Keeping Track of a Maiden Voyage

[L. Marmaduke Collins]

Referencing ET article Keeping track of a Maiden voyage.

Apart from changing the evidence of 5th Officer Lowe and ignoring the evidence of 3rd Officer Pitman to Br Inquiry, what is the logic for adding 126 miles to the route distance of 1492.8 miles (from off Fasnet to Noon 14th Memorandum of Mr. Pitman) making a total route distance of 1618.8 nm ?

noon position of 43° 02’ N, 44° 31’ W. This position is a total distance run of 1549 miles from Daunt’s Rock over the course that was traveled.

+126 = 1675 - 56.2 =1618.8

The GC distance from off Fasnet to the Corner 42/47 = 1618 (1617.9) nm
The 5° longitude rhumb line route distance = 1623 (1623.1) nm
The 10° longitude rhumb line route distance = 1624 (1624.3) nn

Are you suggesting that Titanic sailed a true GC track from off Fastnet to the Corner?

As Titanic did not follow either of the above routes. Her first course alteration was made to the north, at 7 PM GMT 12th, at 49° 45 'N, 23° 38' W. Therefore, her total route distance sailed from off Fasnet to the Corner was greater than 1624 (1624.3) nm

[Moderator's Note: This message, originally posted as a new thread under a different topic, has been moved to this more appropriate location. MAB]

 

[Bill West]

Good Morning, Captain
Those 1623/24 mile rhumb line routes are for a flattened sphere earth. Footnote 18 mentioned that Sam used round sphere calculations, they would be consistent with 1912 practice and testimony.

Bill

 

[L. Marmaduke Collins]

For the work I did on the Titanic, I got 1675.5 miles from Daunt's Rock to the corner, totally consistent with that Olympic data.

1675.5 miles is not necessarily applicable to Titanic. It incorporates 126 miles, a figure arbitrarily derived by ‘fudging’ the evidence of 5th. Officer Lowe.

From testimony given by the Titanic’s 5th Officer Harold Lowe (American Inquiry, p. 381), the course from noon to the corner was 240.6° true, and the distance was 126 nautical miles (after correcting what appears to be a transposition error of two digits in the transcript of his testimony).

Titanic’s navigating officer Pitman stated in evidence to the British inquiry that the distance from Noon 14th to the corner (42/47) was 110.5 miles. He also stated that the course alteration was made at 5:50 p.m. at least 10 miles to the south and west of the corner.

15173. (Mr. Harbinson.) I will observe your ruling. (To the witness.) Do you know at what time the course that the steamer was to take was mapped out that day?
- Yes, noon.
15174. And, so far as you know, was the steamer's course deflected at all from the course that had been marked out at noon; did it vary to the south, or in any way from the course which had been marked out at noon?
- Yes, I considered we went at least 10 miles further south than was necessary.
15175. Do I understand you rightly that in marking the course at noon, the course was marked 10 miles further south than you considered necessary?
- No. We had a certain distance to run to a corner, from noon to certain time, and we did not alter the course so early as I anticipated. Therefore we must have gone much further south.
15176. When did you alter the course?
- 5.50.

At the noon 14th position,42° 54.3'N, 44° 50'W, Titanic was on a course of S 85° W [S 62° W true].which took her to the position of 41° 55' N, 47° 20.8' W at 5:45/5:50 PM .The course was altered to N 71°W (266° true) passing south of the Customary track to Nantucket LV.

If course of S 85° W [S 62° W true] is run from your noon 14th position of 43° 02’ N, 44° 31’ W. {126 miles x 060.6° from Corner )to 5:45/5:50 PM the course alteration position is 42° 02.4'N, 47° 02.7'W (3 miles NW from the corner). The course 266° from this position leads north of the Customary track to Nantucket and 22 miles North of Nantucket LV. This is ridiculous!

 

[Bill West]

Capt’n, in this paper the course is trimmed at Sunday noon to 241TC. Inside the calculations it is more exactly 240d 33.5’ per Lowe which at 126 miles is about 0.1’ from 42/47. But Sam, maybe the 2nd para should clarify the distinction between The Corner at 42/47 & 126 miles and The Turn given in the 2nd from the last para as 4.5 miles southwest (and 11-12 minutes later) at 5:50pm. Because the delay is well known and because I put all of this in sequence on a spreadsheet to understand it before I tried evaluating it, I had readily caught the distinction but maybe it needs emphasis.

