David Osei

Sports Watch Editor

David obsesses over dive, chronograph and pilot watches. Ex-Royal Marines diver, he field-tests every tool watch he reviews — Rolex Submariner to Seiko Turtle.

Articles by David Osei (3)

blancpain

Blancpain Fifty Fathoms No Radiolumin: The First Tritium Dive Watch

How French Navy radiation concerns pushed Blancpain to develop the first tritium dive watch in 1957—a safety innovation that changed military spec standards forever.

April 23, 2026

seiko

Seiko 6159-7001 'Professional Diver': The 300m Pioneer Nobody Knows

How Seiko achieved 300m water resistance in 1968—before Rolex's Sea-Dweller—using monocoque aviation engineering, yet this pioneering dive watch remains obscure.

April 23, 2026

iwc

IWC Mark Series Sweep Seconds: Why Military Spec Killed Hacking

Why did IWC's legendary Mark pilot watches deliberately omit hacking despite sweep seconds? The RAF's B.6/48 specification prioritized shock resistance over convenience—until civilian production changed everything.

April 19, 2026