat, with the blades having a rugged black surface  and the red writing “SEATEC H2O”, the well refined foot-pockets with light blue PVC insert, water rails of big dimensions and particular shape: the Seatec H2O are a product that transmits quality. The connection points of the foot-pocket to the blade, with 3 screws instead of only 2, are very neat .

The only two points that are not 100% neat are the matching of the rubber profiles of the blade with the longerons, as the latter remain slightly open, and the final profile of the blade, covered with residual rubber. Seatec points out that rubber is perfectly removed in the fins that are sold to public and that the cut of the profile is done very precisely with numerically controlled machines working on 5 axis.


The material of which the blades are made is a base of Pre-Preg UD 200/300 and balanced (meaning non Pre-Preg) 200, 100% Italian carbon fiber, with epoxy resin. The layers of the H2O are made with straight profile sheets, visible on the surface of the blade thanks to the reflexes of light, especially at the tip. Lamination and hardening process are brought foward using steel molds positioned in autoclave at 145°C and very high pressure (6 bar). The surface of the blades, as anticipated, is not smooth, just as we can find also on the Alemanni Speedy fins. Seatec has taken this solution from the animals of the sea, such as sharks, and has had confirmation of the positive effect of such characteristic from the tests done, which confirm the greater capacity of the blade to move water compared to a completely smooth surface one.

Dimensions and weight

Blades are extremely light, only 275 grams, even though water rails are quite big, but correctly designed to be very thin in the longitudinal section, so to be able to cut through the water easily. Their shape has a discontinuous height to avoid bends that would influence flexion of the blade and create a stop to the sliding: a simple and interesting solution. Length of water rails is measured equal to 39.5 cm, while height is mostly 1.3 cm, with a peak at almost the end of the blade (most important area to avoid lateral slip) to 1.4 cm.



The foot-pocket, size 42-44, weighs 860 grams, while the entire fin, with screw and plastic washers, weighs 1.10 Kg, a medium-high value determined by an important foot-pocket with its PVC insert.

Blades measured from the two holes for the screws to the tip of the blade are 67.5 cm long centrally and 70.5 cm long laterally, due to an almost dove tail profile. Such values position the H2O among the longest blades after Alemanny Speedy and GFT Alpha.

Thicknesses measured go from 0.55 mm at the tip of the blade, to 0.90 mm at mid blade, to 1.6 mm in front of the toes. Such values are quite low compared to other blades and confirm that the blade is soft (even though, evidently, final hardness depends on the manufaturing process, the carbon fiber and its orientation, and the resin).

The foot-pocket – blade angle is equal to 29°, a value much used on modern fins and that, Seatec comments, determines a greater preload, making the blade more reactive. Such solution, the 29°, is also used by C4 Mustang for example, but these reach 32° thanks to the 3° curve angle of the patented C4 foot-pocket.



The H2O are extremely flexible along all the length of the blade (we have received for the test the soft version, but the medium is also available). The flexion shows also a accentuated curve 10 cm from the tip of the blade, making an almost V shape, probably wanted by Seatec to help the restart from the bottom. It is also possible to see quite easily two lines indicating the layers , showing the strong reduction of thickness in such area.

Reactivity of the blades is very good, but seems to be a little lower than the best, such as Seac Motus and Pathos Abyss for example, even though it must be said that this aspect is quite proportional to the stiffness of the blades and does not necessarily indicate better performance in the water.


They are really something special, both for the quality of manufacturing, softness of the technopolymer, together with a great general structure given by the rigid insert in PVC, a unique solution, that has the double function of creating a rigid base for the foot and of transmitting the force directly to the blade, thanks to an excellent connection system between the two elements (foot-pocket and blade), insured by three instead of only two screws.


Moreover, while the two traditional screws under the toes are tightened in the classic way on a plastic base, the central greater screw under the foot is tightened in the PVC insert, which actually has a steel thread which ensures a much better and stronger connection.

As anticipated, the technopolymer, of one single type and hardness, is soft compared to competition (see for example the Delta One K-Reinforced foot-pocket of Salvimar Boomblast), with 40 Shore, long and thick (high) longerons, very flexible to avoid influencing flexibility of the blade, but still be able to direct water flow. Rigidity comes, in addition to the PVC insert, from the differentiated thicknesses of the technopolymer in different areas of the foot-pocket, in particular the instep which is thicker. No plastic clips are used to connect the longerons to the blade, but the connection still seems to be safe.

Available sizes of foot-pockets are: 40-42, 42-44, 44-46, 46-48, 48-50.

Click here to download the chart with complete technical data of the Seatec H2O.

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