In 2006, Patek Philippe launched the Nautilus Ref. 5980/1 A, an elegant yet resolutely sporty chronograph timepiece in a stainless steel case. Inside its 44m diameter case, beats a self-winding, column-wheel-controlled caliber 28-520 C chronograph movement.

While its architecture is based on the movement of the Patek Philippe Ref. 5960, the 28-520 C features an instant-change date in an aperture at 3 o’clock and also stands out with a number of highly interesting chronograph functions.

The chronograph hand with the flyback feature doubles as a constantly running sweep seconds hand. This is possible because in the new mechanism, the three fine-toothed chronograph wheels normally used to start and stop time measurements have been replaced by a virtually friction-free, vertical disc-type clutch.

The monocounter that dominates the bottom half of the dial is unusual as well. It features three concentric scales. Whenever the stopwatch function is activated, this counter starts counting the elapsed minutes and hours.

This fascinating movement is accommodated in the subtly redesigned 44-mm Nautilus case, making it currently the largest model in the collection. The two chronograph push pieces are so well integrated in the caseband that it seems as if the 1976 design had been conceived for a chronograph to begin with.

The back of the three-part case incorporates a sapphire-crystal window, revealing the artistic decoration of the superb movement, the gold rotor, and the gold-filled, embossed Geneva Seal.

The Nautilus Ref. 5980/1 A has a stainless steel case with an integrated stainless steel bracelet. The outer bracelet links are satin-finished and the middle links are polished.

Technical details

Model: Patek Philippe Nautilus chronograph Ref. 5980/1A Steel

Movement
Caliber CH 28-520 C
Self-winding mechanical movement, column wheel-chronograph, sweep seconds (chronograph hand)
Diameter: 30 mm
Height: 6.63 mm
Number of parts: 327
Number of jewels: 35
Power reserve: Max. 55 hours
Winding rotor: Central rotor in 21K gold, unidirectional winding; oil-free ball bearing with zirconium balls
Balance: Four-arm Gyromax with four inertia blocks
Frequency: 28,800 semi-oscillations/hour (4 Hz)
Balance spring: Breguet

Functions
Two-position crown:
– Pulled out: Setting the time
– Pushed in: Winding

Displays
Center hour and minute hands
Sweep chrono/seconds hand
Dual subsidiary counter dial at 6 o’clock with
– 60-minute counter (counts elapsed minutes on two concentric scales from 0 to 30 and 30 to 60, respectively)
– 12-hour counter
Display apertures:
Quick-action date at 3 o’clock according to a 1991 Patek Philippe patent (date change in less than one-tenth of a second)

Function buttons
– Chronograph start and stop at 2 o’clock
– Chronograph hand reset and flyback at 4 o’clock

Corrector push piece
Rapid date correction at 8 o’clock (setting stylus in ebony and white gold)

Hallmark
Geneva Seal

Case
Three-part case (back, caseband, bezel)
Stainless steel, sapphire-crystal caseback, water-resistant screw-down crown
Bezel with vertical satin finish
Water-resistant to 120 meters
Case dimensions
3 to 9 o’clock: 44 mm (including hinges)
3 to 9 o’clock including crown: 45.60 mm
6 to 12 o’clock: 38.50 mm (bezel); 45.52 mm (including lug links)
2 to 8 o’clock: 40.50 mm
Height: 12.16 mm

Dial
Gradation from dark blue in the middle to black at the periphery, horizontal embossed pattern
9 applied baton hour markers in 18K white gold with luminous coating
Baton-style hour and minute hands in 18K white gold with luminous coating
Steel seconds/chronograph hand, sandblasted and rhodiumed
Monocounter in rhodiumed subsidiary dial
Baton-style hour-counter hand with counterweight, sandblasted and rhodiumed brass
Arrow-shaped minute-counter hand with counterweight, sandblasted and rhodiumed brass with red lacquered tip

Bracelet
Stainless steel, middle links polished, outer links satin-finished, stainless steel fold-over clasp

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