What problem does the stop lever (hack) actually solve?

[Stian]

Hi guys,

I understand that the hack stops the balance wheel when setting the watch. However, I don't really understand why this is necessary? Can anyone enlighten me?

Thanks,

Stian

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[Ishima]

Allows you to synchronize the watch seconds.  

Say in reality the time is 2:05:35 without hack you could set it to 2:05 easily, but if the watch is running, trying to get the seconds running on 35 is impossible.

Edited January 4, 2017 by Ishima

[clockboy]

Its also really handy on same watches such as a Rolex where the adjustment to the regulation is actually made via balance wheel rim screws & Chronographs when setting the hands.

[szbalogh]

And first of all the watch can be used as a chronograph, something military stuff  since one can start and stop whenever desired.

[rodabod]

It was important for military chronometer-grade watches.

Y'know, "Gentlemen, synchronise your watches", etc. In the early days of WW2, the Weems watch was used for navigation. This was non-hacking and used a simple bezel like you see on divers watches to set the "zero seconds" point. Later, the MoD specified watches to be hacking, such as the IWC Mk11, so they could simply be set to the exact time by halting the movement while adjusting.

[jdm]

11 hours ago, Stian said:

I understand that the hack stops the balance wheel when setting the watch. However, I don't really understand why this is necessary? Can anyone enlighten me?

If you are looking for "necessary" in horology, you're looking into the wrong industry 

[Stian]

Thanks a lot for the responses, very learningful. For non - chronographs though, does it not mean that every time you set the watch it also stops running? Probably not a big issue as such but probably not beneficial either?

Stian

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[Stian]

If you are looking for "necessary" in horology, you're looking into the wrong industry [emoji3]

Indeed, beneficial would be a better choice of words.

Stian

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