[alexiusmeinong]

Maybe I'm missing something, but here's a question that has been bothering me. Why do some chronographs like the Speedmaster and the Daytona have a 30 minute--rather than 60 minute--register? Suppose I time something and the hand of the 12 hour register reads 10, and the hand on the minutes register reads 15. How do I know whether what I timed lasted 10 hours and 15 minutes or 10 hours and 45 minutes?

 

[Black5]

Because the 12 hour register is progressive and doesn't just stay fixed on the hour.

^^ tells the truth on Internet forums

So many watches, So little time...

 

[Alysandir]

I believe the 12 hour register would read either 10 or 10.5, depending on whether 15 or 45 minutes had passed.

As to why 30 vs 60, readability. It's easier to see differences in time on a 30 minute register vs a 60 minute register.

Regards,
Alysaandir

 

[alexiusmeinong]

Thanks!