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Movement tier: unclassified · caliber IWC Cal. 89361: in-house automatic flyback chronograph, 28,800bph, 68h PR, 38j; column-wheel, large date; Portugieser Yacht Club Chrono caliber · 68h power reserve (2.8 days)
Large case: suits wrists 7 in+ (18 cm+)
43.5 mm case. A bold, statement-size wear. Best suited to larger wrists where the case sits flush.

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Authentication

Test the regatta countdown timer; it must set correctly for both 5-minute and 10-minute pre-start sequences before purchase.

Known issues in the market
  • The regatta countdown adds complexity beyond a standard chronograph; service is specific to Cal. 89361 and requires IWC or IWC-certified expertise.
  • The pusher at 10 o clock activates the countdown; verify it operates cleanly and does not bind.
AreaWhat to checkWhat is correctRed flag
caseRegatta timer pusher at 10 o clockPusher at 10 o clock activates the regatta countdown; operates cleanly with no bindingPusher at 10 o clock binding or failing to activate countdown; may indicate service need
dialRegatta timer countdown displayCountdown function sets for 5-minute and 10-minute sequences correctly; countdown display advances cleanlyCountdown not advancing correctly; timer not resetting to the correct interval
casebackCal. 89361 movementCal. 89361 confirmed through caseback; regatta complication architecture visibleAny caliber other than 89361; standard chronograph without regatta mechanism
Common legitimate replacements
  • Original IWC Portugieser strap or bracelet; factory replacements are standard.
Expert resources: IWC Portugieser Yacht Club Chronograph IW390503 product documentation. IWC Cal. 89361 technical sheet.

Authentication guide

Last reviewed June 2026

The IW390503 Portugieser Yacht Club Chronograph uses a flyback movement (Cal. 89361) in a 45.4mm steel case with a rubber strap and push-button deployant. The larger diameter and rubber strap give it a more sports-oriented character than the standard Portugieser Chronograph.

Known reproduction risks

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HIGH RISK

Replica Portugieser Yacht Club Chronographs are common given the desirability of the Portugieser family.

  • Flyback function is the fastest test; a non-flyback chronograph movement is immediately apparent
  • Exhibition caseback on replicas shows a visually different movement architecture
  • Case diameter on replicas often deviates from the correct 45.4mm specification
  • Rubber strap construction on replicas is typically thinner and less structured than the original

Dial variants by era

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EraDescriptionIdentifiers
2009 to presentAnthracite or dark grey dial with three-register flyback chronograph. Applied Arabic numerals at 12, 3, 6, 9. Date subdial at 3.
  • Large 45.4mm case; the Yacht Club Chronograph is one of the larger Portugieser variants
  • Flyback chronograph with three registers
  • Rubber strap rather than leather as standard
  • "PORTUGIESER YACHT CLUB CHRONOGRAPH" text on the dial
  • Date in the subdial at 3 (not a simple window)

Service part flags

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Movement

Original: Cal. 89361 flyback chronograph, same caliber as used in the Portofino Chronograph IW391036. The movement is visible through the exhibition caseback.

Replacement tells
  • Standard (non-flyback) chronograph function; the Yacht Club Chrono should reset and restart in a single lower-pusher press
  • ETA 7750-based movement in the exhibition caseback

Case back markings

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2009 to present
  • Exhibition caseback showing Cal. 89361
  • Engraved ring: IWC SCHAFFHAUSEN with reference IW390503 and serial
  • No soft iron cage (Portugieser family is not an anti-magnetic Pilot reference)

Movement tells

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  • Same Cal. 89361 movement tells apply as for the Portofino Chronograph IW391036.
  • The larger case and exhibition caseback make movement verification straightforward; request a caseback photo in any remote purchase.
Sources: IWC Portugieser product page; WatchUSeek -- Portugieser Yacht Club thread.

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