The Patek Philippe Nautilus reference 3700/1A, launched in 1976 and known as the “Jumbo”, is Gérald Genta’s porthole-shaped steel sports watch. It has a 42 mm stainless steel case with a rounded-octagon bezel held by hinged “ears”, an integrated steel bracelet and a blue dial embossed with horizontal lines. It runs the ultra-thin automatic calibre 28-255 C, based on the Jaeger-LeCoultre 920, and is rated water resistant to 120 metres.

Genta is said to have sketched the shape in a few minutes, taking his cue from a ship’s porthole. Patek launched it with a steel case at a price above many gold watches, a bold step for a maker known for dress watches. The 3700 stayed in the catalogue until about 1990, when it was replaced by the 3710.

The Jumbo is considered one of the defining luxury sports watches, and the community treats it as a grail piece, with prices well into six figures for good examples. The original 3700/1A is no longer made, but the Nautilus remains in production in the current collection.