As far as Lowe’s 126 miles Sunday noon to The Corner versus Pitman’s 110.5 I too have tabulated this trip and have drawn yet another set of conclusions. But Sam’s advantage over me is that he has published, if I catch up then maybe I can challenge his points and we can reduce them to a sounder conclusion. In the mean time however I can’t fairly criticize his detailed paper when my counterpoint is an incomplete paper. At least not as far as making logical sounding argument segments when they might easily fall apart if I was forced to show them all connected together and fitted with all the other pieces of known evidence.

For instance I’m using a northward drifting course that makes Friday’s turn at noon and passes straight through the 7pm LaTouraine message on its way to Saturday noon but I hardly expect any one to believe it because it depends on several other points that I have not presented groundwork for.

Bill

 

[David G. Brown]

Navigation is not about "where we've been," but rather "where we are going." In 1912, however, it was always necessary to know where you were in order to know how to get to where you were going. This requirement explains the need to obtain regular position "fixes" using landmarks when available and the stars when offshore.

The real problem in understanding Titanic's interrupted voyage is not the great circle course. To understand the last 6 hours the only critical piece of data is "where did the ship think it was at the start of the rhumb line for New York?"

The reason for this question being paramount is quite simple. The start of the rhumb line marks a new departure point for the ship's navigation. Nothing prior to that moment applies with regard to the dead reckoning that was done in the ship's chartroom or the captain's navigation office.

What time did they take departure on the rhumb line?

What geographic coordinates did they use for departure on the rhumb line?

Note that I have not asked the actual location or time, but rather the time and coordinates the ship's officers used. In dead reckoning there is always some difference between where you think you are and where you really are.

In my estimation, there are six sets of coordinates and one line of longitude which must be placed on the ship's rhumb line DR track to get an historically correct view of what the navigating officers though happened that night. They are:

1. Departure for the rhumb line (time and coordinates).

2. 7:30 p.m. stars.

3. 8:00 p.m. dead reckoning.

4. Dead reckoning of accident.

5. Boxhall's CQD coordinates.

6. Smith's CQD coordinates.

7. Longitude of midnight, April 15 in ship's time must be 24 hrs 47 minutes west of midnight longitude for April 14th ship's time (ATS).

Yes, I have a solution for all of this. And, yes, as everyone probably expects Sam disagrees with me. But, we both pretty much agree on #1 above.

From departure, 7:30 p.m. stars must lie on the rhumb line course. And, the 8 p.m. DR must lie 30 minutes west of stars on the same line. That much is obvious. From then on, things become a matter of interpretation. I have found two acceptable (to me) explanations for the other points. Sam has his version. Haven't seen his work, but I'll bet Bill West comes in with a fourth possibility.

-- David G. Brown

 

[Samuel Halpern]

Navigation is not about "where we've been," but rather "where we are going."

Not so. Navigation is about "where you are, where you were, and where you are going." You cannot get to where you want to go unless you know where you are, or think you are. And until you get a fix, where you think you are depends on where you were.

The course to steer from point A to point B (e.g., the noon position to the corner) is not necessarily the course line between the two points. Compensation for an estimate of the local current can be factored in to get an estimated position, not a DR point. In aviation pilotage we do this all the time based on estimated winds aloft and corrected if need be based on measurement once in flight. It does not surprise me that there is a slight difference in heading Vs. course line.

The 126 miles from noon to the corner was the remaining distance to the corner after the ship had completed 1549 miles of travel since leaving Daunt's Rock. The transcript of Lowe's testimony had "162" miles to the corner from noon which is obviously an error, and Capt. Collins knows that. That mileage needed to be corrected. I got 126.1 miles remaining to the corner after the ship traveled a total distance from Daunt's Rock of 1549.4 miles taken over the locations I gave in that table. 126 is also what you get by transposing the last two digits in the 162 from the transcript of Lowe's testimony to get 126 which agrees with remaining miles to the corner based on total distance already traveled till Sunday noon.

As far as Pitman saying that there was 110.5 miles to corner from noon, I don't recall him saying any such thing. I do recall him saying at that British Inquiry that he thought they would be up to the corner at 5 pm but ran past that to 5:50 before altering course. (He told a different story at the American Inquiry you know.) But I know how you, Capt. Collins, got those 110.5 miles. You just took 5 hours and multiplied by 22.1 knots and going along the reciprocal of Lowe's course to the corner. The problem with that is Pitman was wrong about the expected time for being at the corner, and Boxhall even refused to confirm Pitman's time, although he also said they turned later than what he expected.

