Distance from the corner to the CQD location


Paul Lee

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Aug 11, 2003
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According to the following websites

http://www.fcc.gov/mb/audio/bickel/distance.html
http://jan.ucc.nau.edu/~cvm/latlongdist.html
http://www.ga.gov.au/nmd/geodesy/datums/vincenty_inverse.jsp

...and others

if you plug in 41 degrees 46 min N, 50 degrees 14 min W
and 42 degrees N, 47 degrees W ("the corner"), the bearing
is 265.54 degrees (true), and a distance of 167.5 statute miles,
or 145.5 nautical miles. The bearing is close to what is quoted (266 T)

For a ship going at 22.5 knots, this equates to 6.47 hours of steaming -
or, for a "turning time" of 5.50pm (which is probably not right, as the turn
was delayed for a while), this means that the time that the ship stopped
was ....... 00:18, which sounds as if some of the 47 minute mooted time change had been
factored into the equation.

Cheers

Paul
--
http://www.paullee.com
 

Paul Lee

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Aug 11, 2003
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Just done a bit more work on this. Assuming Boxhall's numbers (5.50pm turning time, 11.46 stopping time), and at a speed of 22 knots, this leads to a distance of 150.3 statute miles, which would give a CQD position of 41 49 N, 49.55 W

It seems that two ways Boxhall could make such a mistake that would put the ship beyond 50 W, is if he made a mathematical mistake (as in Dave Gittins website), or if he had factored in some of the 45 minute time change into his calculations.

http://www.fcc.gov/mb/audio/bickel/sprong.html

Cheers

Paul
--
http://www.paullee.com
 
Dec 4, 2000
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Much of what follows is based upon a long paper which I have not yet completed that focuses on the various "times" of Titanic. My plan is to publish this paper here with all deliberate haste. It will come with a chronology of about 600 separate events during the sinking.

Paul is getting close to what happened. The setback of the clocks was involved in the creation of the ship's CQD positions. Note that I wrote "positions" because there are two. One is the famous 41 46 N; 50 14 W of Boxhall. As it turns out, this is of lesser interest than the first CQD position of 41 44 N; 50 24 W. It is this first set of coordinates that holds the key to understanding why the wreck lies so far from Boxhall's "final position."

In simple, the "clock" was set back by 24 minutes between the time of rounding "The Corner" and the iceberg accident. Rowe said the corner rounding was at 5:45 p.m. The accident is generally agreed to have occurred at 11:40 p.m. It appears those two times are 5 hours 55 minutes apart, but that is wrong. Due to the 24 minute clock setback, they are 6 hours 19 minutes apart.

Using Boxhall's 22 knots as the ship's speed, at 11:40 p.m. on crew time simple dead reckoning puts Titanic 139 miles west of longitude 47 W, the longitude of "The Corner." On a plotting sheet, this puts the ship on 50 02 W longitude at the time of the accident. Hold that number for a moment.

Due to the clock setback, Titanic had three diffferent "midnights." The first came at "midnight" in April 14th hours. This was midnight for the passengers.

Midnight for the crew came 24 minutes later. The 24 minutes represented the extra minutes worked by the 8-to-12 watch that night. They should have gotten off duty at crew "midnight," which was the same time as when the 12-to-4 watch came on deck.

Titanic's third "midnight" would have come 23 minutes after the crew's midnight. This was when the ship should have crossed its geographic midnight meridian directly opposite from the noon meridian of the sun.

Because of the initial 24 minute setback, the crew was keeping what might be called April 14th-and-a-half time. The next setback of 23 minutes would have placed the crew on April 15th hours. This was the setback of the clocks Pitman said was not done.

The duration from the turning of "The Corner" to true geographic midnight was the 6 hours 15 minutes from 5:45 to midnight plus the total 47 minute setback of the clocks. For practical purposes that's 7 hours of run, which at 22 knots yields 154 miles.

If Titanic had avoided the iceberg and steamed 154 miles from "The Corner," it would have been on longitude 50 24 W at geographic midnight. That is the same as the longitude contained in the ship's initial CQD message. To confirm that this longitude is no fluke, a line drawn at 266.5 true (the ship's course) from longitude 47 W will pass through 50 24 W at latitude 41 44 N.

For all intents and purposes, Titanic's initial CQD coordinates are the predicted location of the ship at geographic midnight, or 0000 hours in April 15th time.

