Marine Chronometers

Discussion in 'Chronometers' started by Paul Sullivan, Jul 27, 2012.

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  1. Paul Sullivan

    Paul Sullivan Registered User
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    Hi Guys,

    Let me say first of all that I'm a pocket watch collector. But I went to sea for 40 years starting in 1972. At that time celestial navigation was still the primary way of fixing the ship's position out of sight of land and deep ocean transit voyages. The ship was a reefer ship (Chirippo) built Stephen and Sons Shipyard in the UK in 1957. By the time I worked on her she was under Honduran flag (renamed OLANCHO)and still working for United Fruit Company, carrying bannanas to the States and UK. My post relates to a question about chronometers made in the UK about this time.

    http://en.wikipedia.org/wiki/Alexander_Stephen_and_Sons

    At that time the chronometers were still the heart of a ship's timekeeping and we carried two English models (although I can't remember the makers name). Both chronometers were key wind, but what made it unique is that one was connected by wires to a electric control box on the bridge. All the other clocks on the ship were electric and slaved off the signal from this chronometer. When you changed time zones you could advance or retard the electric clocks as needed and adjust the minutes for error also. Surprisingly, if you let the chronometer wind down (as I did once with a stern reminder from the captain) even though the slave clocks were electric, they would all stop. So I've recently wondered how the connection was made to to a mechanical clock. What I do remember was flipping it over, sliding the back plate over and winding it 7 1/2 half turns.
    Subsequently I worked on American ships, and with very few few exceptions all were fitted with Hamiltons and all the rest of the clocks were were key wind Chelsea 8 day with some being bell strikers (at the time we were still striking the 1/2 hour bells from the bridge to announce the watch time to the deck).

    Anyone have any idea of how the electrical connection worked? Was it like today's timegraphers with a microphone? Sorry I can't remember any details, but it was 40 years ago!

    Thanks for any input!

    Paul
     
  2. eskmill

    eskmill Registered User
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    #2 eskmill, Jul 27, 2012
    Last edited: Jul 27, 2012
    Welcome to the NAWCC Message Board Paul.

    At this time, I can think only of the Mercer "Octo" system used aboard maritime seagoing vessels that were originally launched in the UK. Mercer chronometers were widely used. Many were equipped with half-second electrical contacts that fed an electrical impulse to a master controller which controlled all the ship's clocks via a wire network.

    Only the ship's chronometer was set to GMT used for navigation. The cabin clocks reflected only mean local time.

    It is my understanding that the older ship-board clock systems were capable of adjusting all the secondary or slave clocks aboard either fast or slow depending on the course of the ship to compensate for gain or loss of longitude. Both Gent and Sychronome made sea-going master clock systems but I suspect the Mercer Octo system surpassed the older systems. All three shipboard clock systems, Octo, Gent and Synchronome incremented every thirty seconds.

    I have no knowledge of later systems but I am certain other contributors to the Message Board will have some more up-to-date information.
     
  3. Paul Sullivan

    Paul Sullivan Registered User
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    Eckmill,

    Thank much for you answer! Mercer definitely rings a feint bell in my memory! Your right about the chronometers; they were always set to GMT. Much like the railroads ships kept a zone or standard time. Each 15 deg. east or west of Greenwich meant adding or subtracting one hour to the ships clocks. When you crossed the 180th meridian on a Pacific transit you jumped 24 hours forward or back depending on your direction of east or west. Rather than change all the clocks each day at the noon observation and keep a daily mean time or local ship time, it made it much easier for watches and work on deck or the engine room to advance or retard one hour for every 15 deg. of longitude. Although the chronometers were still crucial as time keepers for celestial navigation, long before I went to sea, newer methods and simplified tables for the solution of the spherical trig. made the chronometers use as a (not so accurate) method of finding longitude obsolete.

    http://en.wikipedia.org/wiki/Longitude_by_chronometer

    I only worked on one other ship that had and electric clock/slave system. It was a Japanese ship built in 1981, a 96,000 dwt crude carrier. Unlike the Octo and other systems you mention, it was not connected to the chronometers. I worked on it in 1990 and it may have originally had a system like that but when I came aboard all that remained was the electric box control to the clocks. The chronometer was a trashy little Weems and Plath. When you took of the bezel the case was empty. Then you realized the movement was one of those AA powered black plastic things you see in todays cheap wall clocks. The attachment of the minute and hour hand was so shoddy and loose that you only got a guesstimate of the time.

    On earlier American ships built up to the early 1960's it was much different. We carried up to 26 Chelsea key wind 8 day clocks on the ship 6 of them were 8 day ship's bell clocks. The biggest was a large 8 day clock located between the throttles for the HP and LP turbines in the engine room control station. Prior to sailing or arriving the mate on watch would compare the minutes and seconds of bridge clock to the chronometer,note the error and call the engine room to compare their clock also and set the time to within 30s of each clock. At the time the company required that the bells recorded in the engine room and bridge bell books be taken to the half minute. The winding and setting of clocks in the offices of the captain and chief engineer, lounges, galley, chart room, engine room and bridge were the responsibility of the second mate. Keys were usually attached to the lower mounting screw to all the other clocks in officer and senior unlicensed cabins so they could wind their own and not be bothered off watch.

    Even today accurate time rules ship board life and although we no longer have decent chronometers we do have multiple GPS units and these show the most accurate time. All the Chelseas may have been replaced by cheap quartz watch models but they are still set by the new master clock; the GPS.

    Paul
     
  4. harold bain

    harold bain Registered User
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    I recall working on a master clock system on a great lakes freighter that was made by Simplex. It was a model 93 master clock, that used a crystal time standard board powered by a 12 volt battery, with wiper boards for contacts. It could have been either minute impulse slaves, or wired sync (can't remember which). I recall it was quite the adventure for this rookie repairman, a repair that had to be done quickly, and at night. This was around 1968 or so.
     
  5. Paul Sullivan

    Paul Sullivan Registered User
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    Harold,

    I'm sure it you had to be fast as no doubt they had to sail. I remember we sometime took repair techs. along after leaving the dock and we had a few hours to departure and they could finish the job. A laumch would take them off or they would leave with the pilot.
     

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