Boxhall's reworking of the CQD position

Rob Lawes

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Jun 13, 2012
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I should know better than to address subjects about which I know nothing, but did Smith himself work out Titanic's position that night, or just Boxhall?
Boxhall spent the evening plotting the set of star sights taken by the 2nd Officer at around 19:30.

Smith worked up the initial distress position presumably based in part on the information provided by Boxhall and by dead reckoning.

Immediately after the first distress messages were transmitted Boxhall worked up a slightly more accurate position which was then provided to the Marconi room and transmitted in all subsequent messages.
 

Jim Currie

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Apr 16, 2008
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Hi Jim,
What is wrong speculating on Murdoch mind? After all there is lots more speculating of the Titanic last movements as the log book and chart maps are all loss with the ship, making a difficult task to sort out and trying put together what exactly happened that night and probably never ever know 100% for sure. Speculation indeed!
I am trying to understand why such an experience captain as Smith has got the navigation position wrong followed by Boxhall too?
I just get the feeling Murdoch knew (speculation if you like) there was some was just quite right by smell the ice comes to mind! But he was stuck in that position having to carry out the Captain order. Come to think about it why hasn't Murdoch work out the position too?
Hello Mike.

There is absolutely nothing wrong with speculating about an historical event, if the result of such speculation begins with "What if?"
The problem on this site and many others is that Eurika! and "Ah! That's what happened then." moments, are often developed into historical fact.

If you understand what was going on at a moment in time or can clearly visualize a description of what was going on at that time, then there is no need for speculation. Suitably qualified individuals more easily visualise missing connections.
For example...following a great flood, road re-construction teams can easily visualise a missing bridge.:rolleyes:

Technical re-construction of the evidence given by Boxhall and Smith shows that Smith was simply fed improper data and Boxhall made the wrong assumptions regarding speed and steaming time.
However, these reasons will not be accepted by those who revel in conspiracy theories or who start with an answer, work backward and while doing so, reject important evidence which does not fit.
Why should we be surprised at such an approach, when professionals in the shape of Captain Knapp USN and Captain Rostron of the Carpathia blatantly bent the truth to suit the occasion.
 

Jim Currie

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Boxhall spent the evening plotting the set of star sights taken by the 2nd Officer at around 19:30.

Smith worked up the initial distress position presumably based in part on the information provided by Boxhall and by dead reckoning.

Immediately after the first distress messages were transmitted Boxhall worked up a slightly more accurate position which was then provided to the Marconi room and transmitted in all subsequent messages.
Small correction:
According to Boxhall, Smith used the 8pm DR position as the starting point to calculate his distress position. Also, according to Boxhall, that 8 pm Position was 20 miles out.
The 8 pm DR position was calculated by 5th Officer Lowe. To do so, Lowe would have used 3rd Officer Pitman's DR for use with Lightoller's sights
Coincidentally, Captain Smith's distress position is also 20 miles out. Admittedly in the wrong direction from that given in Boxhall's 1962 BBC interview, but 20 miles never-the-less.
In fact, Boxhall had nothing to do with the 8pm DR and no reason to consult it at any time.
 

Mike Spooner

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Jan 31, 2018
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I should know better than to address subjects about which I know nothing, but did Smith himself work out Titanic's position that night, or just Boxhall?
Hi Mark,
I would agree with you a person like me who is not a navigation and looking into as an outsider point of view.
I have now had the time to read Jim Currie article: Re-Opening Can of Worms. First I do respect Jim as a experience professional seaman and contributed an enormous amount into ET. My personal congratulation to him.
Reading his article I am quite shock to see so many officers and captain are making mistakes after leaving Queenstown. I am thinking this is the cream of the crop officers and yet Atlantic crossings are nothing new to them either.
So I am going back to the navigation equipment and was it giving correct reading at the time? If not it doesn't how many times Boxhall recalculate the position he will get it wrong.
Now with your little help from you experience seamen. If the ship leaves Belfast, Southampton, Cherbourg and on to Queenstown. Would I be right to say like land references: Hill tops, Lighthouses and buildings are a good guide for navigation? As at this stage things like compass, chromite clock, sexton, RPM, stars and sun etc are not the bees knees for dead accuracy.
However when leaving Queenstown you are now on your own in the Atlantic with no land reference as guidance were now the dead accuracy of navigation equipment is required? True or false!
 
Dec 4, 2000
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Dead reckoning is just a method of recording a ship's movements between fixes using its "run" from the starting fix. The "run" i was calculated on duration (aka "time"), speed, and direction. In 1912 the process was done using the methods of traverse sailing which originated as ships began making extended offshore voyages. The instruments necessary for dead reckoning were something to measure speed (taffrail log) an ordinary clock, and mariner's compass. The compasses in Titanic could be read to 1/2-degree accuracy.

