>> Don't know if this applies but SOME ships have/had floating
>> mains systems with neither side earthed. Could make life
>> exciting construction wise
>
>The ship's engineer has faxed that the mains is produced by
>"a standard method", his words, varying from 58Hz to 61Hz
>Re: [EE]: Replace old chips ?

Means they're using a standard motor-generator with its controller. Forget
about that as a clock source.

Imvho you could gamble and make a simple clock with a PIC and use a TCXO
or an ovenized XO off the shelf ($40 to $150) which will buy you 0.5ppm
(15 seconds per year deviation, or 1+ second/month), unadjusted, and
better adjusted - but you prolly don't have the means for proper
adjustment at that precision range since you're asking. You could add a
NMEA (GPS) stream to set the clock once in a while. (I suspect that the
readout displays show seconds at best so aiming for cesium clock accuracy
will be slightly overkill).

I think that the (old ?, mechanical) naval chronometer standard requires 2
weeks or running reserve and 1 second deviation per month. If you match
that you can probably call it a uncertified naval chronometer and not be
sued too (but check my numbers...).

Peter

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