Officine Panerai marks each of the company’s Classic Yachts Challenge seasons with a special Regatta timepiece. Limited to 500 pieces, this year’s Radiomir Regatta One/Eight Second (about $17,000) is a split-second foudroyante chronograph that enables the simultaneous timing of two events. The watch, which can also calculate boat speed in knots, features a subdial positioned at 9 o’clock with a hand that spins at the dizzying speed of one rotation per second, allowing wearers to track times that are precise to an eighth of a second. At 3 o’clock, another subdial features a minute counter with the scale in knots (nautical miles per hour). Watertight to about 100 meters, the brushed-titanium 47 mm case houses an automatic OP XXI calibre movement that has a double-column wheel and an antishock device to protect the movement even in the roughest seas.