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Omega’s deep sea oddity: The PloProf

By on 16 October 2013 in Watches

Omega’s deep sea oddity: The PloProf
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In the second in a series on cult favourites, the Watch Magazine’s Andrew Morgan considers the weirdly wonderful diving watch that has grown from unlovely marine tool to the embodiment of 1970s cool: the Omega Seamaster PloProf 600m

In the age of strangely shaped watches, one was shaped more strangely than all the others: the lopsided, red-buttoned slab of steel that was the Omega Seamaster “PloProf”. A watch that could only come from the 1970s, because of both its outlandish design and its role as a tool for professional divers in the greatest age of marine exploration. Jacques Cousteau himself wore it. This is tool-watch royalty.

The Compagnie Maritime d’Expertises (or COMEX) was founded in 1961 and pioneered much of the early work in deep sea diving and engineering. Operating in such dangerous conditions (the current rate for a saturation diver can be as much as £1,000 a day), the capability of a diver’s equipment can have mortal importance. So when, in 1967, COMEX commissioned a watch that could withstand dives of up to 600m deep, two of the world’s greatest watchmakers stepped up to the challenge.


While Rolex had its Sea-Dweller, a technological evolution of its game-changing Submariner that used a helium escape valve to prevent the crystal popping off during decompression, Omega took a different tack: brute force. After four years’ development, in 1970 the Seamaster Professional 600m was born. Dubbed the “PloProf” by the development team (meaning Plongeur Professionnel, or Professional Diver) the bizarre-looking watch was initially put to work by COMEX divers and Cousteau himself.

While Rolex used a helium escape valve, Omega chose to use brute force

COMEX eventually opted to stick with the Sea-Dweller and its helium escape valve, though the PloProf was successfully adopted by plenty of professional divers during its roughly decade-long production. As this ad attests.

Seamaster Professional PLoprof 1970)

Its failure with COMEX doesn’t mean, however, that the PloProf lacked the brains to match its brawn.

Take the dial. Where Rolex chose an acrylic crystal covering, Omega used chemically hardened mineral glass, a tougher material that allows reduced thickness and a flush fit. Beneath the crystal, the all-important minute hand was coloured a distinctive orange for quick reading, and pointed to a huge bezel embedded with luminous markers.


But that’s only the small stuff – the real innovation lay in the crown and that intriguing red button.

The knurled wheel that looks like a winding crown on the PloProf is in fact no such thing: it’s a nut that acts to pull in and seal the crown, which is in fact flat and square, sticking out when the tightening nut releases it. This served two purposes: the square shape prevents the crown unwinding, locking it flush with the case, and pulling it into the case provides a more uniform, reliable seal.


And the red button? This related to the bezel-locking system, ensuring that the traditional rotating bezel by which divers could compute their dive length stays secure while the dive is in progress. Where the traditional method, as used by Rolex and practically every diving watch under the sun, employs a bezel that’s ratcheted to only turn in one direction – in other words, it can only shorten your dive, rather than dangerously extend it – the PloProf’s doesn’t turn at all. That is, until the button is pushed, releasing the bezel lock and allowing it to be turned freely.


* * * *

But what of the PloProf now? The COMEX Sea-Dweller enjoys enviable fame, but that doesn’t diminish Omega’s achievement. It was still a fearsome performer for diving professionals in the great age of underwater discovery, and a piece whose pure, brawny functionality ironically lent it the esoteric design flourishes that make it so recognisable.

It was a fearsome performer in the great age of underwater discovery

Partly thanks to its short-lived existence and consequent rarity, an original PloProf commands a healthy asking price of around £4-5,000 – compared to a period Sea-Dweller, fair value for a trailblazing vintage diver. And there will always be those who argue that the Omega has more character than the Rolex anyway. It may be a bit of a brute, but it’s a loveable brute that became a legend in its own right – so much so, in fact, that Omega brought it back in 2009, this time going to 1,200 metres. But for the vintage collector, it’s those rare old PloProfs from the glory years of deep sea diving that remain hot property.



Andrew Morgan is editor of WF&Co’s luxury horological iPad publication, The Watch Magazine, which can be downloaded here.


Omega’s deep sea oddity: The PloProf

A look at the weirdly wonderful diving watch that has grown from unlovely marine tool to the embodiment of 1970s cool

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Andrew is a car and watch enthusiast as well as editor and writer at The Watch Magazine, the online watch magazine by Watchfinder. He packed in a successful career in civil engineering to pursue his passion for writing and horology and has never looked back. The fool.

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