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Presumably when you are at sea you either have a GPS (where we tape over
the L/Lo display and simply look at the time, of course) or a short wave
receiver that can receive WWV.   I wouldn't go to sea without both.

As I recollect, the beginning of the thread was how one could get
accurate time without a SW receiver.   Although I don't recall it being
explicitly mentioned, I think the context of the question implied "on
land in the continental USA"

I also wouldn't go to sea without measuring the watch rate of whatever
timekeeper I was proposing to use, so I'm not sure I'd need "twice
daily" calls to Ft. Collins.   I've found cheap Timex or equivalent
quartz watches to be remarkably good timekeepers (at least on my wrist,
I've never taken them off and subjected them to freeze-boil cycles) --
if given the chance to measure watch rate, I'd be pretty confident of
going for a month or even more without cross-checking with WWV or
equivalent.

Lu Abel

james whitson wrote:
> Unless you are near a port, there is no cell phone reception at sea.
> Even in the Great Lakes, my cell has proven to be extra baggage. Sat.
> phones are better, but the "minutes" are steep. May I suggest that,
> for navigational purposes, you call Ft. Collins, CO and reset your
> time-measuring device twice daily.-Jim
>
> > From: danallen46@airwired.net
> > To: NavList@fer3.com
> > Subject: [NavList 4917] Re: Time and cel nav, a stupid question
> > Date: Tue, 22 Apr 2008 23:43:46 -0600
> >
> >
> > It turns out my AT&T iPhone is slow as well!
> >
> >
> >
> > On Apr 22, 2008, at 5:07 PM, Fred Hebard  wrote:
> >
> > >
> > > Dan,
> > >
> > > The Mac is fine. It's the AT&T cell phone that's slow!
> > >
> > > Fred
> > >
> > > On Apr 22, 2008, at 6:52 PM, Dan Allen wrote:
> > >
> > >>
> > >>
> > >> On 22 Apr 2008, at 4:26 PM, Fred Hebard wrote:
> > >>
> > >>> On a Mac, using time.apple.com. Just synced, and still about 50
> > >>> seconds slow.
> > >>
> > >> That's very unusual. I sync lots of Macs to time.apple.com and I am
> > >> never off more than 10 or 20 milliseconds, according to the Mac
> > >> Terminal command
> > >>
> > >> ntpq -c peers
> > >>
> > >> which shows details of NTP servers and times. I have tweaked my /
> > >> etc/
> > >> ntp.conf file so that I can query several different servers and NTP
> > >> figures everything out.
> > >>
> > >> Here is a sample output of the ntpq -c peers command on my main Mac:
> > >>
> > >> ---
> > >>
> > >> remote refid st t when poll reach delay
> > >> offset jitter
> > >> =
> > >> =
> > >> =
> > >> =
> > >> =
> > >> =
> > >> ===
> > >> ===================================================================
> > >> ==
> > >> *clock.xmission. .GPS. 1 u 614 1024 377 24.369
> > >> -8.786 6.633
> > >> -time1.apple.com 17.106.100.13 2 u 19 256 377 38.468
> > >> -5.278 34.007
> > >> +time-b.nist.gov .ACTS. 1 u 419 256 376 88.355
> > >> 8.279 27.296
> > >> +tick.usno.navy. .USNO. 1 u 255 256 377 97.773
> > >> 10.332 19.811
> > >>
> > >> ---
> > >>
> > >> It shows four different servers that I am checking in with. The
> > >> offset column is in ms and shows how far from those servers my
> > >> machine
> > >> is. The delay column shows the distance in ms to these servers. The
> > >> jitter column combines errors in propagation along with absolute time
> > >> errors to come up with an overall error figure, also in ms.
> > >>
> > >> Dan
> > >>
> > >>
> > >>>
> > >
> > >
> > >
> > > >
> > >
> >
> >
> >

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