Timekeepers Club / September 2, 2022

Grönefeld 1969 DeltaWorks

Bart and Tim Grönefeld, aka ‘The Horological Brothers’, are third generation watchmakers. Like their forebears, they live and work in Oldenzaal in the Netherlands. They are proud of their heritage as well as the nation they call home.

The Netherlands is characterised by flat, low-lying plains. Indeed, 17% of the land was formerly underwater. Unfortunately, the country’s unique topography has sometimes led to floods and, sadly, loss of life. In 1953, a north-westerly storm of biblical proportions, coupled with the spring tide, led to huge swathes of the Netherlands flooding. Unfortunately, 1836 people lost their lives, numerous animals drowned and vast numbers of people were displaced.

A consequence of the country’s unique topography and its sometimes perilous relationship with the sea is that the Netherlands has become a world leader in the field of water management and associated engineering. The ‘Delta Works’, built to protect the Zeeland region, comprises dams, dikes, locks, sluices and a storm surge barrier. Taking several years to construct, the Delta Works includes the world’s largest surge barrier and is widely regarded as a triumph of engineering.

Inspired by the Dutch Delta Works, The Horological Brothers have conceived their first sports utility watch, the aptly named 1969 DeltaWorks which also references the year Bart was born. The model is designed to cope with the perils of water ingress and shocks while still upholding the elevated standards of horology and traditional craftsmanship that are synonymous with the Grönefeld name.

The dial – its purpose is clear

The dial of the 1969 DeltaWorks presents the essentials of time, namely, hours, minutes and seconds. There is nothing superfluous. In fact, when designing the watch, Bart and Tim were keen to ensure that the dial imparted information in a clear, intelligible format. To deliver peerless legibility, day or night, the hands and hour markers are treated with Super-LumiNova®, that produces a blue glow in restricted light.

While the dial is highly practical it is still enriched with numerous details. For example, the hour track sits on a higher plane than the central dial area and small seconds display. The plump lancine-style hour and minute hands deliver impressive readability even in the most challenging conditions. At the fulcrum of the hands, the ‘centres’ are black polished to a gleaming conclusion.

The small seconds display features ‘60’, presented in an orange hue, a respectful nod to the brothers’ homeland. Likewise, the country of origin is proudly proclaimed at the base of the dial.

A watch for all occasions

The 1969 DeltaWorks is presented in a 45mm stainless steel case, measuring 12.5mm in height. The case features an integrated strap that ergonomically encircles the wrist, conferring a high degree of wearer comfort while appearing smaller than its stated dimensions would suggest. The scale of the case endows the watch with a generously proportioned dial area, augmenting legibility but without appearing unduly large. Every aspect of the case has been carefully considered.

Two inserts are integrated within each caseband, steadfastly secured to the main body of the case. The inserts are offered in two formats: stainless steel, matching the case material, or titanium shrouded in coloured FKM rubber, designed to match the shade of the strap. A notable attribute of the latter option is that there is less risk of the case band picking up annoying scratches. Throughout the composition, the case juxtaposes brushed and highly polished surfaces, contributing to the model’s notable allure.

A triple-seal, screw-down crown mitigates the risk of dust or water ingress. In addition, the crown features an ingenious safeguarding system. When the Grönefeld logo on the crown is perpendicular to the dial and pointing upwards, the triple-seal, screw-down crown delivers maximum protection. The sapphire crystals, to the front and rear, are thicker than normal and, by default, stronger. As a result of the aforementioned details, the watch is water resistant to 100m, making it suitable for an array of leisure pursuits, including swimming, sailing and windsurfing.

The 1969 DeltaWorks is offered in an array of different coloured rubber straps. Grönefeld has selected FKM rubber in preference to conventional rubber as it proves more supple, more resistant and it retains its colour for longer. The exterior of the strap features a wave pattern, while the inside of the strap is decorated with a motif formed of numerous Grönefeld logos, allowing the wearer’s wrist to breathe. The strap can be cut to length for optimal sizing, while the micro adjustable clasp, featuring gleaming facets and relief engraving, allows the wearer to fine tune the union between the strap and the wrist.

The aforementioned pane of sapphire crystal, positioned to the rear of the watch, affords views of the beautifully appointed, self-winding movement. The case back features ‘GRÖNEFELD’ and ‘DELTAWORKS’ in relief, while the name ‘Oldenzaal’ is discretely engraved opposite the crown, an elegant reminder of where the Grönefeld family’s watchmaking story began.

The movement – no compromises

When conceiving the 1969 DeltaWorks, Bart & Tim were keen to ensure the watch was suitable for daily wear and compatible with an active lifestyle. With this in mind, they decided it must feature a self-winding movement encompassing the same exalted finishing as other Grönefeld timepieces. Put simply, the brother’s wouldn’t countenance any compromises. As such, the resultant movement, the calibre G-06, is worthy of the term ‘Haute Horlogerie’.

