What are hacking seconds?
A hacking watch stops its seconds hand when you pull the crown out, so you can set it to the exact second. How to tell if yours hacks, and how to set one that does not.
Published
What it means
On a watch with hacking seconds, pulling the crown out to set the time stops the balance wheel, so the seconds hand stops. Push the crown in and it starts again. That lets you start the watch on the exact second.
The name is usually traced to military use, where crews synchronised their watches before an operation.
Does yours hack?
Pull the crown all the way out and watch the seconds hand. If it stops, the watch hacks. Most current Swiss and Japanese movements do, including the ETA 2824, Sellita SW200, Seiko NH35 and 4R35, and Miyota 9015. Some popular movements do not, including the Seiko 7S26 in the SKX007 and SNK809, and the Miyota 8215.
Setting a watch that hacks
Pull the crown out when the seconds hand reaches 12, set the minute hand a minute ahead, and push the crown in when the sync countdown reaches zero. The full guide has the details.
Setting a watch that does not
- Watch the seconds hand and the countdown together, and note how many seconds apart they are.
- Set the minute hand so that it lines up with the minute marker as the watch's own seconds hand passes 12.
- Push the crown in. You will usually be within a few seconds, which is all a non-hacking watch is built for.
Is hacking bad for the watch?
No. It is a small lever resting on the balance wheel, designed for it. Just do not leave the crown pulled out for long, especially near water or dust.