AquaDive 50 Restoration
Jeff, a friend of DeskDivers, had picked up an Aquadive Model 50. He needed it fixing and asked if we could help. Now DeskDivers don't usually take on outside restoration work, through a lack of time rather than ability. Due to other responsibilities we could never guarantee when it would be done and of course we’ve our own projects too. He was not worried about time, said ‘whenever’ would be a fine delivery date, shipped us the patient and work commenced...
The first challenge was getting the movement out.  A service manual was not available so the whole job would have to be done on instinct.
The Bourdon tube mounting screws and movement ring screws were removed, yet nothing budged. The collet around the pressure sensing case entry proved to be the solution. Gentle application of a suitably sized spanner got it to move. It is an interference fit, is sealed with an O-ring and mates with the Bourdon tube mounting block. Once it was out, everything became loose.
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Once the movement was removed from the case and dismantling began, the true extent of the flooding became apparent. It was horrible substance to mop up, the oil got onto everything and stunk out the office. Here are some pics showing the damage. The Fyrquel had soaked the movement, so much so that in places it had pooled into blobs.
With all components cleaned and ready, the rebuild commenced.
First the movement was rebuilt and oiled. A replacement NOS circuit and coil was installed, as the original was beyond repair.

This AD50 was picked up at a bargain price, but with good reason. The oil filling the Bourdon tube had leaked, flooding the case interior, and without stripping the watch it was difficult to assess the full degree of damage.
Initially things didn't look too bad, but as disassembly progressed it turned out to be a right old train wreck.
As was to be expected, the watch did not run. The most obvious cause being de-lamination of the coil and, ahem, over-oiling.
The ‘ Fyrquel ‘ oil is awful stinky stuff and is as aggressive as you would expect a type of hydraulic fluid to be. It had wreaked havoc.
The cause of the leak is circled in green.
There is, or rather was, a filler plug on the tube. The hole is threaded and the remnants of an O-ring can be seen.
It looks like someone thought it was a mounting screw and removed it, unfortunately they never put it back.
It was hoped that the dial had escaped the worst, initially the paint and printing seemed unaffected. Alas no.
The lume had absorbed the oil and one of the indexes (marked in green) simply slid off the dial! Thankfully it remained in one piece, so it was carefully cleaned and put aside for later re-attachment.
Because of the quantity of oil, a standard water based cleaning solution was not going to work. A more aggressive approach was needed and so cleaning proceeded first with highly refined paraffin, then naphtha and finally acetone for all metal parts. the dial and hands where meticulously dabbed with a tiny naphtha soaked pad under a microscope. they came up great and the fallen index was repositioned.
Amazingly, despite being soaked in oil and being cleaned using harsh chemicals, the hour and minute hands’ lume remained intact and in fine condition.
The only real victim was the depth hand, the oil had turned its fluorescent paint and white undercoat into putty, we asked for permission to strip and repaint it.
The okay to repaint the depth hand was received, so into the acetone and ultrasonic it went. Once done, we had a lovely shiny stripped hand.
To make the new coat of flourescent orange pop, a white base coat was needed. The white was applied and left to dry.
On with the orange fluorescent paint and the hand is returned to its former glory
Eagle eyed readers may have spotted an anomaly in the previous dial pictures.
An unfortunate case of not seeing the wood for the trees. In fact it was only whilst reviewing the photos that it became apparent. We've lost the ‘TI’ from ‘TIME-DEPTH’ on the dial.
The letters are usually obscured by the depth hand, the oil must have settled there in sufficient quantity to be able to attack the text and also the dial paint. You can make out a mark on the dial similar to the radium burn marks seen on old stopped and stored watches.
Even though the Depth hand covers these letters we needed to replace them for completeness.
The ‘wire’ laying on the dial in the photo above, is in fact a human hair which was used to paint the letters. The biggest problem (apart from the obvious microscopic scale of the job) was that, due to the tiny quantities used, the paint dries out whilst it is still being applied. Water based acrylic was chosen so that it can be removed easily should the dial ever be completely refinished.
Recreating the letters took a couple of hours, a lot of work for something no-one will see, but necessary all the same. While they look a bit rough under the microscope, with the naked eye they are quite acceptable.
The dial was re-attached to the now working movement, followed by the depth, hour, minute and second hands.
The carefully replaced letters once again disappear from sight.
The Bourdon tube was refitted, along with a replacement sealing screw and O-ring.
The freshly rebuilt movement was then reinstalled in the case and a new battery fitted so that the watch could be timed
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All-in-all this proved to be a fascinating experience. It allowed us an in-depth look into the construction and workings of a rare classic. Although we cannot promise to be able to help, should any reader have an interesting piece needing restoration, please feel free to contact us.
The mechanically restored watch was returned to its owner so that he could send it off for the final work required to return it to its former glory, that being case refinishing and crystal work. He was kind enough to send us photos of the finished article, here they are below.