Titanic's accident took place at 11:40 p.m. using crew time. That was 20 minutes before crew midnight which, in turn, was 23 minutes before geographic midnight. That's a total of 43 minutes of time during which the ship could have steamed 15.8 miles. Going backward along the ship's track line that distance arrives at longitude 50 02 West.

Recall that we have been holding 50 02 West as the longitude achieved at 11:40 p.m. crew time based on turning "The Corner" at 5:45 p.m. in April 14th hours. We now have arrived at this same longitude by two different methods. For the record, the 266.5 track crosses this longitude at 41 44 N latitude.

Dead Reckoning of site of impact on the surface of the Atlantic: 41 44 N; 50 02 W.

Captain Smith gave the coordinates of geographic midnight to the wireless officers. Why would he have chosen geographic midnight when he knew the ship had not reached that location? The answer is that Captain Smith seems to have understood that it was better to have ships heading his direction quickly than to wait to calculate a better fix.

Boxhall returned to the bridge just prior to the Captain departing for the wireless office. The fourth officer must have been a bit breathless after two trips into the bow. He had just accomplished the equivalent of climbing and descending a 12 story building. Smith, of course, was trying to digest the horrific truth that Titanic was sinking without enough lifeboats. The conditions of the two men were ripe for a miscommunication.

Smith must have instructed Boxhall to update the CQD coordinates. We do not know what he said, but he must have suggested that the initial numbers were for "midnight." Boxhall probably lost track of time during his double visits to the bow. He looked up, saw it was about midnight..crew midnight..on the clock and went to work.

Based on the initial coordinates, Boxhall simply "backed up" the track by 20 minutes of steaming. That gave him longitude 50 14 W. Then, he added 2 miles of northing to account for the time the ship steamed north after the accident. That produced latitude 41 46 N. He took those coordinates on a scrap of paper to the Marconi office.

Boxhall's coordinates are for where the ship would have been if the accident had occurred at 11:40 p.m. in April 15th hours. Curiously, had the accident not occurred, the crew would have been changing watch at their midnight as the ship crossed 50 14 W.

The dead reckoning position of the accident on the surface can now be used to determine the cumulative effect of currents experienced by Titanic both on the surface and on its way to the bottom. The process is a simple "tails" current vector using the center of the boiler field (41 43.5 N; 56.8 W) as the end of the vector. This produces a cumulative current of about 106 degrees at 0.8 knots.

Here may be another key to the accident. Boxhall testified that he rightly expected the ice to move east and north that night. In fact, the current appears to have been east and south. So, ice that should have been north of the ship's track was either south of it...or "right ahead."

A couple of loose ends-- Boxhall said he used 22 knots as the ship's speed for his calculations. Indeed, the reconstructed plot works properly with that speed even though Rowe's reading of the taffrail log indicated a speed of 22.3 knots. The log was probably more accurate, but this was unknown to the officer who created the projected geographic midnight fix, so is not reflected in that set of coordinates.

The location of geographic midnight was critical to the final clock adjustment. The 23 minute setback planned for the 12-to-4 watch was only an estimate. The actual amount would have been determined by the projected longitude of geographic midnight. The men might have worked 22 or 24 minutes depending upon whether the ship was ahead or behind where it was projected to be at the previous noon. So, it is not surprising that Captain Smith had the predicted geographic midnight coordinates handy when the time came to call for help.

Boxhall said he used Lightoller's 7:30 p.m. star sights in calculating his CQD coordinates. This is true even though he probably "back figured" from the Captain's original midnight numbers. It was necessary to be as accurate as possible in predicting the midnight longitude, so Boxhall would have used Lightoller's fix to improve the prediction made at noon on Sunday.

Boxhall said he thought the time of the accident was 11:46 p.m. Not so according to the two CQD positions.

Finally, the above reconstruction of the ship's track was done on a VP-OS plotting sheet produced by the U.S. Navy. I used ordinary plotting tools which do not yield the umpteen-digit answers that come from calculators. In this respect, my plot is closer to the fuzziness of real world dead reckoning than work done on a computer.

-- David G. Brown
 
A

Alicia Coors

Guest
David, here you said
quote:

...a line drawn at 266.5 true (the ship's course) from longitude 47 W will pass through 50 24 W at latitude 41 44 N.
But here you said
quote:

...the 266.5 track crosses [50 02 W] at 41 44 N latitude.
Is there a typo here, or am I missing something?​
 
Mar 22, 2003
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Geographic midnight is NOT 00:00 15 Apr time. It would have been at approximately 24:23 Apr 14th time, or 24 minutes before 00:00 Apr 15 time. If geographic midnight were at 00:00 15 Apr, then noon would occur at 12:24 instead of 12:00 because of the westward travel of the ship.

