The Seiko Prospex SPB379 is larger, has a longer stated power reserve and carries a higher nominal water-resistance rating. The Christopher Ward C65 Dune GMT is more compact on paper. Both are described as caller-style GMTs, so frequent travelers should compare their time-setting workflow rather than assume either has a jumping local-hour hand. The better choice depends on fit, design, how you use the GMT display, and current price and availability in your market.
How the specifications compare
The figures below are manufacturer-published specifications, not independent test results. Seiko’s page covers the SPB379J1; Christopher Ward’s manual covers the C65 Dune GMT.
| Specification | Seiko Prospex SPB379J1 | Christopher Ward C65 Dune GMT |
|---|---|---|
| Movement | Seiko Caliber 6R54; automatic with manual winding | Sellita SW330-2; self-winding mechanical |
| Power reserve | Approximately 72 hours (three days) | Up to 56 hours |
| Stated accuracy/tolerance | +25 to -15 seconds per day | -20/+20 seconds per day |
| Case diameter | 39.5 mm | 38 mm |
| Thickness/height | 13.6 mm | 11.9 mm |
| Lug-to-lug | 46.4 mm | 43.7 mm |
| Water resistance | 20 bar | 15 ATM (150 metres) |
| Crystal | Curved sapphire with inner anti-reflective coating | Glass-box sapphire |
| Strap width | 20 mm | 20 mm |
| Other details | Rotating compass inner ring, screw-down crown, see-through screw case back, leather band | Date, screw-down crown, display caseback, Super-LumiNova Grade X1 hands and indexes |
Sources: Seiko’s SPB379J1 product page and the C65 Dune GMT official manual. Seiko’s displayed regional price is in Swedish kronor; it is not directly comparable with a price in another market or currency.
What the GMT function means for travel
Fratello’s September 10, 2023 comparison characterizes both watches as “caller” or “office” GMTs. In general, a caller GMT lets you track another time zone with a 24-hour hand, but changing your local time while traveling is less convenient than on a flyer, or traveller, GMT, where the local hour hand jumps independently in one-hour steps.
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- ELEGANT DESIGN: Round stainless steel case with blue rotating bezel, white dial and steel bracelet for a professional and refined look
- GMT function: Automatic movement with GMT function for monitoring two time zones, ideal for international travelers
- TECHNICAL SPECIFICATIONS: Diver watch with water resistance up to 300 m, sapphire crystal and date indicator
- SPECIAL EDITION: Prospex Collection 60th Anniversary commemorative model, representing Seiko excellence in the sports watch industry
- BRACELET: Solid stainless steel bracelet with safety clasp, perfect for everyday wear and sports activities
Christopher Ward’s manual describes setting local time by moving the hour and minute hands and moving the GMT hand in one-hour increments. Seiko describes the SPB379’s 24-hour hand as a dual-time display function. Neither description supports treating these models as watches with an independently jumping local-hour hand. If you regularly cross time zones and want to adjust local time quickly without disturbing the minutes, study the setting procedure and compare it with a flyer GMT before buying.
The C65 manual puts the purpose simply: “As a GMT timepiece, this Dune lets you monitor two time zones at once.”
Fit: the C65 is more compact on paper
The C65 measures 1.5 mm less across, 2.7 mm shorter lug-to-lug and 1.7 mm thinner than the SPB379. Those dimensions make the Dune GMT the more compact option by specification, while the Seiko has a larger, thicker presence. They are useful starting points, not guarantees of how either watch will wear: wrist shape, strap or bracelet, and personal preference all matter. Try the exact configuration on if possible.
Reserve and stated accuracy
Seiko lists approximately 72 hours of power reserve for the SPB379’s 6R54; Christopher Ward specifies up to 56 hours for the C65’s SW330-2. The Seiko’s stated reserve is longer, which may be useful if you rotate watches and want more time before winding and resetting one that has stopped.
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- RELIABLE GMT MOVEMENT: Automatic GMT movement delivers accurate timekeeping and easy dual-time tracking for travel.
