My question regards the status of self-winding mechanical watches on shabbos/yom-tov. Is it permisible to wear a self-winding watch (that winds as a result of the movement of your hand) on shabbos/yom-tov? Let me know you thoughts. Thanks in advance.
It is permitted to wear a self-winding watch on Shabbos.
Many poskim forbid actually winding a watch on Shabbos, because is might be considered “fixing a vessel,” or, according to the Chazon Ish, an act of “building.”
In the case of a ticking watch that is already ticking neither of these reasons apply, and the Da’as Torah 338:3 writes that the custom is to be lenient to wind an already ticking watch. Moreover, there is room to argue that even for a stopped watch there is no prohibition of winding the watch, because a stopped watch is not “broken.”
However, the Mishnah Berurah (338:15) is stringent even regarding winding a ticking watch, and this is the accepted custom (see Shemiras Shabbos Kehilchasah 28:19), unless there is an urgent need.
Yet, based on the above there is surely no problem in wearing a self-winding watch while it is ticking, for no active action is being done. See also Shemiras Shabbos Kehilchasah (28:28) who is lenient in this matter, and sources cited in the footnote.