023 IWC Mark 1 B Uhr with recent factory service and archive documents


With official IWC archive documentation

Categories: ,


This is one of the rarest & most collectable of the famed WW II German “B-Uhrs”, the IWC version. The watch has just returned from Schaffhausen where it underwent a full service & was fitted with a brand new strap made by IWC in the original pattern and it is accompanied by official IWC factory archive papers and invoices.

These watches are commonly known as “B-Uhrs” short for “Beobachtungsuhr” or observer’s watch; however a more correct translation would be “Navigator’s watch” and were used by the navigator to perform navigational calculations.

These IWC watches have the highest quality movement ever fitted in a B-Uhr wristwatch, it is a calibre 52T marine chronometer quality, with a cut Guillaume balance equipped with heavy gold adjusting screws. It has 16 jewels, most of them in chatons and the seconds hand is direct driven. The balance spring has a Breguet terminal curve and the balance cock is fitted with a “swan’s neck” micrometer regulator. It has a hacking system operated by the winding crown, when pulled to the hand setting position a small spring pushes up against the 4th wheel & stops the balance. Only 1,000 of these watches were made & were shipped to IWC’s Berlin agent, Siegfried Heindorf, in 1940. Knowing that the heaviest Luftwaffe bomber losses were during the second half of 1940 (the Battle of Britain), it seems reasonable to assume that not many survived.

The case is unlike all other B-Uhr watches, it made from stainless steel with a separate antimagnetic movement cover. It has the specification number FL23883 engraved on the case side opposite the winding crown. And inside the case back the full history is also engraved, this shows the maker, IWC; the specification number FL23883 and the movement number 1014589. There is a separate anti-magnetic dust cover and this bears the case number 1033909, which is also stamped inside the case back.

The dial is unique style to IWC with a large triangle and 2 dots at 12 and the remainder of the hours as large luminous Arabic numerals, however unlike all the other makers, the 6 and 9 are open. The blued steel hands, including the sweep seconds, have heavy luminous radium paint.

These watches were not “issued” in the same way as in the Allied air forces, rather a bomber Navigator would be supplied with one prior to a raid and it would be returned to the stores after the mission was de-briefed.

Dial & movement are both 99+% whilst the case is 95%.
Diameter 55mm; Lug to Lug 66mm; Height 17mm., it takes an 25.5mm strap and a modern replica strap is fitted.

£27,500.00 (approx. $31,500.00 US)