Join Date: Apr 2006
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A Rolex, like every "superb mechanical certified chromometer", is only certified accurate within two minutes a month.
A cheap quartz watch typically is within 10 seconds a month. Any of them.
A really good quartz watch, an adjustable one, can do about 15 seconds per year.
But any mechanical watch will need to be adjusted for the user's wear habits, which need to be consistent if the watch is expected to be consistent. The watch position (inside or outside the wrist) can change the rate by more than one minute per month. The position (12 up, stem up, etc) that a watch is left in overnight, if you don't wear it, can change the rate AND that's also a good way to modify the rate if you need to.
And then again, Rolex seems to say their watches need an annual cleaning and lube in order to run reliably.
I know the rate of my watches, more or less. One loses 15 seconds per month, which I call 1 second per two days, while the battery is good but that changes after a year. Another loses a bit more, but the battery is good twice as long. The Casio embarasses them both. But just for ****s and giggles I prefer to use GPS-time (which can need correction too, partly because it needs to be on for about 20 minutes in order to make sure it gets one full correction message from the network) with the sextant. Knowing I'm getting a time signal from a dozen or more atomic clocks...maybe $20 million dollars worth of CLOCKS giving me that time signal...How can you not laugh?
I'll hack a cheap stopwatch "on the hour" with the time, and then squeeze the "lap" button when taking a sight. That gives me a time which is pretty much identical to the moment of the sight, rather than trying to correct a bit more more for "look here, now look there", for what little extra precision that's worth.
Doesn't really matter what you use as long as it is a consistent timekeeper, worn or kept consistently, with the rate of gain/loss noted and known.