Rare 1983 RAF issue CWC G10 '6BB' offset hatch 'Medium Fatboy'
Rare watch in excellent condition
£625.00
Out of stock
The early CWC G10s, from 1980-82 were the real 'Fatboy' G10s, with the deep case to accommodate the ESA/ETA 536.121 movement. From 1987 onwards, CWC G10s were produced with a thin case and low profile case back. In-between, from 1983-85 were a sequence of variants collectively knows as the 'Medium Fatboy' G10s.
Although the mid-case of the 83 variant is almost the same as the later thin case watches (just slightly thicker), the case back is much deeper and includes an anti-magnetic plate inside the case back. This gives the watch a bit of extra heft compared to the later watches.
The '83 version also has the characteristic 'offset' battery hatch. The hatch is the same size as the earlier Fatboy watches, but offset to the right, due to the position of the battery compartment in the movement.
The dial also retains the earlier 'Swiss' marking at the 6 position, which was replaced with 'Swiss Made' after 1987.
The movement for the '83 watches is the ISA 947.111. This quartz movement has a plastic base plate with integrated circuit and was only used for one year of production before being superseded by the ETA 555/955 series movements. The movement can be repaired and serviced so it is a practical and maintainable watch to own in the long run. The case back is also far easier to open than the 1980-82 Fatboys, again enhancing its maintainability. It also has a 'trimmer' allowing the movement to be regulated for accuracy.
One other feature of the 1983 G10s is that the movement has a date disc although there is no window in the dial so this is hidden.
The majority of 1983 G10s were issued under an Army contract and marked with the W10 service code, but a small number - 965 altogether - were issued under an RAF contract with the 6BB service code marked on the caseback.
This example is in excellent original condition, as described in the condition report, and has just been fully serviced.
The watch is supplied on a new grey cotton NATO strap.
The case and back are very clean and with only minor marks. The case back is virtually unmarked with barely a hint of strap burn suggesting the watch was only very lightly used. The case back has the correct markings including the 6BB RAF service code, NATO stock number, serial number and issue year. The crystal is a flat profile replacement with matte tension ring fitted. The dial and hands are in absolutely lovely condition with great lume colour. Please refer to the images to make your own judgement about the cosmetic condition of the watch. The images form an important part of the description.
The watch was subject to a full stripdown, clean and service in September 2025. The case parts were stripped and ultrasonically cleaned and the original ISA 947.111 movement was serviced.
The movement was fully stripped, mechanically and ultrasonically cleaned using waterless solutions and hot air dried. The movement was rebuilt and lubricated using Moebius oils. Images of the movement rebuild are included in the listing. The watch hacks and sets from the crown correctly. All the seals were also replaced and greased, including the back gasket, the battery hatch and crown gaskets.
One noteworthy feature of the 947.111 movement is the fact that it has a date disc, even though there is no date aperture in the dial. This was simply a case of the available movement being produced in volume and available at the time had a date disc. Often the calendar works are subsequently removed when the watches are serviced/repaired, but where they are present we make sure that are properly serviced along with the rest of the watch and are in full working order - even if you can't see it! It even turns over at midnight.
The watch was regulated on a quartztester machine and is running on the bench at + 0.02 seconds per day, equivalent to + 0.6 seconds per month, which is well within the +/-10 seconds per month specification. Accuracy may differ from this when in use. Note the thick case back with antimagnetic plate prevents the quartztester from reading the pulse with the case back fitted - in the image the case back is not fitted and the battery, which is normally held in place by the case back, is being held in place with an elastic band.
The watch is absolutely suitable for everyday use, but it is vintage watch so is not recommended for sports or use in extreme conditions. The watch has not been pressure tested so water resistance is not guaranteed. This watch is covered by our non-waterproof 6 month guarantee.
Issued: Yes
Issue details: UK MoD, RAF
Date of manufacture: 1983
Production numbers: 965
Movement: ISA 947.111
Diameter: 36mm
Lug width: 18mm
Hacking: Yes
Case back: Snap
Screwdown crown: No
Bracelet: cotton NATO
UK MoD issue
1983 'Medium Fatboy'
Original ISA 974.111 quartz movement
Recently serviced and regulated
Excellent condition
Supplied on new cotton NATO-type strap
6 months non-waterproof guarantee
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