Now assuming we take you 110.5 miles from the corner as the noon location, then you have a big problem with the total milage run since leaving Daunt's Rock. If you add that up the individual mileage for each day you get 484+519+546 = 1549 miles. But even following a perfect GC path from Fastnet to your noon location and adding the 55 or 56 miles from Daunt's Rock to Fastnet, you will get a MINIMUM of 1563 miles, or 14 miles greater than what was the ship actually did. (The individual daily runs of 484, 519, and 546 are not only in Pitman's memo but can be confirmed by the accounts of others as I referenced in footnotes 11, 12,and 13). And that 14 miles is the absolute minimum overshoot in total mileage you can get if you hold onto that 110.5 miles that you derived from Pitman's BI testimony.

The reason Pitman said what he did (as I fully covered in my 2-part THS Commutator paper, "A Minute of Time") is because he apparently worked the problem backwards because the ship could not have traveled to the CQD spot by 11:40 if they turned the corner at 5:50 pm. To make things fit, he took the CQD position of Boxhall as a given, went backward at 22 knots for 5 hours 50 minutes (the time interval from 5:50 pm to 11:40 pm) on the reciprocal of 266° (which is 086°), and then went on the reciprocal of 242° (which is 062°) also at 22 knots for another 5 hours and 50 minutes to get back to 12:00. That location is about 111 miles from the corner which would have been about 15 miles of further travel from Daunt's rock than what was recorded. This is no surprise to me since the CQD location is a good 13 miles of travel beyond where the wreck site is. If you start with bad data (i.e., the CQD location), you end with bad data (i.e., the wrong noon position).

The problem is that everyone accepted Boxhall's CQD location to be absolutely correct. The wreck on the bottom of the Atlantic proves otherwise.

How Pitman got his erroneous noon location is shown in the chart below.

Also notice by using these DR tracks how the ship does not pass through the corner but passes about 5 miles north of it at 47° W. This of course does not include the affects of current and in no way represents the track of the ship over ground.

 

[David G. Brown]

Navigation really has only one requirement: predict the future course (and sometimes speed) of a vessel endeavoring to reach a specific destination. There is no other purpose for navigation in the life of a ship other than determining how to get where it's going. We should not confuse the data necessary to perform that predictive function with the actual purpose of the exercise. In 1912 it was impossible for a navigator to know the course to a destination without knowing the ships location first. That is, even Joseph Boxhall with his nav training could not find his way anywhere if he did not know the latitude and longitude of his starting point. Dropped in the middle of an ocean, he would have been lost despite all of the accouterments of a navigator. (Today, the GPS system “knows” where the satellites are, so can find a lost navigator, but that was in the future beyond Boxhall’s lifetime in 1912.) So, there was an absolute need to know at all times the answer to the question, “Where am I?”

Surprisingly, for the importance of the "where am I?" question to under way navigators (prior to GPS) those working in 1912 chartrooms almost never knew exactly where they were. The best they could do is calculate where they probably were a few minutes or hours ago. The one exception was taking departure at the very start of a voyage when the time a ship passed a known landmark gave an accurate “real time” fix. After that, everything was an approximation. Even star sights did not fix the ship where it was, but at best approximately where it was. A round of celestial sights took time, so the first sight of a series was customarily “advanced” to the time of the last. Then, the computations began. It might be minutes or hours before the whole set of sights was reduced to a position somewhere behind the ship.

To keep as tight a handle on “where am I?” as possible, dead reckoning was employed between fixes. This is a sort of human-powered inertial navigation system. It is based on predicted speed and predicted direction from the last fix. The trouble is that ships don’t always go as fast as they should or in the direction they are heading. Currents and windage play havoc with dead reckoning. This is why dead reckoning was (and continues to be) discontinuous. The navigator plots carefully from one fix to the next, but knowing the DR track line is never accurate. It always produces a DR position in error some distance from the better position obtained by the next fix. What happens then? Well, the navigator forgets everything that he has done and starts over again with the new fix as the origin for a new DR plot.

This discontinuous nature of dead reckoning due to its built-in errors must be accounted for in trying to recreate the ship's track from Daunt Rock or anywhere else. The ship's DR would have been restarted several times daily depending upon the availability of star sights. Had a graphical track line been kept in Titanic, it would not be a smooth, continuous pencil line from start to wreck. Rather, it would be a series of discontinuous lines, each one originating at a fix but terminating in open ocean some distance from the next fix.