Titanic's clocks were set back at "midnight" so that the clocks would read approximately 12:00 at the meridian crossing of the sun at noon the next day. (A slight correction of 1/2 to 1 minutes at most may have been included in the forenoon to make the clocks accurate at noon. See Lightoller's and Pitman's testimonies [US 294-295.]) For the Titanic, the clocks were to go back by 47 minutes that night to make this happen. Assuming they set the wheelhouse clock (used for watch keeping purposes) back 23 minutes in the First Watch (8-12) so that 8 bells is rung when it struck 12, then they would have to set the wheelhouse clock back another 24 minutes when the Middle Watch (12-8) came on, and at that time change all the other ship's clocks back 47 minutes so that all clocks would read the same time. (This was done using the master clocks in the chart room.) This scheduled setback was NOT done that night because of obvious reasons as Boxhall explained.

So even though I agree with you, Dave, that the wheelhouse clock may have been set back in the First Watch so that 8 bells came when it struck 12, I do not believe Boxhall would have used that clock for navigation purposes. He had the chronometers and the ship's master clock to work things out.
 
A

Alicia Coors

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This is just a guess, but since longitude is calculated as the hour angle from Greenwich, it doesn't make sense that Boxhall would have used anything but the GMT clock to do his calculation. The only variance I can think of would be if the time of the evening sight was logged in ship's time. Anybody have an educated guess whether this was the case?
 
Mar 22, 2003
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One more thing about locations and courses. Rowe did not say they turned The Corner at 5:45 PM. He said they altered their course at 5:45 PM. That is NOT the same thing. Also, a rhumb line heading taken from The Corner 42*N 47*W to 41* 44'N 50* 24'W is 153 nautical miles at 264 deg true, not 266.5. The Titanic was following a rhumb line heading of 266 true from the a/c point, not The Corner. (Even while following the great circle route from the Fastnet to The Corner, she would be following a series of rhumb lines.)

The second point I would would like to make is that Boxhall was quite specific about how he calculated his CQD popsition. He said he used the 7:30 PM celestial fix and ran a course of 266 deg true at a speed of 22 knots to the collision point which he assumed to be at 11:46 PM. No mention of factoring in any northern movement or using a midnight DR and back navigating from that.

What we do know about locations and times from which one can work with is the specific location of the wreck site, the calculated CQD position of Boxhall, an initial CQD position assumed to be for geographic midnight, the total clock setback time of 47 minutes for that night, the planned a/c time of 5:50 PM (14 Apr time), and a 7:30 PM time (on 14 Apr) for a celestial fix the coordinates of which are unknown to us and to be derived.

Dave, as you know, I have been struggling with all this for quite some time, but I have come out with a solution that fits all the known facts quite well. Although I am not ready to post the details of this work, others including yourself have seen parts of it. It does hang on one specific assumption that Boxhall made an error, not in time, but in converting miles to longitude by reading off the wrong column in a transverse table, something suggested by Dave Gittins some time ago http://users.senet.com.au/~gittins/sospos.html. The other assumption, but less critical and based on circumstantial evidence, is that the speed of the Titanic may have been increased at the start of the 8-12 watch that evening to about 23 knots over water. When these two are factored in, the so called "initial" CQD position falls on the the geographic midnight location of 41*44'N 50*24'W for 24:23 14 Apr time, the calculated collision point comes very close to the wreck site at 41*43.2'N 49*58.1'W, the 7:30 PM celestial fix is at 41*52.5N 47*53.5'W, the a/c point is at 41*56.3'N 47*04.8'W, noon 14 Apr location of 43*0.5'N 44*35.1'W, and a current with a drift of 0.78 knots and set of 147 deg true, which also was derived by allowing for ship movement around the berg and some movement north (1.8 miles) afterward. These results are subject to review and revision, as I said. The preliminary plot that I got of the ship's track over ground is shown below. The corrected CDQ position shown is what it should have been if no error were made.

86240.gif
 
Mar 22, 2003
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Alicia: I believe all logbook entries were required to be in GMT. The celestial fix on the chart would probably have included the time in GMT and maybe local ship's time marked as well. IMO, it would be unlikely for Boxhall to use the wrong clock time in calculating a DR. His work would most likely have been done in the chartroom which had the master clocks keeping ship's time as well as the chronometers there. If there were a clock setback it would be in the wheelhouse clock used for watchkeeping purposes, so when it struck 12, 8 bells would be rung and all clocks setback to correspond to Apr 15 hours. This would be approximately at the geographic midnight location, assuming the ship continued to move on its course.

