Sources of accurate reference time on board ?

Re: Sources of accurate reference time on board ?n

I have my dads old stainless rollex somwhere. I have always worried about loosing it so I used a fake from Taiwan with an automatic Seiko movement. It died now have a Seiko 5
Also have a quartz one but they run out of battery and it’s anoying
They have solar ones now I might get one.

As Minn said 1 minute of long every 4 seconds I tried from 1 second Accuracy

I would work my position out to the nearest whole minutes of lat and long
 
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For those of us with an interest in traditional (pre transit pre gps)navigation we need an accurate time signal source.
The bbc world service time pips on the internet are delayed - several secs, look it up.
I cannot get WWV and I do not have a receiver for long wave bbc time pips reception which would be accurate.
How about www.time.is? I have just checked time.is against a gps - it was 5 secs behind. I think the gps time is ok for sights.
I miss the days of 'sparky' putting the Rugby time signal through to the bridge every day for checking the chronometer.
Michael.
 
GHA said:
Must have been very good propagation.

I've never heard a whisper, even in an empty anchorage.

http://www.websdr.org/

Nothing heard..


Seems exciting enough to post to youtube when it does get through

https://www.youtube.com/watch?v=Rm7wq4kes2I
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I think It was because I had a very good radio. Sony ICF 7600. Multi band digital with an extended antenna.
I am currently in Glasgow, found an old radio tape player with a short wave band No luck.
I looked and you can get cheep Chinese Radios with short wave bands. have one my boat which along with the old Sony are at home in BC. So I cant test it.

I cant find any New Sony SW Radios for sale. E bay has a Few ICF 7600.

I guess the bottom line is most folks are happy with GPS for time and nobody bothers to listen much to SW. I think the BBC WS still broadcasts but its very hard to receive in western Canada or US. So I haven't bothered to try and tune in for decades.

I don't sail offshore anymore. I haven't been out of sight of land for about 30 years. Back in the day, I used to regard a good SW radio as a prised possession. To listen to the outside world it wasn't just so I could get a time signal. I was so I could always hear the BBC. Times change I suppose its possible to get satellite radio internet making SW virtually obsolete. MW just does talk radio where I live. . FM is good in town only. I don't know if there even is a long wave station now. Do people who head offshore today, bother with a good radio? I wouldn't know.
 
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Uricanejack said:
I guess the bottom line is most folks are happy with GPS for time and nobody bothers to listen much to SW. I think the BBC WS still broadcasts but its very hard to receive in western Canada or US. So I haven't bothered to try and tune in for decades.

I don't sail offshore anymore. I haven't been out of sight of land for about 30 years. Back in the day, I used to regard a good SW radio as a prised possession. To listen to the outside world it wasn't just so I could get a time signal. I was so I could always hear the BBC. Times change I suppose its possible to get satellite radio internet making SW virtually obsolete. MW just does talk radio where I live. . FM is good in town only. I don't know if there even is a long wave station now. Do people who head offshore today, bother with a good radio? I wouldn't know.
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Probably not that many arguments to having an SSB receiver in Europe. Maybe handy for weatherfax or DWD RTTY in the north sea. A good lower budget option is the Degen 1103 , very good receiver but not the best button and menu design ever.
I have 3 radios onboard, trusty Degen which provided weatherfax across the Atlantic just attached to a masthead FM broadcast antenna - before I knew anything about radio waves :)

Also a high quality fun cube dongle pro plus USB receiver, goes from something like 150Hz up to near 2Ghz. Unfortunately I can't quite get the always on Raspberry Pi to run this without an occasional stutter which messes up weatherfax, played very briefly with GNU radio software so might be able to get some very basic receive direct to a sound file going, automated weatherfax reception offshore would be just wonderful. Offshore as in out in the ocean, not across Lyme bay ;)

Then the big boy is a Icom IC7000 ham transceiver. Very good piece of kit. :cool: Playing with WSPR weak signalk reporting system I've been picked up in Australia with under 10w of transmitting power. Also means free (small and slow) emails anywhere, great for gribs offshore, and has probably easily paid for itself in the savings on sat phone sim card line rental alone. For ham offshore you need the full advanced ham license, not expensive and very educational.

Cruising away from Europe SSB & Ham afloat is very much alive and well, dozens of regular nets every day and must be many more ad hoc nets with boats doing a crossing keeping in touch. Sat phone is common but the airwaves are very far from dead.
 
Joshua Slocum circumnavigated with an old alarm clock which he bought for a dollar and only had one hand. These days, any old quartz clock or watch will keep accurate time down to seconds per year so no need to spend a fortune.
 
I have a Waltham pocket watch which I think belonged to my grandfather although I don't remember him carrying it. It dates from 1903 so is the same age as my house, Edwardian. It's a lovely thing and runs but gains a lot so is useless for timekeeping. It needs cleaning to restore accuracy which would cost more than its worth (about £50 so will never be done. My son will have it after me who will probably also keep it in his sock drawer.
Minn said:
Page 208 of Hiscock’s “Voyaging under Sail”, showing the classic yachtsman’s noon fix.

Note the 41 seconds on the stopwatch (clicked when the sun was “on” and used to transfer time to the deck watch (a Waltham, in his case)) and the accumulated error of 3 minutes 15 seconds fast on the deck watch based on the time signal.

He was comfortably close to his DR position.

image upload no resize
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All these electronic means of getting the time are no use if you need to rely on time for back up navigation using a sextant. Your gps and spares will most likely be only taken out if you are hit by lightning. That will also take out the radio and quartz timepieces. Best invest in a good old fashioned mechanical watch. It can be a thing of beauty and wonder too.
 