However, no such track line exists because in 1912 they did not plot course lines on a chart as we do today. DR positions were created entirely through a set of mathematical processes usually lumped together (not quite correctly) as "The Sailings." Latitude and longitude were determined directly without charts, protractors, and parallel rulers. A disadvantage of this system is that it deprived the navigator of a graphic representation of the ship’s progress. Often, this visualization makes navigational errors more obvious than if pure numbers are presented as tiny pencil crosses on a chart.

There is no doubt in my mind that Sam is correct about much of the "navigation" put into the record by the various officers. A lot of things appear to have been ex post facto creations to smooth over troublesome areas in the story. I fear that Sam is making the same mistake on the chart he presented. But, before Sam and I start to cross dividers, the plot he presented is the same as I was drawing until about six months ago. It was only then that I realized that traditional re-creations of Titanic’s dead reckoning do not take into account the single most important set of coordinates; nor do traditional forensic plots begin with the concept that navigation is predictive, not historic in its nature.

The key piece of information missing from Sam's plot and from the plots that I was doing is the first set of CQD coordinates. Titanic sent two different locations, not one. Boxhall's famous set was the second. But, the ignored first set of coordinates given by Captain Smith to the Marconi operators, 41 44 N; 50 24 W, is the more critical to understanding of what took place.

Make no mistake, both sets of coordinates are "incorrect" with regard to the actual location of the wreck. But, that conclusion hides the truth. Neither one was meant to be the location of the ship, but rather both were predictions of where Titanic "ought to be" at some specific time that night. To understand the two sets of CQD coordinates you must understand what the navigators who created them were predicting. To my mind, the longitude of the first set of coordinates from Captain Smith strongly indicate it was a prediction of the ship’s midnight position. The second set by Boxhall was a prediction of where Titanic should have been 20 minutes earlier at the 11:40 p.m. time of the accident.

I have come to believe the two CQD coordinates are separated by the element of time. Specifically by 3/10ths of an hour or 18 to 20 minutes.

An axiom in navigation is that two locations separated by time for the same object represent a line of position. That is, if Titanic were to have ever been at those two locations at times separated by about 20 minutes, it could have done so only by steaming in a straight line from one to the other. Like it or not, the two CQD positions tell us that the men who created them thought Titanic was on a course from Boxhall's 41 46 N; 50 14 W to Smith’s 41 44 N; 50 24 W.

The direction of travel contained within the two CQD coordinates is near enough to 255 degrees to make no difference. The distance on my plot between the two coordinates is about 7.3 miles, which in 20 minutes requires 22 knots--exactly the speed Boxhall said Titanic was making turns for at the time of the accident.

So, using evidence in the form of the two undisputed sets of CQD coordinates, it appears that Smith and Boxhall thought the ship was steaming on a 255 course at 22 knots. The speed fits the historical record of Boxhall’s testimony. But, why 255 degrees? That was not the course to New York.

To answer that question we have to ask another one. What was the proper course to North America? I believe it was about 266.5 degrees from "The Corner." Simple subtraction shows the 255 degree line between the CQD coordinates is about 11.5 degrees different from the proper course. Anyone with “old school” navigational experience should not have bells going off in his head. 11.5 degrees is essentially one compass point. And, in 1912 it was still customary to give steering orders in points, not degrees as we do today.

If we take the line of position back to where it crosses the 266.5 track line, what does that tell us? Well, at 22 knots this crossing lies 5:40 from "The Corner." Quartermaster Rowe said the ship turned "The Corner" at 1745. The officers spoke of 1750 or 1755. Taking the middle number, 1750, and adding 5:40 to it gives a time for the crossing of 2330 hours ATS, or 11:30 p.m. in everyday speech.

So, using the historical record we have found that the two CQD positions when put into context with the ship's course and speed from "The Corner" indicate something momentous: Titanic changed course one point to the south at 11:30 p.m. ATS.

NO, this course change did not result in the accident. Or, at least it did not directly cause the accident. The importance of this revelation is that it shows Titanic under Captain Smith did not go steaming pall mall into an ice field. The evidence that has been on the record for almost a century shows a completely different story from the slanderous account of a sleepy captain letting his ship speed headlong to its doom.