BTW, there apparently were two clocks in the wheelhouse. My guess is that one was on ship's time while the other was used by the standby QM to ring ship's bells. It would be the latter clock that would undergo two setbacks per night to split the total setback equally between the two watches.

944. Were there two clocks in the wheelhouse? - Yes.
945. Do you remember the vessel striking? - Yes.
946. Did you notice the time when she struck? - Yes.
947. What was it? - Twenty minutes to twelve.
...
1017. How long did you remain at the wheel? - Until 23 minutes past 12.
1018. And who relieved you? - Quartermaster Perkis.

And from the US hearings:
Mr. HICHENS. ... I stayed to the wheel, then, sir, until 23 minutes past 12. I do not know whether they put the clock back or not. The clock was to go back that night 47 minutes, 23 minutes in one watch and 24 in the other.
Senator SMITH. Had the clock been set back up to the time you left the wheel?
Mr. HICHENS. I do not know, sir. I did not notice it.

Collision at 11:40 PM 14 Apr ship's time is consistent with a travel time 11.67 hours from local apparent noon to the vicinity of wreck site. The covered distance over ground is about 257 nautical miles/11.67 hours = 22 knots. If the collision would have occurred 24 minutes later (at 11:40 wheelhouse clock time that was set back 24 minutes from 14 Apr time), then that would put the ship about 9 miles further west of the wreck site. The mileage from noon to near the wreck site is also consistent with Rowes reading of the taffrail log which was 260 miles through the water in 11.67 hours, or 22.3 knots over water. They were bucking a south-easterly current.

As an aside, the equation of time is not a factor in determining longitude or local apparent noon for these dates since it just happens to equal 0 on Apr 15th.
 
Dec 4, 2000
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The time of "midnight" is not a single instance for Titanic. It was three events. The geographic meridian of midnight would have been approximately the initial 50 24 W of the initial CQD transmission.

The word "approximately" is quite deliberately chosen. The dead reckoning techniques of 1912 and even the accuracy of star sights made navigation more art than science.

Working backwards, and including the clock changes, the reciprocal of 266.5 T (which is 086.5 T) crosses 47 W longitude at the time when Rowe said they altered course. This was effectively "turning The Corner" although it was about 8 miles south of the proper 42 N latitude.

In reading Sam's post I realize that in searching for a term for true midnight I was a bit wrong in using "geographic." I wanted a word that would convey that this was a midnight based on the ship's location and not upon the internal clocks. Perhaps I should have chosen "physical" or some such word.

However, by whatever word you want to call it, 50 24 W is where Titanic would have been (approximately) at the moment when April 15th hours began and all of the clocks were "correct" for noon on the 15th as Lightoller described.

The dead reckoning is simple and straightforward if you take into account the time change. And, most important, it puts the three known locations into logical context: 1.) initial CQD coordinates; 2.) Boxhall's CQD coordinates; and 3.) the wreck today.

Hichens was released from the wheelhouse at 24 minutes past midnight in April 14th hours. He was off by 1 minute in his testimony. Perkis, his relief, did not take over in the wheelhouse. Both men went to preparing lifeboats. Keep in mind that no matter what Hichens said, the rest of the crew (including Perkis) considered that the midnight change of watch was due 20 minutes after the accident.

Sam and I have discussed when they would have set the clocks back during the watch. He thinks they did it at the end of the watch. That is, 8 bells rang and the crew did 24 or 23 minutes extra duty before change of watch. Not so per the testimony. Remember, 7 bells had just struck within 10 minutes of the accident (see Scarrott's testimony). So, 11:30 was 7 bells. And, the testimony of men about to go on duty is that they were awakening to get dressed. That would have happened no later than 11:45 p.m. And, everyone agreed that the change of watch was at midnight which was 8 bells marking the watch change. From the testimony, it is obvious that the 24 minute setback of the clocks took place sometime during the 8-to-12 watch. My assumption is that it happened at the start where it would have been most convenient for everyone.

One final note about using ship's time for navigation. That's obviously one source of error that night. Had everything been done in GMT, there would have been no reason for Boxhall's CQD coordinates to be "off." However, there was one navigational evolution which absolutely required calculating "midnight," and that was the resetting of the clocks. Perhaps every other bit of navigation was done in GMT. There is no evidence either way. But, finding "midnight" had to be done in local ship's time because it was for the purpose of correcting that time.

