Sources of accurate reference time on board ?

[sarabande]

It would be a comforting feeling to have a really accurate source of time onboard without buying a certified and expensive chronometer.

I understand that digital radio is behind the times, as it were, but are ordinary wavelengths for medium and long still OK ? Do the pips still squeak on time ?

What about phones and internet sources please ? I have a feeling they may be subject to delay unless one signs in Mission Control in a bank.

I am playing ATM with an old one of those multi data weather stations that has a radio mast symbol. It seems OK but I am not yet sure of its rate, and how often it checks with the radio source.

 

[Lucky Duck]

GPS

 

[Spirit (of Glenans)]

Radio 4 Long Wave.

 

[Yngmar]

GPS, NTP (the protocol compensates for network latency) and a cheap Timex wristwatch that I bought because it can be used as a 15 minute on-watch nap vibration alarm. The crystal drifted only 15 seconds in a year, which I deem sufficient.

 

[cpedw]

Both the above or a radio controlled clock e.g. https://www.tlc-direct.co.uk/Products/CK74132.html
Then you won't have to mess about with it every spring and autumn.
Not sure about the range offshore of the radio signal but I'm sure it's 100s of miles from the Lake District.

Derek

 

[Spyro]

I would have thought you must have some sort of gps but if not and you have an internet connection http://www.thetimenow.com/

 

[lw395]

How accurately do you want to know?
You should start by working out the consequences of 'n' seconds error.
A quartz watch can be kept on your wrist and its error tracked against R4 over a period of months.
Generally the frequency drift reduces over the years, so keep the same watch and keep it at steady body temperature for best results.
If you are only reading the watch by eye, for astro, then there is the major part of a second's error in timing your observation anyway.
If you are timing something electronically, then you can get better crystals for better long term stability (a few parts per million), or Rubidium clocks are available (potentially good beyond parts per billion).
I once designed something that was stable to about 1/100th of a second over a couple of weeks using a Rubidium clock module. That's not state of the art, just doing a job on a budget.
GPS is of course broadcasting atomic clock time, but what comes out of the receiver is much degraded, often 'only' good to a fraction of a second.

 

[Norman_E]

On the Internet, this website: https://time.is/

 

[savageseadog]

Radio controlled clock

 

[Uricanejack]

A good watch or clock checked regularly. With a log kept of the error.
WWV 2.5, 5, 10, 15, 20 Mhz

 

[lw395]

Radio controlled clock

Radio controlled clocks tend to wander like any other quartz clock once you get out of reception. Because they are intended to get a correction signal daily, there is no imperative for them to have a particularly stable quartz crystal. And unlike a watch, they will be subject to the full temperature variation of the weather.
For practical purposes, logging the drift of a watch is the way to go, if you don't want to rely on GPS for time.

Or of course, if you know your location, you can use the sun etc. to tell the time.

 

[Richard10002]

It would be a comforting feeling to have a really accurate source of time onboard without buying a certified and expensive chronometer.

Why? And how accurate does it need to be to give you that comforting feeling.

 

[sarabande]

My trad brass clock face and movement has died.

I want a large (fairly crappy eyesight) display of hh:mm:ss preferably digital, but analog OK-ish, which is very reliable and preferably has a series of alarms, count-down and -up. A universal boat clock for nav, and watchkeeping purposes.

I really don't want to be taking the average air temp and compensating for rate changes, so lw395's v stable chip sounds really good. I would find such a paragon of a clock a comfort, being able to rely confidently on the displayed time, and not having to worry about corrections in the sight proforma.

I may try and build one from a Rasberrypi for fun, but the recommendation for Acctim clocks is useful.
http://www.acctim.com/Weatherstations/71753-Andreas--radio-controlled-clock-weatherstation

 

[Zing]

There are so many ways to get the time. I still one get why it needs to be remotely accurate? Even the crappiest watch or clock will be accurate to 20 secs a day. You don’t use a sextant I presume, so that’s good enough isn’t it?

 

[zoidberg]

There's something for everyone in this collection of over 200 stylish timepieces..... collections/swatch-and-art/

Here are a few samples.....

.... including one for the sea-fishermen!

 

[prv]

I still one get why it needs to be remotely accurate? Even the crappiest watch or clock will be accurate to 20 secs a day. You don’t use a sextant I presume, so that’s good enough isn’t it?

He mentions filling in a sight proforma, so I think your presumption is incorrect

Pete

 

[GHA]

WWV 2.5, 5, 10, 15, 20 Mhz

Has anyone ever actually managed to receive WWV in Europe?

 

[Neil_Y]

Buy two £20 Casio watches, they were easily good enough for astral nav.

I checked them against SW radio a few times but they were both accurate to within 1 second over 21 days.

 

[Neil_Y]

Has anyone ever actually managed to receive WWV in Europe?

Never used these but might try the old SW at home today and see what it picks up...

 

[sarabande]

Some watches can be really accurate, agreed, but it's the small size of the figures that present a problem. for a cabin clock. That's why I have been looking at digital wall clocks, and similar, rather than analog traditional.