Turning one point to the south at 11:30 p.m. ATS shows a prudent Captain Smith taking an active hand in the safe conduct of the voyage. He was intended to take his ship around the southern end of the ice field. Such an action ties in perfectly with Boxhall's testimony about the captain doing a lot of plotting during the hours leading up to the accident. Smith did not plot ice for the enjoyment of making tiny “X” marks on the chart. He was trying to predict the safe way through the ice danger while at the same time keeping the voyage as short as possible. (Remember, his boss Ismay wanted a fast trip.)

Why an 11:30 p.m. course change? Well, because of the requirement to check the steering compass against the standard compass every half hour. The most efficient time to make a course change would have been when an officer had to go to the compass platform anyway. Hence, 11:30 p.m. allowed the course change and compass check to be combined for convenience.

Now the question remains, "Why the westerly error in the two CQD positions?"

Sam and I both know that is a matter of time.

-- David G. Brown

 

[Samuel Halpern]

"In 1912 it was impossible for a navigator to know the course to a destination without knowing the ships location first."

Why just 1912? The course to a destination has meaning only relative to some location you are at or believe you are at.

"Dropped in the middle of an ocean, he would have been lost despite all of the accouterments of a navigator."

Not true. You don't need GPS to know where you are if dropped in the middle of the ocean. I'll take a sextant, chronometer, nautical almanac, some paper and a pencil and the ability to get a set of stars. I won't get my position to 50 meters, but within about a nautical mile may be possible if the instruments are accurate enough.

"knowing the DR track line is never accurate."

The DR track is accurate if plotted correctly. What is not accurate is saying that the ground track will always match the DR track. I think that is what you meant.

"Had a graphical track line been kept in Titanic, it would not be a smooth, continuous pencil line from start to wreck. Rather, it would be a series of discontinuous lines, each one originating at a fix but terminating in open ocean some distance from the next fix...A disadvantage of this system is that it deprived the navigator of a graphic representation of the ship's progress. Often, this visualization makes navigational errors more obvious than if pure numbers are presented as tiny pencil crosses on a chart."

These fixes were plotted on charts that had the intended tracks laid off on them. They also marked off DR positions such as the 8 pm DR per IMM rules. What they didn't do is used a graphical method to get these DR positions. Connecting the fixes would give you the course made good, not necessarily the exact course traveled over ground.

"I fear that Sam is making the same mistake on the chart he presented...The key piece of information missing from Sam's plot and from the plots that I was doing is the first set of CQD coordinates."

What mistake did I make, and on what chart are you referring to? If you are referring to the plot I posted above, that was purely to illustrate how Pitman derived a noon location 5 hours from the corner. It has nothing to do with the 1st CQD location coordinates which was noted as being erroneous when Boxhall's position was first transmitted.

"To my mind, the longitude of the first set of coordinates from Captain Smith strongly indicate it was a prediction of the ship's midnight position. The second set by Boxhall was a prediction of where Titanic should have been 20 minutes earlier at the 11:40 p.m. time of the accident."

You are entitled to your opinion, but I believe the first CQD position was also intended to represent the position of the ship at the time of collision but worked differently than the way Boxhall did, and included an oversight error of 23 minutes of time which is why it was further west than Boxhall's position. Boxhall's position, which was referred to as a "corrected position" when it was first sent out 10 minutes after the initial CQD was sent out, was worked for a collision time of 11:46, not 11:40, and worked directly from the 7:30 star fix taken by Lightoller and Pitman. I covered this fully in my 2-part THS Commutator article, "A Minute of Time" and see no need to go into all the details here.

"Sam and I both know that is a matter of time."

Yes, a minute of time is all you need, or as Dave Gittins suggested, accidentally taking data from the wrong column in a transverse table.


The paper being discussed on this thread concerns the intended track of the ship from Daunt's Rock to Ambrose, estimated noontime positions for the ship up to and including Sunday April 14, the clock adjustments that were made during the voyage each day out, and the speed made good over ground for each day's run. The article posted here on ET was the same that I wrote last August for the ITHS's White Star Journal. If I were to add anything new to the article it would be the probable location of Titanic's final stopping point late Sunday night. That point I estimate to be at 41° 47' N, 49° 56' W to the nearest minute of arc, consistent with the MAIB Reappraisal report.

 

[L. Marmaduke Collins]

Posted on Wednesday, February 28, 2007 - 6:37 pm:

Referencing ET article Keeping track of a Maiden voyage. ....what is the logic for adding 126 miles to the route distance of 1492.8 miles (from off Fasnet to Noon 14th Memorandum of Mr. Pitman) making a total route distance of 1618.8 nm ?