-- David G. Brown
 
Jan 11, 2006
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David Brown wrote:
quote:

...the first CQD position of 41 44 N; 50 24 W. It is this first set of coordinates that holds the key to understanding why the wreck lies so far from Boxhall's "final position."
Leslie Reade in "The Ship That Stood Still" page 116, wrote:
quote:

In the talk given by Commander Boxhall in 1959 about the Titanic, he explained that Captain Smith told him the first position sent out was “the 8 p.m. dead reckoning one, and asked how it compared with the 7:30 p.m. star position, and was told that this showed the ship to be ahead of the DR position. Thereupon he gave orders that this should be given to the wireless operator for transmission. And that, explained Commander Boxhall, was why the Carpathia received two position.”￾ Fifty-two years later, when I asked him much the same question, I received much the same answer.
[Note: British report shows Carpathia receive one, only, CQD position]

Geoffrey Marcus, in "The Maiden Voyage" Page 133
wrote,
quote:

The Captain then told him [Boxhall] that the position that had been sent out in the general distress cal was the 8 p.m. dead reckoning one and enquired how it compared with the 7.30 p.m. stellar position. Boxhall went at once to the chart room and worked it out. The present position, calculated from the stellar observation at dusk, was found to be lat.41 46'N.,long 50 14'W which showed the ship to be about 20 miles ahead of the D. R. position. The Captain ordered him to take it to the wireless office. Boxhall obeyed.
 
Mar 22, 2003
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The initial CQD that was sent out, 41*44'N 50*24'W, was picked up by Cape Race and also the Mt Temple. This is about 7.5 miles west of Boxhall's CQD position. The explanation given by Boxhall just not appear to make any sense. What turns out to be close to 20 miles is the difference from this initial CQD position and the wreck site.
 
Jan 11, 2006
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quote:

The explanation given by Boxhall just not appear to make any sense. What turns out to be close to 20 miles is the difference from this initial CQD position and the wreck site.
The armchair interpretation by Leslie Reade and Geoffrey Marus of what Boxhall is alledged to have said does not make sense.

quote:

It does hang on one specific assumption that Boxhall made an error not in time, but in converting miles to longitude by reading off the wrong column in a transverse table...The other assumption, but less critical and based on circumstantial evidence, is that the speed of the Titanic may have been increased at the start of the 8-12 watch that evening to about 23 knots over water.
Your asumptions, along with discounting the evidence of 3/O Pitman who said the distance from Noon 14th to the corner 42N/47W was 110.5 nm, and the evidence of QM Rowe, who said he steered the course of S85°W by the steering compass (S62°W true)from noon to a/c 5:45 p.m. do not make nautical sense and in effect 'fudge' the solution.​
 
Dec 4, 2000
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What makes sense to me is the reverse dead reckoning from the initial CQD position. Using it as the ship's true "midnight" when April 14 would have become April 15, and 22 knots of speed (per Boxhall), the three key locations come into correct juxtaposition. These are the two CQD positions, and the course change.

Boxhall retraced 20 minutes (11:40 p.m. to "midnight") of steaming and moved the position 2 miles north. This accounted for what he assumed was the time not steamed between the accident and "midnight;" and for the northing accomplished after the accident. It was not a fix, but his best effort at a "most probable position" based upon navigation work he had been doing from 10 p.m. onward that night.

The third critical element is the location where the ship changed from great circle to rhumb line navigation. This was "The Corner" to the crew. It should have taken place on 42 N; 46 W. but Captain Smith supposedly delayed making the course change. Using 22 knots, and accounting for the 24 minute clock change, a backwards DR track starting at the initial CQD coordinates crosses 46 W at 5:45 p.m. precisely as it should if Rowe's testimony is correct.

Now, back to the wreck. It cannot lie on the bottom directly beneath the location on the surface where the ship lay stopped as it sank. The ocean is always moving due to currents. In that location, two would have affected the sinking hull: the Labrador and the Gulf Stream.

Backing up 43 minutes (the un-done 23 minute setback plus the 20 minutes from 11:40 to midnight) of steaming puts the ship at 41 44 N; 50 03 W. That would be the DR of the accident based upon this reconstructed plot. And, using that spot and the wreckage on the bottom, a current of 106 at 0.8 knots is obtained using the "tails" current vector method.

