Build and Servicing

The Clock Gallery

OFFSHORE Professional chronographs combine traditional watch making skills with the latest laser cutting and CNC machining to produce completely unique timepieces. Every component has been designed and engineered from scratch or selected and modified based solely on the principle that only the best is good enough.

The workshop is located at The Clock Gallery, 147 Pitshanger Lane, Ealing, West London. W5 1RH. Tel 0754 251 3984.

Darius (above) runs The Clock Gallery and as the name implies, he spends a lot of time servicing and repairing old clocks. He's also a master watchmaker who learned his profession on the Valjoux 7750 family of movements. The 7750 is one of the worlds finest movements, combining longevity with robustness and accuracy. Key to its strength is the integrated chronograph architecture.

The OFFSHORE Professional caliber

All OFFSHORE Professionals are built by Darius in his immaculate Ealing workshop. He also makes the modifications to the 7750 that turn it into the 775M2, adjusts timing to within chronometer standard, and then assembles each watch absolutely perfectly.

Rotor detail

A basic service and lubrication for your Field Engineer can be done by any competent watchmaker, just check they have experience with the Valjoux 7750 family. For servicing, plus any additional work such as upgrades and repairs outside the warranty period, then call Darius. All Field Engineer chronographs can be upgraded to the latest specification including new hands, dials, and the addition of day as well as date windows. The Clock Gallery holds a large inventory of OFFSHORE Professional spares to ensure fast and efficient repairs and servicing for many years to come.


The Valjoux 7750 chronograph movement on which the Field Engineer's 775M2 is based will run for 5 to 8 years between servicing, which is primarily refilling the reservoirs in the jewels with lubricating oil. If you look closely at the jewels (the light purple coloured rubies in the photographs) you'll see a small dot at their centre. The rubies are manufactured from crystals of Aluminium Oxide with a trace of Chromium and have a central hollowed out area to hold the lubricating oil. Like the sapphire front and back glass they have a mohrs hardness of 9 and so should quite happily last for several hundred years before showing any signs of wear.

OFFSHORE Professional Caliber Failure to service your chronograph will not damage it, but may cause it to run a little slower as the lubricating oil dries out and internal friction increases. All the main bearings are jewelled so their friction surfaces are extremely hard wearing and will take many years of completely unlubricated wear.

Over the years you may find the time keeping of any mechanical watch wanders slightly outside its original limits, generally caused by changes in lubricating oil viscosity. On the 7750 there is a small adjuster that will increase or decrease the balance spring length to compensate for this. It's visible in the photograph as a graded scale with a + and - symbol. Adjustment should only be done by a professional watch repairer as it is altogether too close to the balance spring (the helical spring behind it) to take the chance and try it yourself.

The self winding rotor runs on 5 ball bearings just visible at the very center of the movement. When it rotates in a clockwise direction it winds up the main spring. It takes 700 complete clockwise revolutions to wind the main spring, typically accomplished with 4 hours of normal wear. Once wound a simple mechanism prevents the main spring from being overtightened. The self winding rotor spins freely in the anticlockwise direction, and a rapid flick of the watch can create the famous 'Valjoux wobble' where the rotor spins so fast it makes the whole watch imperceptibly wobble. The Valjoux wobble is a great reminder of the beating machine running on your wrist. The rotor bearing will last for several hundred years before the ball bearings come loose, so you can quite happily flick your wrist to feel the wobble whenever you fancy. 

Parts count in the movement is a little over 110 or around 300, depending on how you count them (5 ball bearings, 3 rings, a rotor bolt, 2 rotor parts and a screw = one self winding rotor). It's close to 400 if you include the dial components, hands and movement holder.


MagnetismAlthough the movement has non magnetic components throughout its drive and time chains and a Faraday compliant outer case design, as with all mechanical instrumentation, it's possible for the timing to be affected by strong magnetic fields. 

You can check for magnetism in any watch by holding a compass up tight to it. If the compass needle moves a little (a quarter or half way around its dial) then your watch has picked up some magnetism. The Field Engineer pictured has been deliberately magnetized to test movement accuracy is not affected. Demagnetizing is a very simple process using a machine that most watch repairers will have to hand. A demagnetizing machine applies a very strong magnetic field to the watch, but then rotates the field in a chaotic way so it has no preferred alignment.


The inner case, also called the movement holder, is made from soft copper and plated in rhodium. It is visible in the movement photograph as the three matt silver outer rings. Minor shocks generally never reach the movement due to its mechanical isolation or are absorbed through elastic movement of the incabloc mechanisms fitted to all main bearings. Really big shocks are absorbed by the movement holder. Above a certain limit it is simply not possible to absorb impact energy elastically, so a plastic movement is required. This is plastic in the engineering sense and not something made from plastic (nothing in the movement is made from plastic as it becomes brittle with age). A particularly big impact will also cause the sub-dial hands to detach as they sit on relatively slim spindles which require full movement strip down to replace if they bend. The sub dial hands can be reattached, movement holder replaced if necessary, and your chronograph should start running again perfectly.

OFFSHORE Professional LumeThe Field Engineer outer case is made from solid 316L stainless steel with sapphire front and back 'glass'. Over time the stainless steel will pick up small scratches which can either be left or polished out. You should try and keep the push buttons and base of the crown free from substances that could work their way into the seals, generally anything too guey or fine powders. This is partly to prevent these substances from slowly working towards the seals where they might create a leak path, but primarily because a dirty watch is a horrible thing to behold.

Parts count in the case is around 32 including the movement holder locking.


The bracelet links, body and butterfly clasp are made from solid 316L stainless steel, with the double headed screw pins from 316H. L is low carbon (<0.003%), H is high carbon, with increased strength but lower toughness. H is ideal for small components and in particular for screw threads, L is ideal for the case and bracelet. The bracelet needs no maintenance other than the odd clean with a soft toothbrush to get any dirt out. Adjusting the bracelet is by removing links as shown below:

Bracelet Components

The screw pins that hold the links in place are double ended, with the small screw going into the larger one. This can make adjustment quite fiddly but it ensures the connection is much less likely to come loose. Because of this fiddleiness it is recommended that adjustment is done at a local jewellers. Parts count of a bracelet is bloody hundreds of fiddly little bits, many of which are lying in dark corners of my study. (about 250)


OFFSHORE Professional Strap CareNote that I'm working on a new standard fit strap in Teju skin.  Custom straps are also available. See the straps page for details on both.

The outer surface of the strap is made from leather and, just like shoe leather, it benefits from a polish every once in a while. The best polish to use is simple black shoe polish.

Eventually, and just like a good pair of shoes, the strap will become tatty and wear out. The Field Engineer end fitting will accommodate any of the Hirsch 22 mm curved end straps.

This interchangeability allows you to use different colour Hirsch straps if you feel like a change. Elsewhere on this website you'll see pictures of Field Engineers with blue and brown Hirsch straps. Parts count on a strap is 10.


Like the case, the buckle is made from solid 316L stainless steel and requires no maintenance. Adjusting the buckle is done by flipping the trident overpiece up with your thumb, moving to the required strap hole, and then snapping back together. The unsnapping and resnapping of the overpiece is deliberately firm as this is an operation you'll only ever do once or twice. Parts count is 32.

A mechanical chronograph is an expensive investment, and one it can be very difficult to justify when compared to the much cheaper battery powered quartz, digital or smart phone alternatives. I want your Field Engineer to last a lifetime and so have done everything possible to make it really live up to a tag line of Quality, Strength and Performance.

Total number of parts that make up a Field Engineer = about 770.