Project Description

Zenith Defy Professional 600 metre Ref. A3646 £SOLD

Think Zenith. Think El Primero. The world’s first automatic Chronograph. No this Zenith is much much rarer than the albeit amazing EP. This is the Zenith Defy Plongeur 600m Ref. A3646. And they only produced 200 of these with the white/cream dial from 1969 to 1971.

This watch has had a life and bears a few scars as a result. But nothing horrible.

It is unpolished, the bi directional bakelite bezel still turns nicely, it still has the original Guy Freres steel bracelet and the 39 mm octagonal case still keeps its edges. The cream dial is aging well too. The Screw down crown, hardened mineral crystal, built in shock absorption, and water resistant to 600 metres (no, don’t test it) all add up to a proper, professional sports watch.

The caseback is in nice condition with the standard Zenith logo.

The crown is unsigned. To be honest we don’t know if this is original or a service replacement as we have seen other Plongeur 600m with unsigned crowns. You can tell the difference between a standard Defy where the crown was positioned at 3 o’clock and the upgraded 600m version where the crown has moved to 4. This was meant to add further protection to the crown and case from being damaged (c.f. Seiko’s turtle watches of the same era).

As well as  a special locking ring around the crystal to create a particularly effective seal and a shock-resistant rubber bush that suspends the whole movement inside that tough steel case, the Defy ran using a caliber 2552, 23 jewel automatic movement.

Gay Frères was the preeminent maker of watch bracelets in the 20th century and made many bracelets for Zenith in the 1970s (including the famous ladder bracelet used with the El Primero). Our example here is almost certainly the watch’s original bracelet and still looks good and shows some but not too much stretch. The clasp also holds firm and is dated from early 1971.

Defy is an english translation of the French Defi or Challenge. Used by Zenith when they wanted to move into the Sports/Dive watch space in 1968. One story goes that Zenith attached a watch to the propeller of a Belgian ferry. After 6 hours they removed it. The watch was still working!

It remains one of Zenith’s key model lines which is why they made a big splash at Baselworld earlier this year with a new Defy range. Nice watches but not like this original.

So, it’s rarer than the proverbial hen’s teeth. It is in very good condition, running smoothly, the dial depicts a life well lived, and it has a celebrated bracelet too. For those who know their vintage dive watches, this is a real find.


  • Name: Zenith Defy Plongeur 600m

    Model: Defy Plongeur 600m Professional

    Reference: A3646

    Year: 1971

    Case Material:  Stainless steel

    Case Width:  without crown: 39 mm

    Case length, Lug to Lug: 44 mm

    Case height: 15 mm

    Lug width: 18 mm

    Approx Weight:  110 grams

    Crystal:  hardened crystal is in fair condition

    Dial: Cream/aged dial and black/gold hour markings. The dial is signed Swiss Made T. Date at 4.30

    Hands:  Steel, lumed

    Crown:  Unsigned original? crown

    Movement:  Automatic 2552

    Functions: Hours, minutes, seconds, date

    Case Back: Steel, Zenith logo

    Strap:  Gay Freres original bracelet

    Strap length (long/short side): 65/45 mm

    Water Resistance: We do not guarantee any watch to be waterproof, unless stated

    Last known Service: Not Known

    Comes with a Chrono Duo Presentation box.