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Mid-tier supplier movement · caliber Fortis Caliber F-2000 (ETA 2824-2 base, automatic, 38-hour power reserve) · 38h power reserve
Medium-large: suits wrists 6.5 in+ (16.5 cm+)
42 mm case. Wears confidently on average to larger wrists. May overhang on slender builds.

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Authentication

The Marinemaster M-42 unidirectional bezel must rotate counterclockwise only; bidirectional rotation means the ratchet has failed.

Known issues in the market
  • The Cal. F-2000 is ETA 2824-2 based; verify through the caseback.
  • Bezel direction failure is a common fault on used dive watches.
AreaWhat to checkWhat is correctRed flag
caseUnidirectional bezel rotationBezel rotates counterclockwise only; ratchet engages at each positionBezel rotates both directions; ratchet has failed
movementCal. F-2000 ETA 2824-2 baseETA 2824-2 base visible through caseback; Fortis-signed rotorNon-ETA-2824-2 architecture; movement swap
crystalSapphire with anti-reflective coatingSapphire crystal; anti-reflective coating visible on inner surfaceNon-sapphire or cracked crystal; coating delamination
Common legitimate replacements
  • Bezel insert; Fortis OEM only for correct markings.
  • Crown; Fortis-signed screw-down.
Expert resources: Fortis authorized service; ETA 2824-2 service network.

Authentication guide

Last reviewed June 2026

The Marinemaster is Fortis's dive watch, certified for 200m. It runs the Fortis F-2000 caliber (ETA 2824-2 base). Fortis is the official watch of Russian Space Agency cosmonauts, though the Marinemaster is the dive line rather than the pilot line. Key authentication points are the bezel action and caseback caliber designation.

Known reproduction risks

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LOW

Not a significant reproduction target at this price.

  • Fortis rotor branding absent after service
  • Bidirectional bezel
  • Caseback without Fortis designation

Dial variants by era

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EraDescriptionIdentifiers
2021 to presentBlack or blue dial with mixed indices and Arabic accents. Date at 3. Unidirectional rotating bezel. 42mm steel case at 12.3mm height.
  • "FORTIS" at 12, "MARINEMASTER" and water resistance spec below
  • Unidirectional rotating bezel with 60-minute scale
  • Date at 3 with no cyclops
  • 42mm steel case
  • Sapphire caseback showing ETA 2824-2 base with Fortis decoration

Service part flags

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Movement (Fortis F-2000)

Original: ETA 2824-2 with Fortis finishing and branding on the rotor. Caseback reads Fortis F-2000 or the base caliber designation.

Replacement tells
  • Bare ETA 2824-2 rotor without Fortis branding after service
  • Caseback reading only the ETA caliber without Fortis designation

Case back markings

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2021 to present
  • Reference F-2040.11 or variant
  • "FORTIS" and brand identification
  • Fortis F-2000 / ETA 2824-2 designation
  • 200M water resistance
  • Serial number

Movement tells

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  • ETA 2824-2 power reserve is 38 to 42 hours. Standard service indicators apply.
  • Unidirectional bezel ratchet should click with no backplay.
Sources: Fortis Marinemaster official product documentation.

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