The unsigned and undated "Ship’s Run Data", presented at the United States Senate Inquiry and purported to be a memorandum of Third Officer Herbert Pitman , SS Titanic, in my opinion contains too many discrepancies to have been authored by a highly certified and competent ship’s navigator of Third Officer Pitman’s calibre.

 

[Samuel Halpern]

G'day Dave Gittins. You wrote,

"I took over the headphone from him, and he was preparing to retire when Capt. Smith entered the cabin and told us to get assistance immediately. Mr. Phillips resumed the phones, after asking the captain if he should use the regulation distress call "C Q D." The captain said "Yes," and Mr. Phillips started in with "C Q D," having obtained the latitude and longitude of the Titanic."

In other words, Phillips waited for Boxhall to give him the position, as Boxhall described, but the first transmission may have been incorrect.

I don't see where Bride gives any hint as to where Phillips got the coordinates from. Since he mentions only Smith being there it would be natural to assume that it was Smith himself who gave those coordinates to Phillips right then and there.

I think you are reading more into what Bride wrote only because you know that Boxhall had worked up the coordinates that were eventually sent out as a "corrected position" at 10.35 NYT. But the position that went out 10 minute earlier was not the Boxhall coordinates. They were picked up by the Mount Temple, Ypiranga, and Cape Race with 50° 24' W longitude, yes 10' further west. There can be many explanations for that especially if the 7:30 fix may was put down in error in the first place do to single systematic error which affected all star lines of position, an error that may have been been made by Pitman, not Boxhall. Well, you know where I'm coming from on this.

Captain Collins:

Senator PERKINS. I suggest that these papers be put in the record. This is a list of the survivors [indicating] and this other paper is the memorandum made by Mr. Pitman in regard to the ship's run.
The CHAIRMAN. They may be included as part of the record.


Unsigned or not, it was submitted on April 24, 1912, at 2:30 pm. and entered as being made by 3/O Pitman and put into the record. That is not to say there weren't errors in that memorandum, but the daily mileages run can be cross checked with other sources, and these have been.

And as far as those "162 miles" to the corner from Lowe not being a transcription error in transposing 2 digits, consider what Lowe was telling Sen. Smith. He said he used a speed of 21 knots taken over 6 hours to the corner. Do the math. It comes to 126 miles. He obviously came up with that speed by doing the opposite, dividing 126 by 6 which is a simplification of the actual time from noon to the turning point of 5 hrs 50 min. He just wanted Smith off his back in that discussion about speed. The 126 miles is also the remaining miles to the corner after subtracting the total mileage run to noon Apr 14. So we have two different ways that gets to the same result.

Dave Brown, welcome back. I have quite few comments on what you wrote as you probably expect. But I'll have to save it for now. But as you know, I have a few other things to deal with at the moment.

 

[David G. Brown]

I know Sam has comments about what I wrote. He is, indeed, the loyal opposition.

One thing I do want to repeat: my view of the two sets of CQD coordinates contain the same "error" and are both based on the same data. Although both were "wrong" for the actual location of Titanic, the problem was not with 7:30 stars or any navigational computation. In fact, the first CQD position represents an accurate prediction of Titanic's midnight (change of civil date & time) location. The second set of coordinates is removed by 20 minutes at 22 knots, which by definition is 11:40 p.m. in the time reference of the first set.

Quite obviously, there was an "error" made. This is demonstrated by the distance from either set of CQD coordinates to the wreck site. This "error" was also noted on 15 April 1912 by Mt. Temple.

My contention is that the first set of CQD coordinates were known to be the ship's predicted midnight. Captain Smith chose to use them for very logical reasons: 1.) he had them and did not need to waste time computing; and 2.) he wanted ships to start his way, knowing a better position could be sent later to direct rescuers closer to their location.

The "error" was in verbal communication between Smith and Boxhall. As such, it falls on the captain's shoulders as senior officer issuing the order to recompute the ship's position. I believe Boxhall had lost track of time during his two visits into the bow. Smith said he used "midnight" as for the first coordinates, and Boxhall assumed it was the 12:00 shown on the bridge clock. In the natural confusion of an emergency, Smith did not require Boxhall to repeat back the entire order. Smith left thinking Boxhall was using the predicted midnight, while Boxhall thought he was using bridge time.

