Yacht-Master models are equipped with calibre 2236 (Yacht-Master 37) or calibre 3235 (Yacht-Master 40 and Yacht-Master 42), self-winding mechanical movements entirely developed and manufactured by Rolex. They offer outstanding performance, particularly in terms of precision, power reserve, convenience and reliability. The power reserve of calibre 2236 extends to approximately 55hours, and for calibre 3235 to approximately 70 hours.