HYT’s concept of watches with a fluid displaying the time in a capillary is original and a lot more complex than meets the eye. One of the problems that they had was that a coloured liquid tends to deposit colour on the walls of the capillary tube, which would of course defeat the purpose of the two immiscible liquids, one transparent, the other coloured. They had to design a capillary with a special coating that repels the colour. This alone took two years.
Another problem is thermal expansion. Just like any other material, a liquid expands and contracts with changes in temperature, and so a HYT watch would run fast or slow. To overcome this, they designed a thermal compensator.
The H3 presented at Baselworld in March 2015 was an incredibly complicated watch, and an advance on the original HYT concept because the liquid is not just used for the display, but also for powering the rotating hour rod. The H4 is a development of H1, and the changes are mainly linked to the case material, 3DTP carbon, based on carbon threads and also used in the aeronautical, sailing and automotive industries for its extreme rigidity. It provides a streaked look (similar to that seen in Panerai’s Carbotech). The strap is in another high-tech material, rubber and Nomex fibre, an aramid fibre used for racing drivers’ suits and helmets.
In terms of design, the H4 has a capillary inside the hour indications on the bezel (in the H1, the capillary was outside the numbers). The movement has been opened up by skeletonization and the elimination of the dial, so that you can see the gear train and part of the barrel. The sense of space is enhanced by the generous size, 51 mm diameter, 17.9 mm thick. A sapphire disc is anchored at 4 and 8 o’clock and holds the minute indicator, and the power reserve indicator at 3 o’clock. The two bellows at 6 o’clock, whose compression and expansion determines the movement of the liquids in the capillaries, are in even clearer view in the H4. The watch’s mechanism was, like the H2 collection, created by HYT in cooperation with APRP, Audemars Piguet Renaud & Papi, with coordination by Giulio Papi.
Sapphire caseback revealing the movement
The caseback has a chrome-plated metallized finish, so that it is reflective from the top, acting as a mirror to enhance the view of the movement. From the other side, it resembles a smoked glass, revealing the reverse side of the calibre. The movement is hand-wound, with bridges decorated with Côtes de Genève. It runs at 28,800 vph (4 Hertz), and has a power reserve of 65 hours.
Price and availability
The H4 Gotham is a 50-piece limited edition, price €77,000, CHF 77,000, US$ 79,000. It will be available from about June 2015. Reference 151-CB-03-RF-RN.