The result was that Boxhall carefully "backed up" the predicted midnight to 11:40 p.m. As I said earlier, in the normal course of events Boxhall should have created the midnight prediction, so by simply "backing up" 20 minutes he based his new work on that existing computation. This meant he in fact used 7:30 stars for his CQD coordinates.

However, because by definition midnight marked the start of 15 April, Boxhall's CQD coordinates were not for Titanic's location but for 11:40 p.m. in 15 April time. That was somewhere about 23 minutes east of midnight, or about 23 minutes west of the actual wreck site.

As far as the speed goes, I don't know what the shafts were turning. Nor do I know what the speed through the water was. Nor do I know what the speed made good was. And, I might add that no one else has that data, either. What we have is a measured wreck position and sworn testimony from Boxhall about the speed he used in his dead reckoning. From the juxtaposition of "The Corner" and the two CQD positions, it does appear that Boxhall spoke truthfully about 22 knots being used for DR purposes; and that 22 knots was very close to the ship's actual speed made good. The difference between SMG and DR is in the 0.5 knot range indicating the head current expected by Boxhall and predicted in Bowditch.

Now, I have to return to editing a book about ponton boats and a separate effort on making money with a captain's license. Those who came to the last Titanic in Toledo event will fully understand how I came into this work.

-- David G. Brown

 

[Samuel Halpern]

David. If we are to follow your theory we must all work from the same page, or should I say plotting sheet. You said you the course change was made at the corner, 42°N, 47°W, at 5:45 to a course 266.5 true. Forgetting the little detail that record had the turn at 5:50 to 266 true, if we take what you said and go from the corner on 266.5 true you never get to the point that you call "the crossing" at 41°51'N 49°43.6'W. Your "crossing" point is on a line 265.8 true, not 266.5, and located 122.5 miles from the corner, or 5 hours 34 minutes at 22 knots. If the the turn was made at 5:45, then that point is reached at 11:19 ATS, not 11:30. More importantly, it doesn't fall on the 255 degree line extended through the two CQD positions. It's off to the east. (You must have been using a very thick pencil point.

)

So as a friend, let's fix the numbers in your scenario since I know exactly where you are coming from.

Let's go backward on the reciprocal of 255, or 075 true, from the initial CQD at 41° 44'N, 50° 24'W for 1 hour 17 min (that's 24:47 - 11:30 = 1:17) at 22 knots. That is 28.2 miles. That get's you to 41° 51.3'N, 49° 47.5'W at 11:30 ATS, what you call "the Crossing." That location is 125 miles from the corner at 42N, 47W on a line 266.0 true. (I'm using a mid-latitude method for those following this.)

At 22 knots, it takes 5.68 hours (which is 5 hours 41 minutes) to go 125 miles from the corner. Subtract that from 11:30 and you get a 11:30 - 5:41 = 5:49 ATS turning time at the corner (which is very close to the 5:50 written in the night order book) in this scenario.

So now that we got all that down, let's see what you are saying.

Boxhall computed a DR position for 24:47, the start of 00:00 in Apr 15 time, and Smith put it on the chart sometime that night, I presume some time after 10 pm when Boxhall said he finished working up the 7:30 fix. Getting to that position included a 1 point planned course change at 11:30 from 266 to 255, to avoid ice. After the accident, Smith gives this 24:47 location to Phillips knowing that it is not right, but then asks Boxhall to work up a corrected position to take to Phillips. He tells Boxhall he gave Phillips the position for "midnight" which Boxhall forgot was midnight the start of April 15 (which was 47 minutes beyond 24:00 using April 14 time). So Boxhall takes the charted position, thinking it represents 24:00 ATS, and backs it by 20 minutes to 11:40, which is 7.33 miles along 075 true which he then rounds down 41° 46'N, 50° 14'W, and gives that to Phillips to transmit.

So Dave, do I have your scenario described correctly on how these two CQD locations came about?

 

[L. Marmaduke Collins]

Do the math. It comes to 126 miles. He obviously came up with that speed by doing the opposite, dividing 126 by 6 which is a simplification of the actual time from noon to the turning point of 5 hrs 50 min.

A more careful perusal of ET article “Keeping track of a maiden voyage” shows that the course and distance from off the Old Head of Kinsale to departure off Fastnet are inaccurate, and in fact puts Titanic on a course for a grounding on Fastnet Rock. The correct course is 252° distance 42 miles , making the departure off Fastnet 51° 20' N, 9° 36'W . Consequently, the noon positions calculated for April 12th , 13th and 14th are inaccurate.

