I was tasked by a boat builder a little while ago to looking into how a unified 'ship time' was handled, distributed and displayed to crew throughout a larger vessel. I've found various systems and methods in use varying from a series of battery powered quartz clocks through to fully centralised time systems like the sort used for railway stations. I hope this post is worthy of discussion as I would be very interested to hear some feedback particularly from vessels that sail through different time zones and ports etc;
There can be a Ships Master Clock in the Wheelhouse and some slaves around the vessel elsewhere. These days a clock in the wheelhouse and as most systems that are on have a time indication the need to broadcast the info is no longer required as a stand alone system when folks have phones, wrist watches , radios that all show the time there is no real excuse for not knowing the time.
We're well past the days of sextants and noon-sites. Every crew member on my boat carries a smart phone and/or watch. I announce, via WhatsApp, at what time/day we are going to change the ship's time, and to which time zone they should set their phones. As an example today's order was: Sailing from Gibraltar at 1830, at which time we will set our clocks back to 1730. For smart phone users, please set your clocks to London time.