Uricanejack said:
I think It was because I had a very good radio. Sony ICF 7600. Multi band digital with an extended antenna.
I am currently in Glasgow, found an old radio tape player with a short wave band No luck.
I looked and you can get cheep Chinese Radios with short wave bands. have one my boat which along with the old Sony are at home in BC. So I cant test it.

I cant find any New Sony SW Radios for sale. E bay has a Few ICF 7600.

I guess the bottom line is most folks are happy with GPS for time and nobody bothers to listen much to SW. I think the BBC WS still broadcasts but its very hard to receive in western Canada or US. So I haven't bothered to try and tune in for decades.

I don't sail offshore anymore. I haven't been out of sight of land for about 30 years. Back in the day, I used to regard a good SW radio as a prised possession. To listen to the outside world it wasn't just so I could get a time signal. I was so I could always hear the BBC. Times change I suppose its possible to get satellite radio internet making SW virtually obsolete. MW just does talk radio where I live. . FM is good in town only. I don't know if there even is a long wave station now. Do people who head offshore today, bother with a good radio? I wouldn't know.
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I have a Sony ICF SW77; it's more than twenty years old now having accompanied me to sea, for five years in China (yes, it got the World Service reliably) but it needs a service if such a thing were possible. Sony seem to have stopped making it, but there is a rather similar one made by Tecsun in China - the PL880.
 
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emandvee44 said:
For those of us with an interest in traditional (pre transit pre gps)navigation we need an accurate time signal source.
The bbc world service time pips on the internet are delayed - several secs, look it up.
I cannot get WWV and I do not have a receiver for long wave bbc time pips reception which would be accurate.
How about www.time.is? I have just checked time.is against a gps - it was 5 secs behind. I think the gps time is ok for sights.
I miss the days of 'sparky' putting the Rugby time signal through to the bridge every day for checking the chronometer.
Michael.
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Two issues here. First, Internet derived time can be pretty accurate - better than a second - but you have to use a server supporting the NTP protocol. NTP allows for correction of latency on the internet connection. A laptop or PC can easily be set up to use a NTP server to keep its clock correct, which it will do with sub-second accuracy providing you select an appropriate - most ISPs provide it, and there are many public servers, although these can be over-subscribed (in the Bad Old Days, Microsoft ALWAYS pointed their NTP software at a server in Seattle!). There are web-based services; see https://nist.time.gov/ for example, which corrects for path delays. However, you have to be in reach of an Interbet connection to use it. At home, I always assume my PC's time is accurate.

Second, GPS is easily the most accurate time-source available to us. However, that accuracy may be degraded by priority in navigational devices being given to position fixing. A navigational GPS' display time may be up to 2 seconds off. To obtain the full accuracy of GPS time requires a specialized receiver; that is used in places where it REALLY matters, such as in timing transactions on Stock Markets, where milliseconds can make the difference between a profit and a loss!
 
It seems to me that if you are going to use your GPS to provide you with accurate time info to then input into your astro nav calculations to derive your position, you might as well take your position from the GPS and save yourself the trouble.
As others have said, if you're mid ocean, it doesn't matter so much that you get a precise fix.
 
ghostlymoron said:
It seems to me that if you are going to use your GPS to provide you with accurate time info to then input into your astro nav calculations to derive your position, you might as well take your position from the GPS and save yourself the trouble.
As others have said, if you're mid ocean, it doesn't matter so much that you get a precise fix.
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One of the problems on a long passage is always finding something to do, so using trad. nav. is one way of filling the time, and then there is the theoretical possibility of losing all electronics, thanks to a lightning strike or suchlike, which is why some of us always keep a spare old GPS in a tin box.

It would also be fair to say that given the sorts of voltages and amperages involved in a lightning strike, if the electronics are all fried there seems to be a very good chance that the balance spring of a mechanical watch will also be affected by the magnetic fields generated.

More important perhaps is Hilaire Belloc's observation, quoted by HW Tilman:

"In venturing in sail upon strange coasts we are seeking those first experiences, and trying to feel as felt the earlier man in a happier time, to see the world as they saw it."

After all, nothing goes to windward better than an Airbus A 380, but we still mess about in boats.

6_B5_C8566-66_C4-42_AA-98_A9-_C39_DE53977_C4.jpg
 
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I agree it's a good way to fill time. It typically takes me about half an hour to reduce a reading. I don't do it very often so practice would reduce that a lot.
 
ghostlymoron said:
I agree it's a good way to fill time. It typically takes me about half an hour to reduce a reading. I don't do it very often so practice would reduce that a lot.
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From what little I remember, two seconds error will put you half a mile out. Although unnecessary error should be avoided, it should be little enough for you to avoid the Isles of Scilly.
 
Some, more specialised GPS receivers will output a 1PPS time sync. This consists of a short 5v or 12v pulse, typically 1 msec in duration each second. The other element is a time message, typically NMEA GPZDA which provides the time associated with that pulse. This combination will easily provide less than 1msec error and is very reliable.
 
I don't see why you need a super accurate time source if you have a working GPS - that will give you your position directly.
richlear said:
Some, more specialised GPS receivers will output a 1PPS time sync. This consists of a short 5v or 12v pulse, typically 1 msec in duration each second. The other element is a time message, typically NMEA GPZDA which provides the time associated with that pulse. This combination will easily provide less than 1msec error and is very reliable.
Click to expand...
 
It would appear that the easiest way to get a good time standard (independent of GPS) is a reasonable quartz watch (e.g. a casio) but that this is not ideal for the OP as they would prefer a bulkhead mounted (digital?) clock.

Perhaps the solution could be to have a master watch and a slave clock display. This would allow the OP to select their preferred display, regardless of how well it keeps time, as it would be synchronised with the master every morning. Obviously this introduces an extra daily task, and there is a risk that the OP forgets to synchronise, resulting in incorrect timings.
 
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