On the basis of the Memorandum, purported to be of 3/Officer Pitman, the noon position April 14, 1912 is 43° 04.7'N, 44° 26'W, 131 nautical miles ( not the fudged 126.1 nm) 060.40°from the corner 42° N/47° W.

From the noon 13th position to noon 14th position the course is calculated as 242° T ,and at noon 14th the course is altered 1° (one degree) to port for course 241° T. This is a contradiction of the evidence of QM Rowe who stated in evidence that up to the time of 5: 45 PM April 14th the course was S 85° W by the steering compass ( 242° T) 5:45 PM 14th the course was altered to N 71° W by steering compass (266°T)

Steering 242° T from noon 13th position to 5:45 P.M. April 14th would put Titanic’s alter course position at 42° 05'N, 46° 57.8'W.(5 miles north of the Corner) A course of 266° T from this position would put Titanic on a track 24 nautical miles north of Nantucket LV.

Do the practical navigational calculations!

 

[Samuel Halpern]

Capt. Collins. Taking departure off Fastnet 3 miles south of what I used makes almost no difference in getting to the LAN locations I gave in my article.

Regarding the evidence, Rowe gave the steering compass course as S85W before the course was altered. You said that corresponds to 242° true.

What I said in my article was the "intended" course from noon to the corner "rounded to the nearest degree" was 241° true. The more precise direction would be 240.6° (see footnote 16). Lowe actually said from memory "60º 33 1/2' west" which is taken to mean S60°33.5'W, or 240.56° true.

Now we know from Lightoller that N71W (289°) on the steering compass corresponded to S86W (266°)true. The difference is variation plus deviation error which is 23° for that particular heading. Applying the same correction for a steering compass course of S85W (265°) gets 242° true as you say. But is this the correct correction to apply?

The 23 degree correction, which comes from Lightoller was applied after the ship altered course from a compass heading of 265° to 289°, or after a starboard turn of 24 degrees in the ship's steering compass heading. But what is the correction that should be applied to go from compass heading to true heading before the turn was made?

Looking at detailed data from an Olympic 1931 voyage on March 29 westbound, we find the ship was heading from noon to 4:40 pm on a heading of 243° true (by gyro compass). The steering compass course was written down as being S89W (269°) and the deviation for the steering compass was written down as 1.25° E. At 4:40 pm they altered course (at 43° 00'N, 50° 00'W) to 261° true on a steering compass course of N76W (284°). The deviation error for this compass course was recorded as 3°E. So we see the ship's heading was changed to starboard by 15 degrees by steering compass which resulted in a true heading change of 18 degrees. Part of the 3 degrees of difference between the two was in the deviation error for the two different headings, a deviation difference of 1.75° for only a 15° course change. The remaining 1.25° difference in this example would be the change in variation from noon to 4:40 pm.

So be careful in what you assume when converting from compass course to true course, especially when applying a correction that may not be valid to the old course heading. A compass heading of S85W as Rowe said could very well have corresponded to Lowe's 240.6° true. As we have seen, a deviation error change 1.5 degrees for a course change of only about 25 degrees is not only possible, but has been recorded in the Courses on Board book of Titanic's sister ship on her 200th voyage from Southampton to NY.

Welcome to the world of real practical navigation.
Cheers,

 

[L. Marmaduke Collins]

Capt. Collins. Taking departure off Fastnet 3 miles south of what I used makes almost no difference in getting to the LAN locations I gave in my article.

Based on the purported Pitman Memorandum and real practical navigation your positions for Noon 12th, 13th and 14th are erroneous.

Noon 12th should be 50° 06'N, 20° 40'W
Compare with your 50° 06'N, 20°43'W
A discrepancy of 2 miles .

Based on your track line of 249° x 402 miles:
Noon 13th should be 47° 21'N, 33° 03.5'W
Compare with your 47° 22N, 33° 10'W
A discrepancy of 4.4 miles.

Based on your track 242° x 546 miles
Noon 14th should be 43° 04.7'N, 44° 26'W Distance to Corner = 131 miles
Compare with your 43° 02' N, 44° 31'W Distance to Corner = 126.5 miles
A discrepancy of 3.7 miles

If, as you assume, 240.6° T = S 85° W Comp. the 5:45 PM (5:50PM) course alteration to 266° (N71°WComp) was made at position 42°03'N, 46° 56'W, taking Titanic north of the customary route and 22 miles north of Nantucket Lv.