Navigational Refutation of Titanic's CQD Position


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Alicia Coors

Guest
In a monograph published on the E-T site, Capt. L.M. Collins provides a meticulous cross-check of Fourth Officer Boxhall's arithmetic in computing Titanic's position when the ship began to sink. He demonstrates with egregious precision how a position of 41°46'N 50°14'W is calculated by dead-reckoning from her last position determined by stellar observation, 4h19m prior to the collision.

Dave Gittins suggests that Boxhall misread his Traverse Tables while crunching the numbers, and therefore the CQD position is suspect. I think there is a far simpler explanation.

The word "current" is not found in Duke's article at all; Dave mentions it exactly once (in the context of the 1990-92 computation, not his own).

A reasonable person would dispute the contention that Titanic drifted ~13 nm. from her presumed position at the moment of collision to the wreck site. If the distance/time equation is solved for ~13/~2, the current would have to be around 6 knots(!) This is unlikely the case. An explanation for the 13 miles must lie elsewhere.

Since Boxhall's computation apparently works if the current is ignored, I believe that the drift should be applied over the total time between the evening shoot and the sinking (an interval of 6h39m) giving an average velocity of a little less than 2kt.

Applied to the time between the celestial shoot and the collision, a drift of 8.5 nm at this rate would have occurred; from collision to wreck site, the remaining distance of 4.5nm would be traversed.

Titanic encountered her fate at 41°44'N 50°W.
 

Paul Visser

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Sep 19, 2007
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Alecia,

>>Dave Gittins suggests that Boxhall misread his Traverse Tables while crunching the numbers, and therefore the CQD position is suspect. I think there is a far simpler explanation.<<

Lets not forget that Captain Rostron, Master of the Carpathia, found and rescued the survivors on the position given by the Titanic. There is no doubt that Officer Boxhall's dead reconing was absolutely correct give or take a few miles taking drift into consideration and the distance Titanic went ahead after she struck the iceberg.

Paul
 
A

Alicia Coors

Guest
Rostron ran in the direction he thought Titanic was from him and happened to find Boxhall (and about an hour sooner than he expected to!). On a course of 308° true to the CQD coordinates, Carpathia would have passed within 5 miles of the wreck site.

Dave Gittins says that when Carpathia picked him up, "Boxhall was probably no more than a mile or so south of the wreck, having drifted on the southerly* current..."

That puts him 14 miles from the CQD position.

* Actually, the current seems to have been a little south of due east.
 
Aug 10, 2002
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Hello All:
A check of the North Atlantic Pilot Chart for the Month of April in the location of the accident shows the current as E x N at 0.5 kts. In the 2.6 hours generally used as the elapsed time from collision to sinking that would indicate an E'ly drift of 1.3 miles.
Regards,
Charlie Weeks
 
Jan 11, 2006
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In the 2.6 hours generally used as the elapsed time from collision to sinking that would indicate an E'ly drift of 1.3 miles.

Capt. Weeks,

That would be, of course, surface currents. Do you have any info on underwater currents? My info, from a hydrographer friend, is Gulf Stream (North Atlantic current) in conjunction with Labrador current is up to max 6 knots ENE

Regards,
Collins
 
A

Alicia Coors

Guest
Something doesn't compute.

If Boxhall's navigation was accurate (but failed to account for a .5 kt current affecting the ship since the sundown observation), then the wreck site should be 3.33 miles from the CQD position.

Could Boxhall really have been as much as 10 miles off in computing something as important as the position to be broadcast in a distress call?

I would have to question the validity of the NAPC.
 
Dec 2, 2000
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>>Could Boxhall really have been as much as 10 miles off in computing something as important as the position to be broadcast in a distress call?<<

Yes. He did the best with the information he had, but unfortunately, his calculations were only as good as the information he had. The GIGO factor applies. However, in fairness to Joe Boxhall, I think David Brown said it best at a gathering I attended when he pointed out that all that's been "proven" is that they didn't have GPS.
wink.gif


In addition to This Link which you provided, you may find it useful to read through the Next Part of Dave Gittins site if you haven't done so already. The mistake in position was recognized even then by both the Mount Temple and the Californian, but nobody wanted to listen.
 
A

Alicia Coors

Guest
Follow me through here:

1. It is safe to assume that Titanic's position was known with a high degree of accuracy when the stellar observation was made at 22:21 GMT (civil twilight). As a cross-check on this computation, Lowe's testimony confirms that the evening position was consistent with the ship's course and speed since noon.

2. Boxhall could quickly dead-reckon Titanic's position as 41°46'N 50°14'W following the collision by drawing a line 95 nm long (4h19m @ 22 kts) on a course of 266° true from the twilight position. Boxhall would use his GMT clock to determine the elapsed time, so the ambiguity of ship's time wouldn't have affected accuracy.

3. But the CQD position was not corrected for a west-to-east current of about 2 kts (so it was, in fact, incorrect); the actual location of the collision was 41°44'N 50°W - 8 miles east of the computed position. This is the error noted by Mount Temple.

4. By the time the fantail disappeared, the current had carried the ship another 4 miles, to the place the wreck lies today.

5. Carpathia's fortuitous encounter with Lifeboat 2 may have resulted from Rostron starting from east of where he thought he was, but it may also have been because the current carried him eastward as he neared the sinking site.
 
