Sitting alongside link the time-and-date Broadsword and the Arrow monopusher chronograph I reviewed last summer, the Argonaut forms the most dive-ready of the HMAF (Her Majesty's Armed Forces) lineup and uses a similar Dirty Dozen-inspired case shape, with two oversized crowns. Sized at 42mm in hardened steel with a lug-to-lug distance of 49mm, the Argonaut's traditional two-piece case and slightly domed sapphire crystal come in at 15mm thick.