Pencil and paper were also needed. Data recorded during the run would be combined mathematically into a lat/lon position.

It was never intended for dead reckoning to be perfectly accurate. The DR is expected to be "off" compared to a fix taken for the same moment in time. This is not an error as such, but rather the inevitable result of wind and current. Comparison of the fix to the DR allows the navigator to determine the set and drift caused by these natural forces.

A "fix" is a lat/lon position based on either observation of fixed objects ashore (best) or on stellar observations at sea (less accurate). A minimum of two observations of fixed objects and three is considered the "gold standard." each observation produces a line of position, or LOP, based on the true compass direction from the ship to the object. These lines of position are plotted on a chart, the ship's position is taken as where they cross. Or, more likely inside the small triangle (called a "cocked hat") produced by their crossing.

Even though highly useful, fixes were not perfectly accurate. For instance, assuming it took the navigator of Titanic 6 minutes to obtain the bearings or celestial observations for a fix. At 22 knots this would mean that the first bearing was taken 2.2 nautical miles from the last one. (6 minutes= 1/10th hour X 22 knots = 2.2 miles run.) American navigators learned to apply a bit of "Kentucky windage" to their work in an effort to compensate for this time distortion effect.

-- David G. Brown
 
Mar 22, 2003
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American navigators learned to apply a bit of "Kentucky windage" to their work in an effort to compensate for this time distortion effect.
Sights were taken over a period of about 10 minutes, and the exact time of each site was recorded. Each line of position was adjusted by the speed and direction of ship movement so that they all would corresponded to the same exact time, usually the time of the very last sight taken. Over ten minutes, any error in speed or course angle in these adjustments would be essentially insignificant compared to other errors in measurement. A fix obtained would usually be good to within about a nautical mile barring no errors in the calculations or a systematic error in measurement.
 

Jim Currie

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Sights were taken over a period of about 10 minutes, and the exact time of each site was recorded. Each line of position was adjusted by the speed and direction of ship movement so that they all would corresponded to the same exact time, usually the time of the very last sight taken. Over ten minutes, any error in speed or course angle in these adjustments would be essentially insignificant compared to other errors in measurement. A fix obtained would usually be good to within about a nautical mile barring no errors in the calculations or a systematic error in measurement.
These 6 sights would have been completed by Lightoller in 5 minutes or less A great deal of preparation would have been made by Pitman, long before Lightoller appeared on the bridge after dinner.
Pitman would have calculated the time at or near the meridian of three stars. these would be used to obtain Latitude by Meridian Altitude. He would also select 3 other stars to be worked as Longitudes
Before Lightoller appeared on Deck, Pitman would have prepared a sights sheet. On it, in pairs, would be the names of the celestial bodies to be measured as well as their approximate sextant altitudes of each.
The stars used would already be well known to Lightoller and he would know that they were on the Meridian about 4 minutes earlier each day
When he arrived on the bridge, he would set his sextant to the approximate altitude of the first body. When ready, Pitman would be stationed over the chronometer box with pencil at the ready. Lightoller would measure the first altitude with his sextant and shout "Time" at the appropriate moment. Pitman would note the time on his sheet. Thereafter, Lightoller would reset his chronometer, take the sights in pairs and in order and shout "Time" as each body was brought to the horizon. The whole operation would take less than 5 minutes. More so since the weather was text-book perfect for taking sights.
At the end of it all, Boxhall and Pitman would have calculated between them 3 latitude position lines and 3 longitude position lines.
Since the course was almost westerly, an error in latitude would be instantly obvious.
Boxhall believed that Titanic was making less than 22 knots at that time, therefore, her westerly longitude was changing at the rate of about 1.5 minutes every 3 minutes. This means that there would be a maximum difference of longitude of about 2.5 minutes or 1.68 miles.
It is quite possible that when he was happy with the results...that they crossed checked OK,...Boxhall would have used the middle set of sights. to obtain the fix position of the ship at that time. That would be the position and GMT to be used when calculating subsequent DR positions until the next fix could be obtained.
 

Mike Spooner

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Jan 31, 2018
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Why are you shocked? They were human beings, and they made mistakes, especially when under the pressure of a ship sinking beneath them.
Sam,
They are making mistakes before the thought of a sinking ship. Which I am trying to get the bottom of the matter why? This are very experience officers and the Atlantic is nothing new to them. Now I may trying to bit too precise of a ship position in those days, and it was only approximate position by what margin I don't know?