Boxhall said he used the ship's course and speed, and Lightoller's star sights to compute his "final" CQD coordinates. This is true even if he simply backed up the projected midnight lat/lon of the initial distress messages. The midnight position required careful use of dead reckoning updated from Lightoller's fix. And, Boxhall said he did the number crunching for the information plotted by Captain Smith prior to the accident. So, Boxhall had done the work and had every reason to trust the Captain's midnight position.

Significantly, the computation of true midnight was the only one which required the use of ship's time in place of GMT. This difference may have been the real basis for the misunderstaning between Smith and Boxhall.

One final observation--Boxhall's CQD coordinates were certainly close enough to bring all of the ships that responded to within visual range of Boxhall's green rockets. Had there been typical stormy and/or foggy weather the entire passage, a 13 to 15 mile "error" in the ship's DR would not have been considered unusual. So, the masters of ship's coming to the lifeboats would have known to keep lookout over a wide portion of the horizon. It is a temprocentric mistake (born of GPS and other electronic navigation systems) made by modern investigators to think that potential rescuers were homing in on a specific geographic spot. In 1912 masters would have assumed the coordinates were only an approximation of reality and that good seamanship would be required in the end to find the lifeboats. Talk to anyone involved in search and rescue today and you will find that not much has really changed.

-- David G. Brown
 
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quote:

What makes sense to me is the reverse dead reckoning from the initial CQD position. Using it as the ship's true "midnight" when April 14 would have become April 15, and 22 knots of speed (per Boxhall), the three key locations come into correct juxtaposition. These are the two CQD positions, and the course change.
That, to me, makes absolutely no nautical sense. Boxhall was a professional navigator who navigated from the 7:30 P.M. six star observation. There is no logical reason why he would substitue that observed position for a reverse dead reckoning from a DR CQD position.​
 
Mar 22, 2003
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Capt Collins: Just a couple of points of clarification.

First, I agree with you that it is the explanations given by and Reade and Marcus of what Boxhall had told them that does not make sense. I stand corrected.

Second, in the preliminary work that I reported on I did use the course given by QM Rowe that was steered from noon to the a/c point of 242[sup]0[/sup] true. And from the a/c point the course steered was 266[sup]0[/sup] true. What I had shown was the track over ground that I got which would include the affect of current. The assumption I used, and I know it may not be exactly right to do so, is that the ship was affected by the same current set and drift from noon through the accident and up until the time it sank. What I was also trying to do is see what the approximate noon position would be if we worked the problem forward as well as backward. We know what the daily runs were from the time the vessel left Daunt Rock at 14:20 GMT on Apr 11. These runs were reported as 484+519+546=1549 miles. If we follow the intended track from Daunt Rock around Kinsale to Fastnet light, then along the great circle route with this mileage, we can obtain the approximate position of the ship at noon for Apr 12, 13, and 14. In my work up, I assumed the ship was following short rhumb lines along the great circle route changing course about every 5 deg of longitude. The last rhumb line being from 40W on the great circle route to the corner at 42N 47W. What I got working the solution that way was a noon 14 Apr location of 43[sup]0[/sup] 4.9'N 44[sup]0[/sup] 33'W.

Working it the other way, from what I call the corrected 7:30 fix backward on the reciprocal of 266 true to the a/c point at 5:50 PM, then on the reciprocal of 242 true to noon, and including the effect of the current, I came to 43[sup]0[/sup] 0.5'N 44[sup]0[/sup] 35.1'W. And as can see from the diagram I posted, the two are within a few miles of each other, coming from different directions. By the way, if you take a direct path from 43[sup]0[/sup] 0.5'N 44[sup]0[/sup] 35.1'W to the corner, you will see that it happens to be on a rhumb line of 240.6[sup]0[/sup], which is close to what Lowe said was the course from noon to the corner of 240.56[sup]0[/sup].

What I did not do is take 110.5 miles from noon to the corner as a given. I know that you derived that distance by multiplying 22.1 knots by 5 hours, and the 5 hours came from Pitman's statement at the BOT hearings that he expected the ship to be up to the corner at 5 PM. At the American hearings he was asked about the corner by Senator Fletcher to which he replied:
"Mr. PITMAN. Yes, we were supposed to be at the corner at 5.50."
He also said the ship was making 75 revolutions and going at 21.5 knots based on the revolutions and the log. And Lowe thought the ship was going at 20.95 knots. Yet QM Rowe's log reading 260 miles implied a speed of 22.3 knots through the water from noon to the accident, and Hichens log reading between 8 and 10 PM of 45 miles indicated 22.5 knots. So we have a bunch of different speeds to work with. Which one do you like to use?
 
