Wristwatch restoration, servicing and repair

Memosail Skipper (Valjoux Cal. 7757)…

It’s been quite a while since I’ve written about a sailing timer on the blog. This time it’s a Memosail Skipper.

(Click pictures to enlarge)

The Skipper model differs from the other Memosail timers I’ve written about in the past, as inside is a Valjoux cal. 7757; a sailing timer based on their ubiquitous cal. 7750 automatic chronograph.

There are various sources online claiming that the cal. 7757 was produced between 1985 and 1993, but ETA suggest that the calibre was discontinued in 1988, which probably explains the lack of production watches using this calibre. Apart from the Memosail Skipper, the only other watch I can find that uses the cal. 7757 is the Atlantic Skipper.

According to Juerg K. Bohne, managing director of Atlantic Watch AG, this watch was produced in conjunction with Memotime (the company who produce Memosail watches) and Dubois-Dépraz, the renowned chronograph specialists. He also suggested that in a short production run, just 300 of the Atlantic Skippers were made. I don’t know the number of Memosail Skippers that were produced, but given their rarity, I wouldn’t be surprised if it was a similarly low number.

Let’s have a closer look at the cal. 7757, starting with the components under the dial.

Removing the dial reveals the countdown disc, painted with the white, red, and blue sections that are visible through the holes in dial. The wheel takes 15 minutes to make one complete revolution, and like the cal. 7737 used in the other Memosail timers, it rotates continuously until the timer mechanism is disengaged (for a description of the cal. 7737, see here).

With the countdown disk and timer top plate removed, the heart of the mechanism is uncovered.

Here’s how it works. The driving wheel is mounted on the extended axle of the third wheel in the going train, and provides the power to the countdown disc via the two intermediate wheels. When the timer is started using the start/stop pusher, the detent rotates and simultaneously releases the brake from the gear mounted on the underside of the countdown disc, and using the actuating lever, engages the intermediate wheel with the same gear, and the countdown disc starts to rotate clockwise.

When the timer is stopped the reverse happens, the intermediate wheel is disengaged, and the brake applied to hold the countdown disc steady in it’s current position.

On the train side of the movement, just like a standard cal. 7750, the centre chronograph wheel is engaged when the timer is started, and the centre second hand sweeps around the dial.

There are subtle differences from the standard cal. 7750 though, namely that the minute recording wheel in the 7757 is used solely to perform the reset function, and so has no teeth (see inset). This timer in this calibre doesn’t ‘tick’ forward in 30 second intervals like the cal. 7737, as the timer is driven directly from the wheel train, it is in constant motion when engaged.

When the reset button is pressed, just like a regular 7750, the reset lever moves across to return the reset hammers back to their starting positions. On the dial side of the movement, as the reset wheel is mounted onto the axle of the minute recording wheel, it also returns the countdown disc back to it’s starting position – showing 5 white dots on the dial.

The watch in this post arrived in running condition, but would stop immediately as soon as the timer was engaged. Further investigation revealed that the oil on the timer mechanism had thickened over the years and the increased friction was enough to stop the movement altogether. A full service for the movement immediately put things right.

If anyone has any further information about the cal. 7757, or other examples of watches using the calibre, it would be great to hear from you.

Rich

** Many thanks to Stephen Giles for letting me feature his watch on the blog, and to Mark Reichardt for additional background information about the cal. 7757. **


One Response to “Memosail Skipper (Valjoux Cal. 7757)…”

  1. Patrik Ström Says:

    I have a Memosail start watch with the Valjoux 7757 calibre. The dial is very similar to the Atlantic Skipper. The bezel is slightly different with both degrees 0 – 360 as well as cardinal “bearings” like N, NNE, NE, ENE etc with the result that it is almost impossible to read the degrees or the cardinal marks without a pair of bioculars… The bezel on the Atlantic is a lot better. The case is – unfortunatelly – goldplated stainless steel

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