Seiko 6117B Movement: A Cult-Favorite GMT Caliber from the Golden Era

The Seiko 6117B is a mechanical automatic movement produced in the 1970s. It belongs to the iconic 6117 family, famous for powering Seiko's first generation of GMT watches—particularly the Navigator Timer and World Time models. Known for its robustness and reliability, the 6117B remains a beloved choice among collectors and vintage watch enthusiasts.

Evolution of the 6117 Series

The 6117 series began with the 6117A and was soon succeeded by the improved 6117B. Both movements offered a 24-hour GMT hand, making them ideal for travelers and professionals crossing time zones. The “B” variant added subtle but meaningful refinements, especially to the gear train and rotor design, which improved winding efficiency and stability.

Seiko developed the 6117 series in a period when it was racing against Swiss watchmakers, showcasing its growing expertise in crafting innovative, affordable alternatives to luxury Swiss brands. The 6117B, produced from the late 1960s to the early 1970s, became one of Seiko’s standout calibers of that era.

Technical Specifications

The Seiko 6117B is a 17-jewel automatic movement with the following specifications:

• Functions: Hours, minutes, seconds, date, and GMT/24-hour hand

• Frequency: 21,600 vibrations per hour (vph)

• Power Reserve: Approximately 42 hours

• Hacking Seconds: No (the second hand doesn’t stop when setting the time)

• Quickset Date: Yes (via the crown)

• Diameter: ~27.4 mm

• Height: ~5.8 mm

The GMT hand is independently settable in hourly increments. It rotates once every 24 hours, allowing the wearer to track a second time zone via a rotating bezel or fixed 24-hour chapter ring, depending on the watch model.

Watches That Use the 6117B

Some of the most well-known watches housing the Seiko 6117B include:

• Seiko Navigator Timer (ref. 6117-8000, 6117-6410)

• Seiko World Time (ref. 6117-6010, 6117-6400)

• Seiko 6117-8009 (U.S. market variant)

These watches are instantly recognizable for their 24-hour rotating bezels, bold indexes, and dual-time functionality. The Navigator Timer, in particular, became a staple for international travelers and even U.S. military personnel.

Legacy and Collectibility

Today, the Seiko 6117B is considered a gem among vintage Seiko movements. Many of the watches built with this caliber are still functional after decades, a testament to Seiko’s build quality. Enthusiasts appreciate the honest, tool-like design of the Navigator Timer and the colorful, international flair of the World Time models.

Because of the relative affordability and historical charm, 6117B-powered watches are increasingly sought after in the vintage market. They offer a genuine GMT complication without the high price tag of modern luxury counterparts.

Final Thoughts

The Seiko 6117B stands as a symbol of Seiko’s ambition during the golden age of mechanical watchmaking. It’s a reliable, no-nonsense GMT movement that continues to win hearts with its practical functionality and classic design. For collectors, it represents an era when Seiko was making bold moves on the global stage—and winning.