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teeteringhead
17th Apr 2012, 14:45
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.

So why the odd two minutes ???

Storminnorm
17th Apr 2012, 15:07
Someone had a Mickey Mouse watch?

Fareastdriver
17th Apr 2012, 15:10
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.

tony draper
17th Apr 2012, 15:16
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.
:)

teeteringhead
18th Apr 2012, 09:14
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: 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!)

tony draper
18th Apr 2012, 09:21
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.
:confused:

oops! google is your friend.:)
OTB - The First Wireless Time Signals To Ships At Sea (http://www.antiquewireless.org/otb/timesignals.htm)

M.Mouse
18th Apr 2012, 09:46
Someone had a Mickey Mouse watch?

Can't have been, my watch was not marketed until much later.

merch
18th Apr 2012, 12:11
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

RJM
18th Apr 2012, 14:15
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)

ThreadBaron
18th Apr 2012, 16:18
(uh-oh, deep waters)

More like an iceberg, if you ask me. ;)

ExSp33db1rd
19th Apr 2012, 00:13
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 !!

teeteringhead
19th Apr 2012, 07:27
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??

RJM
19th Apr 2012, 09:14
i dips me lid, teeteringhead. :ok:

teeteringhead
19th Apr 2012, 09:17
:O sfsg hjkklajksajaq iiiiouqioq

Mike744
19th Apr 2012, 10:06
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).

criticalmass
19th Apr 2012, 12:48
Mike 744 is spot-on.

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.

ExSp33db1rd
30th Apr 2012, 05:21
Titanic II

Aussie mining magnate Clive Palmer plans to building... | Stuff.co.nz (http://www.stuff.co.nz/world/australia/6830044/Aussie-mining-magnate-plans-to-build-Titanic-II)

sitigeltfel
30th Apr 2012, 06:41
Any takers for the maiden voyage? :ooh:

ExSp33db1rd
30th Apr 2012, 08:46
Any takers for the maiden voyage?

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 ?

Fareastdriver
30th Apr 2012, 09:15
RID (Irkutsk)

Do you allow for the 0.03 second that the signal takes to reach you?

merch
30th Apr 2012, 11:31
teeteringhead

The point I was trying to make, and failing dismally, was that the clocks which were two hours and two minutes out were the domestic clocks and probably nobody was all that bothered if they were a bit out. As some of my clocks in the house are. They weren't used for navigation so it wasn't important. Only adjusted so the punters didn't get confused with lunch time being at night.

criticalmass
30th Apr 2012, 14:13
Fareastdriver,

We never worried about delays due to propagation, our principal concern was accuracy to within 0.5 sec for celestial navigation purposes, mainly for timing sights. In fact, personal error using the sextant was greater than the error in time. When you are deep-sea, a celestial fix to within a couple of nautical miles of your actual position is amply accurate.

Fareastdriver
30th Apr 2012, 18:59
Pulling your leg, mate. I mentioned it because once sombody who supposed to be halfway around the world was talking to me on the telephone. I found him out because there was no pause beween our talking as the signal bounced from sat to sat.
He was still in the same country as I was and he should not have been.

ExSp33db1rd
30th Apr 2012, 21:12
So is that why I have that effect when talking to my mate a few miles away, if I use a local NZ clone of SKYPE to save paying extortionate toll rates ? Or is it just crappy Telecoms systems - a common NZ feature ? ( I have to carry two mobiles, Telecom and Vodaphone because neither have total coverage of the Country, and the West Coast of the Sth. Island has no mobile coverage at all, and I heard the other day that they are going to pay the new CEO of Telecom $1.35M later this year, and at the same time a family 15 miles from Tauranga, a major town, still can't be connected to Broadband. end of rant against NZ comms. sorry !! )