OceanicTime Archives



Good old fashioned maths and physics meets rugged modernity! 

DELMA gives its longest serving diver’s model, the iconic Shell Star a new decompression feature thanks to some old world maths and physics. 

Yes, the functionality of the new Shell Star Decompression Timer is based on research of Swiss diving, pioneers Hannes Keller and Albert Bühlmann from 1950s and 60s.

Both were former students of the University of Zurich; their combined expertise in mathematics, physics and diving drove them to conduct groundbreaking research in the field of diving. 

Recognizing the impact of altitude on decompression, they co-developed tables with specific gas mixtures for different elevations.

Bühlmann focused on identifying the correct combination of gases while Keller carried out experimental dives in order to test their theories. 

The resulting tables enabled safe decent at sea level as well as in mountainous terrain and were even adopted by the Swiss military in 1972.

Even today, they are considered to be the most intuitive of their kind, uniquely taking into account the need for multiple decompression stops for deeper and longer dives. 

The Delma Shell Star Decompression Timer is optimized for diving with air breathing at 0-700 meters above sea level. The diver uses the unidirectional bezel to time his dive.

The vertical scale on the dial at 12 o‘clock corresponds to their dive depth in meters or feet. 

It enables the diver to clearly see if their dive is within the no-decompression limit (NDL) where no decompression is required or whether decompression stops are necessary.

The NDL time is reflected by the white markings on the rings, while the amount of decompression stops and their duration are shown by the numbers. Unlike other comparable timepieces, DELMA’s Shell Star Decompression Timer utilizes Keller and Bühlmann’s research to clearly display when multiple decompression stops are needed for dives at sea level and beyond.

In keeping with its technical diving functionality, the Decompression Timer features a helium escape valve and a water resistance to 500 m / 1650 ft. 

It is offered with a black, blue or orange unidirectional bezel with either a stainless steel bracelet or rubber strap.

All models are automatic and contain a SW200 movement with date and DELMA customized rotor. Key historical characteristics include a spade central seconds hand, the railway track and orange and white indexes.

The stainless steel case is sealed with a transparent case back revealing the intricate movement. Durability and strength have always been essential to the Shell Star and this new release is faithful to the collection. 

The bold decompression timer functionality completes a unique diving tool worthy of attention.

Thoughts? There are a couple of these decompression diver’s watches with their throwback timing tables; MIDO, CW and now this. But of the three, the new Shell Star Decompression Timer would appear to have the better diving credentials thanks to its rugged build. 

I prefer a more toolish watch, so it would be my choice of the three and I’d take the blue dial with blue rubber, but how about you? CW (which is sold out anyway) MIDO or this new DELMA?


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