How long does a self-winding watch stay wound?
The Rolex Watch Company improved Harwood's design in 1930 and used it as the basis for the Rolex Oyster Perpetual, in which the centrally mounted semi-circular weight could rotate through a full 360° rather than the about 200° of the 'bumper' winder. Rolex's version also increased the amount of energy stored in the mainspring, allowing it to run autonomously for up to 35 hours.
How long does a Rolex Oyster Perpetual from 1930 self-winding watch stay wound?
35 hours
Automatic watch
When fully wound, Harwood's watch would run for 12 hours autonomously. It did not have a conventional stem winder, so the hands were moved manually by rotating a bezel around the face of the watch. The watches were first produced with the help of Swiss watch manufacturer Fortis and went on sale in 1928. 30,000 were made before the Harwood Self-Winding Watch Company collapsed in 1931 in the Great Depression. 'Bumper' watches were the first commercially successful automatic watches; they were made by several high grade watch manufacturers during the 1930s and 1940s.
How long does a Harwood "bumper" self-winding watch from 1923 stay wound?
12 hours
Automatic watch
No context provided
How long does a Miyota 8215 self-winding watch stay wound?
over 40 hours
No context provided
How long does a Chinese standard movement self-winding watch stay wound?
minimum 40-hour
Automatic watch
https://en.wikipedia.org/wiki/Automatic%20watch
Mechanical watch
https://en.wikipedia.org/wiki/Mechanical%20watch
Automatic quartz
https://en.wikipedia.org/wiki/Automatic%20quartz
Chinese standard movement
https://en.wikipedia.org/wiki/Chinese%20standard%20movement
When fully wound, Harwood's watch would run for 12 hours autonomously.
Automatic watch Harwood "Bumper" wristwatches: 1923
The length a self-winding watch can stay wound depends on the type of watch. When fully wound, Harwood's watch would run for 12 hours autonomously. Rolex Oyster Perpetual from 1930 self-winding watch can stay wound for up to 35 hours. A Chinese standard movement self-winding watch can stay wound for a minimum 40-hour. Miyota 8215 self-winding watch can stay wound for over 40 hours.  