- PROFESSIONAL DIVE WATCH: 300M water resistance makes it suitable for diving, swimming, and everyday adventures.
- DURABLE STAINLESS STEEL: Premium stainless steel case and bracelet offer lasting durability and a comfortable fit.
- SCRATCH-RESISTANT CRYSTAL: Sapphire crystal provides excellent clarity while helping protect the dial from scratches.
- CLASSIC & VERSATILE DESIGN: Black dial with a timeless Prospex heritage design, ideal for business, casual, and outdoor wear.
The published daily tolerance ranges are +25 to -15 seconds for Seiko and -20/+20 seconds for Christopher Ward. These are stated specifications, not a prediction of the measured performance of an individual watch. The ranges are close enough that they are unlikely to settle the choice on their own.
Water resistance and intended use
The SPB379 is rated to 20 bar; the C65 is rated to 15 ATM (150 metres). The numbers give the Seiko the higher nominal rating, but a rating alone does not establish suitability for every water activity. Christopher Ward’s manual cautions that water-resistance figures are guidelines and that movement and impacts can affect pressure exposure. Consider the manufacturer’s guidance for your specific use rather than reading either rating as an unconditional activity guarantee.
Rank #4
- WATER-RESISTANT: these water-resistant men's dive watches are ISO scuba-approved to depths of 200 meters
- SOLAR: this rugged diver's watch features Seiko's first ever solar GMT movement, powered by any light source for a 9-month power reserve
- STAINLESS STEEL: features a durable stainless steel watch case, bracelet, and rotating elapsed timing bezel
- LUMIBRITE DISPLAY: this men's automatic watch features a highly-legible display with LumiBrite hands and markers
- 5K65 CALIBER: equipped with the reliable caliber 5K65 automatic movement, this accurate men's watch keeps precise time
Design and configuration
Seiko Prospex SPB379
The SPB379 brings Alpinist design cues, including a rotating compass inner ring. Seiko’s regional product page lists it with a leather band. That combination gives it a more instrument-like, outdoors-oriented look than the Dune GMT.
Christopher Ward C65 Dune GMT
The C65 pairs a retro-styled case with a date and glass-box sapphire. Its manual documents quick-release pins for straps and bracelets, as well as bracelet micro-adjustment. Check the exact market variant and what comes in the box; configuration can differ.
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- SEIKO WATCH – Seiko SFK001 wristwatch with a GMT hand function.
- DIAL DESIGN – Blue dial provides the watch face design.
- CRYSTAL – Sapphire crystal construction.
- BEZEL – Unidirectional rotating bezel design.
- WATCH DIAMETER – 45 mm.
Both watches list a 20 mm strap width, which gives buyers a common nominal width for replacement options. Width by itself does not establish compatibility with a particular bracelet, end link or strap, so verify the fit for the exact watch and accessory.
Price, availability and the published head-to-head opinions
There is no established current, apples-to-apples price comparison here. Seiko’s displayed price is regional, and the Fratello comparison dates to September 10, 2023; its price comments are historical rather than a current buying quote. Check the exact reference, seller, currency, taxes, included bracelet or strap, and local availability before comparing offers.
In that 2023 Fratello article, Jorg Weppelink favors the C65 Dune GMT and praises its finishing and bracelet, while Daan de Groot prefers the SPB379’s Alpinist look and compass bezel. Those are the authors’ personal preferences, not objective test findings.
Which one should you choose?
- Choose the SPB379 if you want the Alpinist styling and compass inner ring, prefer the larger case, or value its longer published reserve and higher nominal water-resistance rating.
- Choose the C65 Dune GMT if you prefer the more compact listed dimensions, retro case styling, or the documented strap and bracelet adjustment features.
- Look beyond both if your priority is a flyer GMT with an independently jumping local-hour hand for frequent travel. The available descriptions characterize these two as caller-style GMTs.
Before deciding, compare the exact configuration and local price, and try the watches on if fit is close. Their differences are more meaningful than a blanket claim that one is universally better.
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