Brand devotees may recognise the calibre G-06, an automatic movement first used within the company’s 1941 Principia Automatic. However, while many elements have been carried over to the 1969 DeltaWorks, there are some additional details which enhance robustness, imbuing this version with its own distinctive character.

For instance, a notable feature specific to this model is the distinctive oscillating weight. The openworked architecture features four stainless steel arms, presented in a double-spoke design. These arms are connected to an 18K gold mass adorned with a wave motif. Each of the four arms is positioned beneath the gold mass and projects beyond, sitting above a circular ledge. Should the watch be subject to a sudden shock, the elongated arms will prevent the oscillating mass touching the inside of the sapphire crystal or striking the bridges below

The movement is intended for the most discerning watch collectors. The rotor is completely hand finished and turns on ceramic ball bearings, preventing wear and eliminating the need for lubrication. Meanwhile, the stainless-steel bridges replicate the façades of traditional Dutch houses, termed ‘bell gables’. Each bridge features a micro-blasted central section, framed with a hand-bevelled gleaming edge. Some of the bridges also feature relief engraving. Each movement is fitted with a plate engraved with ‘ΔW’ (signifying DeltaWorks) along with its unique movement number.

The Grönefeld 5-arm, double spoke gear train wheels exhibit a contemporary character, but their circular grained surfaces pay due reverence to fine watchmaking tradition. Their design, as well as the bevelled escape wheel teeth, prevent the oil from dissipating, thereby mitigating wear. The free-sprung balance mitigates positional influence and delivers superior rate stability. The escapement is adjusted to heat-cold, isochronism and six positions.

Gold chatons stand testament to the no-compromise specification of this movement. In addition, the mirror polished screws feature chamfered rims and slots. Numerous surfaces gleam, courtesy of the mirror-polishing which has been patiently executed by time-served hands. The inventory of different decorations includes snailed, grained, spotted and frosted surfaces, indulging the desires of purists.

Once again, there are no compromises. Everything is reassuringly Grönefeld.

A remarkable choice When conceiving this watch, Bart & Tim wanted to produce a model that indulged purists with a remarkable choice of colours and styles. The 1969 DeltaWorks is available with 3 different dial designs/colours, 5 different strap options and, finally, a choice of stainless steel inserts or colour-coordinated FKM rubber-clad inserts.

The 1969 DeltaWorks is the distillation of three generations of watchmaking know-how, the professional journeys of both Horological Brothers and the manifestation of their extraordinary passion for horology.

Technical specifications

Grönefeld 1969 DeltaWorks

The 1969 DeltaWorks is available with 3 different dial designs/colours, 5 different strap options and, finally, a choice of stainless steel inserts or colour-coordinated FKM rubber-clad inserts

Limited production


  • Material: Stainless steel AISI 316L (1.4435)
  • Diameter: 44.5 mm
  • Diameter bezel: 43.4mm
  • Thickness: 12.5 mm
  • Lug to lug: 53.0 mm
  • The 4 case inserts are available in colour matching FKM rubber clad or polished and brushed stainless steel
  • Screw down crown. Triple gaskets with upright logo
  • Water-resistant to 100 meters - 10 atmospheres – 330 feet

Dial and hands

  • Dial: Black, khaki or salmon
  • Flame-blued or polished steel extended Lancette hands with blue light emitting Super-LumiNova® Grade X1
  • Small poised seconds hand


  • Automatic in-house movement
  • Uni-directional winding mechanism
  • For 24 hours of autonomy 633 rotations of the Oscillating mass are required
  • Oscillating mass: Entirely decorated by hand. 18 karat solid gold segment. Stainless steel centre pivoted on a high precision ceramic ball bearing to avoid excessive wear. To prevent damage to the movement and winding mass the extremities of the 4 arms are extended and guided by the case and case-back
  • Diameter: 32.0 mm
  • Thickness: 5.5 mm
  • Number of parts: 231
  • Number of jewels: 31 jewels, partially set in solid gold chatons
  • Variable-inertia balance wheel with four white gold timing screws (diameter 10 mm)
  • Frequency: 21'600 vph (3 Hz)
  • Balance spring: Free sprung with triangle hairspring stud
  • Main plate: Spotted and ruthenium electroplated brass main plate
  • Bridges: Stainless steel, bevels polished by hand, micro-blasted centres, circular grain on the top to highlight the bridges shapes and relief engravings
  • Power reserve of 56 hours


  • Central hours and minutes
  • Small seconds at 6 o’clock

Strap and buckle

  • Integrated FKM rubber strap available in black, olive, blue, white or orange
  • Stainless steel 316L micro adjustable (7 increments over 9mm) folding clasp
  • Embossed Grönefeld and logo engraving
  • Opening must be done by operating both push buttons at once

MSRP: EUR 49'300 (excl. taxes)

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