Join Date: Nov 2007
Location: SF Bay area
Thanked 7 Times in 6 Posts
Rep Power: 10
When I play at CN (and it is just playing since eyeball navigation suffices around here), I use my (non-chronometer) wristwatch, which every once in a while I synchronize via the USNO clocks on the web. I don't set my wristwatch to GMT because it's a constant offset from GMT (though I sometimes forget to subtract the offset!).
I know you're supposed to know the drift rate of your chronometer so that you can estimate chronometer error and adjust the displayed time. So over a period of several months, at noon on Sunday I'd check my watch against the clock you can phone into, and record the error without resetting the watch. Unfortunately I've lost my notes, but I remember being surprised at how little it was, something less than 20 seconds gained over the whole period of several months.
My guess is that the errors you'd expect in CN are probably bigger than the errors that would be produced by using an imperfect watch. It would be an interesting exercise to compute the error in a noon sight if your watch is off by one minute. The sun moves a quarter of a degree per minute, iirc, so at the you'd be out by 15 minutes of longitude for every minute your watch is off, or a quarter minute for every second, or 5 minutes on my own wristwatch after several months of not resetting the watch.
The error might be greater if you're solving arbitrary navigational triangles, but I'll leave that as an exercise to the reader.
In the end what's important is that you have not only an estimate of where you are, but bounds on the error of your estimate. If I know that, at the equator, my watch could be producing up to five miles in error, then I have to keep five extra miles away from any hazards.
As for the radio, I'm not really sure how to get the signal. I have one of those cheap "world radios" that's supposed to receive from anywhere, I have tuned to the frequencies of the various time signals, but to no avail. I suspect that I'm using the wrong sort of radio for the purpose (maybe I need SSB or something), but in any case I'm stuck with my wristwatch.
s/v Laelia - 1978 Pearson 365 ketch