Hacking a Watch?

[Doofus]

If I wear a watch for a day, it will keep itself wound so that when I take it off, it'll have (let's say) 30hours reserve.

If I pull out the crown before putting it away, it will hack.

Is that bad for the watch? Can I pick it up a week later and use it as normal, already wound? Have I just invented perpetual motIon?

I know the time will be wrong, but is it bad for the watch to leave the spring in tension?

[CardShark]

I can't see why it would do any harm, I also can't see much point in stopping the movement running either. As you've said, the time (and date) will be wrong when you next wear it so you might as well let it run down when not on your wrist. Depending on your wearing habits you may also run the risk of accidentally damaging the movement in other ways, for example if you forget to push/screw the crown back in before taking a shower you increase the risk of water ingress.

[Doofus]

Just interested in the merits of keeping the spring wound...

[Lorne]

Doofus said:

Just interested in the merits of keeping the spring wound...

Always a debate, and you'll get equally good arguments/reasons for letting it run down or keeping it wound. On a technical level there's no merits in the spring being kept wound or allowed to run flat, but pulling the crown does open a potential path for dirt and dust ingress.