Mar 22, 2003
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On the matter of how Boxhall calculated his CQD position, I have to agree with Capt Collins. Why work it backward? Boxhall was quite specific as to how he computed his CQD location. He had the 7:30 PM fix; he had the course of 266 true; he used an estimated speed of 22 knots; and he used an estimated time of collision of 11:46 PM. Those are the parameters that he said he used to get his CQD position. What I would question is how the initial CQD position was calculated. Was it a midnight location marked on the chart based on the 7:30 fix that was put down at about 10 PM, or was it based off of the 8:00 PM DR worked up by Lowe?
 
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Samuel:
quote:

What I would question is how the initial CQD position was calculated. Was it a midnight location marked on the chart based on the 7:30 fix that was put down at about 10 PM, or was it based off of the 8:00 PM DR worked up by Lowe?
What I question is the so called initial CQD position (41°44'N 50°24'W} purportedly sent by Capatin Smith. There is no evidence to support this notion.

quote:

We know what the daily runs were from the time the vessel left Daunt Rock at 14:20 GMT on Apr 11. These runs were reported as 484+519+546=1549 miles.
This is not correct. 14:20 is not GMT. There are errors in the Memorandum of Mr. Pitman.

The first day's run of 484 states a speed of 20.14 knts -this is incorrect as it gives 21.6 knts.

The second day's run run states 519 nm gives a speed of 21 knts, which indicates a speed reduction, instead of increase, from first day's run. Although, this Memorandum is credited to Pitman I have doubts it was prepared by 3/O Pitman.

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If we follow the intended track from Daunt Rock around Kinsale to Fastnet light, then along the great circle route with this mileage, we can obtain the approximate position of the ship at noon for Apr 12, 13, and 14. In my work up, I assumed the ship was following short rhumb lines along the great circle route changing course about every 5 deg of longitude. The last rhumb line being from 40W on the great circle route to the corner at 42N 47W. What I got working the solution that way was a noon 14 Apr location of 430 4.9'N 440 33'W.
Titanic did not follow the great circle route of changing course about every 5 deg (or 10 deg) of longitude. At 7pm GMT, April 12th, her position of 49° 45'N, 23° 38'W, was outside both GC routes.

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QM Rowe's log reading 260 miles implied a speed of 22.3 knots through the water from noon to the accident, and Hichens log reading between 8 and 10 PM of 45 miles indicated 22.5 knots. So we have a bunch of different speeds to work with. Which one do you like to use?
Factoring in the effect of the Gulf Stream both make the speed over ground to be approx 22 Knots

Regards,
Collins​
 
Dec 4, 2000
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Boxhall's testimony of how he calculated his "final" CQD position is true in my version of events. He had helped Captain Smith from 10 p.m. onward with navigation. Much of that work involved the plotting of ice, but it was absolutely necessary for them to have worked out the ship's true midnight position as well. To do that, Boxhall and/or Smith would have used the ship's course, speed, and 7:30 p.m. fix. So, the predicted true midnight would have been done exactly as Boxhall said. By "backing out" 20 minutes of steaming, Boxhall simply refined the midnight DR position. And, he was absolutely correct in saying it was based upon 22 knots at 266 using the 7:30 p.m. fix.

The only statement in Boxhall's testimonies (U.S. and British) that can be proven incorrect is his claim to have shown his corrected CQD position to the captain. At the time, Smith was being seen by several passengers making his way down the grand stairway and lower. The senior officer on the bridge at that moment was most likely Chief Officer Wilde who was "out of the loop" when it came to the navigation. Wilde had been off duty for almost 6 hours at the time of the accident and would not necessarily have recognized any problems involving Boxhall's coordinates.

All of the navigational information from Daunt Rock is curious, but is really not germane to this discussion. We are talking about at most 43 minutes of time out of days of steaming or a maximum of 15.7 miles. Every number calculated for the ship's distance made good has at least that much margin for error. Particularly when you consider that we have very little accurate data, and that was acquired using 1912 celestial navigation--not modern electronic devices.

The evidence lies in the juxtaposition of the two CQD positions, the location of the wreck, and the time when Titanic would have crossed 47 W longitude. My theory (and it is a theory) puts all of these elements into context. It does so within the confines of 1912 navigation and it meets the test of the sworn testimonies.

