Tianjin Sea-Gull automatic (ST) mechanical movements

 

Tianjin Sea-Gull automatic (self-winding) mechanical movements are generally organized and released in the following chronological sequence of development by the Tianjin Watch Factory / Sea-Gull Group: [1]

• Sea-Gull ST16 (introduced c. 1980s / early development era):
  • Features a Miyota-inspired simplified layout with a Seiko-style auto-winding rotor mechanism.
  • Runs at 21,600 vph with a ~36–39 hour power reserve and forms the basis for numerous multi-calendar and 24-hour variants (such as the ST1612). [1, 2]
Sea-Gull ST17 (introduced as an evolution of the ST16):
• Refined and upgraded architecture over the ST16, offering cleaner spacing, small-seconds, jump-hour, big-date, and power-reserve variants.
• Runs at 21,600 vph with a ~39-hour power reserve. [1, 2, 3]
Sea-Gull ST18 (introduced as a high-end thin movement):
• Modeled after the slim, high-beat Swiss ETA 2892-A2 architecture.
• Features a high-beat rate of 28,800 vph, around 172 components, a Swiss Incabloc shock system, and a ~42-hour power reserve. [1, 2, 3, 4]
Sea-Gull ST21 / ST2130 (introduced as a high-beat workhorse):
• A direct, high-frequency clone of the Swiss ETA 2824-2 (often informally referenced in early circles as the ST24).
• Operates at 28,800 vph (8 beats per second) with 28 jewels and a ~39–42 hour power reserve. [1, 2, 3, 4]
Sea-Gull ST22 (introduced as a twin-movement/modular concept):
• Features a unique configuration utilizing a pair of smaller ST6 automatic movement plates side-by-side or stacked on a common mainplate with open-heart or big-date options. [1]
Sea-Gull ST25 (introduced as a heavy-duty/complication platform):
• A larger, robust automatic family often built to host complex additions like power-reserve indicators, dual time zones, open-heart setups, and floating/suspended tourbillons running at 21,600 vph with a ~45-hour power reserve. [1, 2, 3]

(Note: The famous manual-wind Sea-Gull ST19 chronograph originates separately from the time line above. The ST19 design is descended from the Swiss Venus 175 blueprints during Project 304 in the early 1960s, rather than belonging to the main self-winding ST-series automatic timeline above.) [1, 2, 3]

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