En el foro de watchuseek aparece esta interesante descripción acerca del plexi del Amphibia:
The Amphibia Design Approach. The two designers, Mikhail Novikov and Vera Belova, examined the existing dive watches on the market and noticed that the design approaches were somewhat in wanting.
Basically they were using brute strength to counteract against water pressure, on a piece-meal basis. They rejected all these designs and came up with a most elegant, integrated technical solution which we shall examine in further detail.
The fundamental concept of the Amphibia design is not to use brute strength to fight water pressure, but instead utilizes water pressure to enhance water resistance.
Crystal. It goes without saying that dive watches have comparatively thick and strong crystals, and dome crystals have the added benefits of being stronger. Novikov and Belova elected to use acrylic crystal, conventionally fitted into the front of the watch. What we call acrylic is actually a transparent thermoplastic polymer, technically known as poly(methyl methacrylate), PMMA for short, better known under its propriety names Lucite, Plexiglass, and Perspex. The combibation of PMMA material and dome shape creates an interesting characteristic: while the dome shape can withstand significant pressure load on the convex - external - side, the slight flexibility also allows it to deform minutely, increasing its diameter when a pressure load is applied.
The Amphibia crystal profile - thickness, and both internal and external curves - was carefully calculated with respect to the mechanical characteristics of PMMA. In actual production each crystal needs to be individually machined to a high level of precision, so that it can fit into the watch case tightly, to effect the first phase of water resistance. When submerged, the increasing water pressure will flatten the crystal, making its circumference minutely greater along the way, which increases the effectiveness of the seal between the crystal and the watch case.
An added consideration is that, at a depth of 200m, water pressure reaches 20kg per square centimetre, this makes the crystal pushed in by about 0.5mm. During the design phase of the crystal profile, special care was given to allow for sufficient clearance, so that the inside surface of the crystal would not hit the hands mechanism.
Resumiendo, los diseñadores del reloj pensaron que los relojes para submarinismo que había en el mercado, mientras se estaba diseñando su reloj, eran auténticos "tochos" de "fuerza bruta". Así que idearon un reloj que en vez de luchar contra la presión del agua, se aprovechara de ella para ser más estanco. Para ello pensaron en aprovechar las propiedades flexibles del plástico del plexi para que con la presión se aproximase más a la caja. Diseñaron cuidadosamente las curvas internas y externas del plexi para que se aproximara más en los bordes a la caja y para que el centro del mismo no se topase con las agujas al irse incrementando la presión externa.
Recomiendo leer el post entero:
http://forums.watchuseek.com/f54/vo...gy-491757.html#/forumsite/20758/topics/491757
En cuanto al Vostok Komandirskie, su diseño sólo permite ser resistente al agua para salpicaduras, lluvia, lavado de manos... El sumergible de verdad es el Amphibia, por lo que no te recomiendo para nada que te bañes con él. Me refiero al Komandirskie clásico.