The mis-read table theory (which I previously favored) does not explain the timing of the course change from Great Circle to rhumb line. Most critical, it cannot explain how the initial CQD position was obtained, nor why the intial position is rather precisely 20 mintues of steaming west of Boxhall's longitude and 2 miles south--which matches the known facts of an accident 20 minutes before "midnight" and the ship steaming at "half speed" for 10 to 12 minutes after the accident.

For there to have been a mis-reading of the tables, the facts represented by the two CQD positions require that two such errors were made, not one. And, it requires that Captain Smith had foreknowledge of Boxhalls 2 miles of northing. If so, why didn't he just add that before giving his initial coordinates to the Marconi office?

Any DR plot from the 7:30 p.m. celestial sights must take into account the 24 minute setback of the clocks. This is mandated by Lightoller's testimony about the way the clocks were handled on Titanic (he spoke of no other ship, just Titanic). And, it is mandated by the fact that Lightoller confirmed the times of the accident and sinking were given in local apprent time for 50 W longitude and not in either ship's time for Noon Sunday or Noon Monday. If the ship was keeping time halfway between noons, perforce the clock by which the accident was referenced must have been retarded by the 24 minutes which the crew expected to serve extra during the 8-to-12 watch. So, the duration 7:30 to 11:40 is not 4:10, but 4:34.

And, the duration from the turning of "The Corner" at 5:45 p.m. to true Midnight is not 6:15. Rather it is 6:15 plus the 47 minute retarding of the clocks, for a total of 7:02.

Plug these durations into the time/speed/distance formula using Boxhall's stated 22 knots and the DR kept on Titanic's bridge comes clear.

41 44 N; 50 24 W True midnight

41 46 N; 50 14 W True midnight - 20 min + northing

41 44 N; 50 03 W Most probable position accident

41 35.5 N; 49 56.8 W boiler field on bottom

41 50 N; 47 55 W Lightoller's celestial fix

41 53 N; 47 00 W Course change GC to rhumb line

-- David G. Brown
 
Jan 11, 2006
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Boxhall's testimony of how he calculated his "final" CQD position is true in my version of events. He had helped Captain Smith from 10 p.m. onward with navigation. Much of that work involved the plotting of ice, but it was absolutely necessary for them to have worked out the ship's true midnight position as well. To do that, Boxhall and/or Smith would have used the ship's course, speed, and 7:30 p.m. fix. So, the predicted true midnight would have been done exactly as Boxhall said. By "backing out" 20 minutes of steaming, Boxhall simply refined the midnight DR position.
There is no evidence or nautical logic to support that conclusion What is meant by "true midnight"?

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The evidence lies in the juxtaposition of the two CQD positions,
There is no evidence or nautical logic to support the notion of two CQD positions

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The mis-read table theory (which I previously favored) does not explain the timing of the course change from Great Circle to rhumb line.
What is meant by "the course change from Great Circle to rhumb line."?

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Most critical, it cannot explain how the initial CQD position was obtained,
Again there is no evidence or logic to support two CQD postions.


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...nor why the intial position is rather precisely 20 mintues of steaming west of Boxhall's longitude and 2 miles south--which matches the known facts of an accident 20 minutes before "midnight" and the ship steaming at "half speed" for 10 to 12 minutes after the accident.
There is no evidence or logic for the ship steaming NORTH after the accident. Quite the contrary, it is absurd to believe that Smith steamed his ice-damaged, sinking by the head, ship any distance in any direction. True there is Olliver's testimnoy that Captain Smith rang "Half Ahead", but basic seamanship is, that manoeuvre was to killed the stern way, gathered from backing full astern.

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Any DR plot from the 7:30 p.m. celestial sights must take into account the 24 minute setback of the clocks.
Which would make midnight position 41° 45'N, 50° 36'W

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This is mandated by Lightoller's testimony about the way the clocks were handled on Titanic (he spoke of no other ship, just Titanic). And, it is mandated by the fact that Lightoller confirmed the times of the accident and sinking were given in local apprent time for 50 W longitude
From what evidence is that conclusion derived?

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If the ship was keeping time halfway between noons, perforce the clock by which the accident was referenced must have been retarded by the 24 minutes which the crew expected to serve extra during the 8-to-12 watch. So, the duration 7:30 to 11:40 is not 4:10, but 4:34
But there is no evidence to support that contention. Quite the contrary, all evidence is that the clocks were not retarded.

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And, the duration from the turning of "The Corner" at 5:45 p.m...
The corner 42N/47W was not turned at 5.45 p.m. The course was altered at 5.45, S 72°W true- 16.4 miles from the corner.​
 

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