Aug 10, 2002
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Alicia:
Pilot Charts were started by Matthew F. Maury in the mid 19th century, by extracting information from ship's logs. Today they are produced by National Imagery and Mapping Agency, over the years I and many other mariners have found the information on them to be very accurate. As Capt. Dave Brown has said in others posts, Boxhall's method was correct by his answer was wrong. Fortunately Carpathia's trackline to the CQD position brought them on to the lifeboats, and Boxhall ignited a flare to give them timely warning of their presence. How Boxhall got the wrong answer has been the topic of much discussion. Unfortunately the evening star fix position is unavailable to us. Only comments about it.
Duke, you are correct the Pilot Charts only show surface currents, but Titanic max. draft of 34' would have been effected by them not deeper currents.
Sam, my Pilot Chart shows the same currents at both locations. The Labrador Current is south bound till it gets in this area then it starts to turn and run E'ly. Other sources claim the Labrador Current dives under the Gulf Stream.
Regards,
Charlie Weeks
 
Jan 11, 2006
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Boxhall's method was correct by his answer was wrong.

Charlie:

What logical reason can be given for Boxhall's answer to be wrong on a run of 4 hours 10 minutes?

Duke, you are correct the Pilot Charts only show surface currents, but Titanic max. draft of 34' would have been effected by them not deeper currents

I am quite aware of that, but don't you think the underwater currents would have had an effect after Titanic submerged?

Regards,
Duke
 
Dec 6, 2000
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I find it very hard to believe that underwater currents would have much affect on a boiler, heavy and dense, after the boiler fell out of the broken ship. I believe the boilers pretty much fell straight down, and they landed pretty much below where the ship disappeared on the surface.


Other parts of the broken ship could be affected by an underwater current, depending on their shape and weight.
 
Aug 10, 2002
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Duke:
I don't know why Boxhall's answer was wrong, but it certainly was, by 13+ miles. There are many possible reasons, the current being part of one. I know Dave Brown has been wrestling with this question for years. And no I don't think the underwater currents would have had much effect on her as she sank. I'll go with Bill Wormstedt on that one, boilers are probably directly under the spot where she broke open. Also I piece I saw on Discovery Channel , showed them sinking a model hull ( simulated fwd half of Titanic)in a pool and it didn't drift very far afield, so I doubt the Titanic did.
Regards,
Charlie
 

Paul Lee

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Aug 11, 2003
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Hi Charles,
Don't forget the pool didn;t simulate the true distance to the bottom.... but in the meantime, I agree with Dave Gittins. Don't forget that Boxhall was under pressure to produce "a" position. The fact that he went back and recomputed it may be symptomatic of this.

Best wishes

Paul

 
Jan 11, 2006
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I don't know why Boxhall's answer was wrong, but it certainly was, by 13+ miles.

I don't think the underwater currents would have had much effect on her as she sank.

Charlie;

Although, I disagree, I thank you for your opinion.

Regards,
Duke
 
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Alicia Coors

Guest
As I have pointed out before, reducing the scale by 1000:1 gives you a .892' (11") ship dropping 12½ feet. The pieces land within a foot of directly below the point of release. If a current had any effect, it would have had to take place within six minutes or so.

Boxhall's recalculation presents an enigma: how would two computations result in two answers so close to each other, yet both so far from the actual value?

Unless neither accounted for drift since the celestial sight. Which would put him about 8 miles away from his true position. Which is where Mt. Temple figured he was.
 
Mar 22, 2003
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All parts of the ship would drift with any underwater currents on the way to the bottom, no matter how much they weighed. But those that were the highest densities (like boilers) would fall to the bottom the fastest. If they took about 6 minutes to sink, which is a good estimate (see Ballard's book), then any underwater current would have a trivial affect on the final resting place. Bottom line, the Titanic disappeared over its final resting place.

That said, I think Alicia is on the right track with this one. One question I do have, was the last set of star sights taken at civil twilight, or nautical twilight? Not really knowing the time (GMT) of the sights, or the the fix that was calculated, it would be difficult to work the problem backwards.
 
Aug 10, 2002
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I would say Civil Twilight, my nav. software says civil twilight was at 1928 for 4/14/12 Lat. 41-30N, Lnog. 50-10W. Bowditch say Nautical twilight the horizon is too dark. I don't envy him using the type sextant he would have had. I have a U.S. Navy sextant Mark I, from the First World War, my reading glasses have more magnification.
I also would agree with Alicia, it would be about like dropping a rock in a pool.
Regards,
Charlie
 

Dave Gittins

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Apr 11, 2001
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Boxhall says the celestial position was worked out for 7-30 ATS, which is in the ballpark found by Captain Weeks. This is an oversimplification of what really would have been done. They took six sights, three for latitude and three for longitude. That would have taken about ten minutes. Lightoller was taking the sights and Pitman was assisting. Pitman would have taken the time of each sight by using a deck watch to relate the time to the chronometers. I'll bet Pitman also read the sextant inside in the chart room. As Captain Weeks says, sextants of the period were hard to read and needed good eyesight and plenty of light. Boxhall worked the sight reductions, using very long and tedious methods that haven't been taught for years. Because Titanic was so fast, he would have adjusted each observation to allow for the distance run between the sights. Unfortunately, there is no way of working out the position thus obtained. Having done all this work, plus compass checks, Boxhall must have been very weary when he came to work the SOS position. He'd been working four hour watches for days. He may also have been unwell, which he certainly was on arrival in New York. I'm not surprised that he made a mistake, whether with the Traverse Table, trigonometry or any other means.
 

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