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"Ship's Time" on Titanic
I know the last thing the world needs at the moment is more on the Titanic, but I thought JB can usually answer the most obscure questions quickly.
It appears that Titanic's clocks were set nearly 2 hours ahead of EST (actually 2hrs 2 mins) or - if you prefer - nearly 3 hours behind GMT (actually 2 hrs 58 mins).
My question - why the nearly?
I always understood (from old merchant seamen!) that crossing the pond in "the old days", taking 5 days, they simply put clocks back (westwards) or forwards (eastwards) by one hour exactly in the early hours of each morning.
Net result: a seamless transition from GMT to EST (or vice versa) and no "jet lag" or similar.
The deck officers would have taken their sunshots at midday and the shot that was highest would have been the local midday. The clocks would have been set to that. There were no other time references on board as GMT and all that had yet to be used for wireless operations and the passengers mobile phones would not have worked.
Second Mates Job to flog the clock in my day,probably only four aboard the ship so no big task,Titanic probably had dozens of the buggas one in every public space,mebee they were electrical run from one Master Clock.
Location: uk mostly, desert lots, searching for lost posts
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Quote:
The deck officers would have taken their sunshots at midday and the shot that was highest would have been the local midday. The clocks would have been set to that.
... thanks Fareastdriver, I'll buy that. After all, that's how we all set time until the bl%%dy trains arrived and we had to have the same time in London as in Bristol.
But I won't buy:
Quote:
There were no other time references on board as GMT and all that had yet to be used for wireless operations and the passengers mobile phones would not have worked.
(Apart from the mobile 'phones bit!) Surely the ship's chronometer would have read an accurate GMT (established as a reference by the International Meridian Conference in 1884), in order to calculate longitude.
And interestingly (sic), at the time of the sinking the Equation of Time would have been nearly zero (zero on 15th April for epoch 2000 - not sure about 1912!)
By the time of Titanic wouldn't there have been a Noon GMT signal broadcast from London for shipping? would have thought that would have been one of the first ideas thought up with the advent of wireless.
The clocks that are changed are the clocks in cabins, public rooms etc. The Chronometer will always be on GMT (UTC). As the ship progresses west the "public" clocks are adjusted, with two main purposes in mind, the first is so that the clocks are on local time when the vessel arrives in New York. The second is so that local noon occurs near to 12:00hrs on the ships clocks. Some Masters adjust the clocks half an hour at a time and some an hour at a time. To adjust the numerous clocks on the ship, as Tony says, it is either done by means of a Master clock being adjusted which will adjust slave clocks. Or some poor sod wanders round the ship doing it manually. In either case there plenty of scope for error in adjusting the clocks. The master/slave clock system is prone to the slave clock not following the Master clock correctly, and the poor sod wandering around the ship is prone to many more errors. The Chronometer is the only clock for Navigational use. So in my mind the the 2 minute error is not of any significance. Hope that helps
And interestingly (sic), at the time of the sinking the Equation of Time would have been nearly zero (zero on 15th April for epoch 2000 - not sure about 1912!)
teeteringhead, the zeros in the equation of time (one of which is at approx April 15) are always in the same place on the calendar. As I understand it, the equation of time is a variation due to the annual eccentricity of the earth's orbit and its values don't accrue, diminish or drift from year to year. They relate to annual solar time, and aren't affected by the occasional adjustments we make to 'absolute' time. Although our absolute time must be arbitrary in relation to the universe's time... (uh-oh, deep waters)
Crossing the Atlantic 44 years after the Titanic, with my 12 RAF mates, we discovered that two brass screws visible under each clock could be bridged with a penknife (remember those ? ) which advanced that single clock by one minute at a time, so on a 10 day crossing, instead of all the clocks being advanced automatically from a central control every second day, in the middle of the night we crept out and moved half the public clocks back one hour each night.
Chaos reigned, people turning up for breakfast, lunch or dinner one hour early, or late.
Magic ! Such Fun !!
Last edited by ExSp33db1rd; 21st Apr 2012 at 21:53.
Location: uk mostly, desert lots, searching for lost posts
Posts: 2,208
Up to a point RJM. Eccentricity of orbit is one factor, the inclination of the Earth's axis being the other (obliquity of the ecliptic to be technical). It's the sum of these (more or less) sinusoidal errors that give the E of T curve its shape with two peaks and four zeros. And apart from minimal changes in those factors, 1912 was a Leap Year, so had already had its extra day.
merch I get your point about changing the clocks by half an hour or an hour so that clock noon is fairly close to sun noon ........... but I still don't get the "odd" two minutes. As "ship's time" is essentially a pragmatic appoximation (as any "mean time" is), why change it - as they must have done - by other than a round figure??
As a Radio Officer in the Merchant Navy it was necessary to route an official (WWV etc) time signal to the bridge by loudspeaker at least once per day. The bridge noted the difference between the bridge chronometer and the time signal in a logbook. (i.e. the chronometer was not manually corrected, just the time difference recorded).
In my time at sea as an R/O I used to send the time signal to the bridge at noon, just before signing off on my morning watch. The Mate on watch would compare the time on the ship's chronometer(s) and note the difference in the Chronometer Rate Book, which was kept on the chart-table for reference.
At deck-survey time (i.e. annually) the error would be corrected and the chronometer re-set, usually with a change of batteries. A set of batteries (usually multiple D-cells) would last the year and some chronometers had a backup battery to power it during a change of batteries (e.g. Seiko QM-10) or had double sets of batteries (Wempe and Glashutte Type 1-71) where you changed one set at a time and the chronometer kept running whilst each set was being changed. These were high-precision temperature-independent quartz chronometers and their rate was small and constant. I have four such chronometers and the best rate-keeper of the lot is a Seiko QM-10 which is 0.5 sec fast after 564 days.
Off the Aussie coast I used VNG from Lyndhurst, when we were deep-sea then WWV, WWVH or RID (Irkutsk) were usually receivable under most conditions.
These chronometers were set into recesses in the chart-table, usually with a glass cover to allow the dial to be read without disturbing the timepiece.
Wonder if they'll follow the same route across the pond ?
Shouldn't worry, Global Warming will ensure softer icebergs.
If they follow the specs. precisely, will they also go with insufficient lifeboats for all the passengers ?
Will they make the woman wear those silly hats ?
bet they take more than one pair of binoculars ( just seen the latest film on local TV - which I reckon wasted two Sunday evenings - not impresssed )
If it's to be built in China, how can its' Maiden Voyage start in England ? or is it only called a Maiden Voyage when fare-paying punters are on board, all previous voyages being 'sea trials' ?
Blue Star Line ?? Is that a merger of White Star and Alfred Holt ?
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