How Far South did the Titanic Reach?

Mar 22, 2003
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Haddock sent this telegram to Rostron. But why should Rostron do any calculation about mean solar time of Haddock's position?
He didn't. The position given in that message from Rostron to Haddock on April 15th was Carpathia's position, not Olympic's. Rostron was simply informing Haddock where his ship, Carpathia, was at a specific point in time, and more importantly, where he was headed. Unlike others here on this forum who somehow knows all about the conversation that took place between Rostron, Lightoller and Boxhall, I only pointed out an observation that produces a very interesting and very suspicious coincidence. Nobody can deny that Carpathia's position given by Rostron in that message to Haddock is precisely 3h 27m behind GMT; the exact same time difference we find in the message he sent to Haddock just 45 minutes later when he gave the time Titanic foundered in ship's time and GMT.

It is all too easy to assume what some people knew or didn't know. But I do not for a moment believe that Rostron would ask what the time difference was between Titanic time and NY time. As Jim Currie points out many times here, the only time that mattered to ship's officers is ship's time, by which they stood watch and ate and slept, and Greenwich mean time by which they used to navigate. Rostron was clearly interested in what GMT was when it was 2:20am ship's time on Titanic. Mean solar time at the Ambrose light vessel was irrelevant, so too was mean solar time for New York city. Sen. Burton's remark was not only a bit strange, but also incorrect. Mean solar time for NY was and still is 4h 56m behind GMT, not 4h 57m as Burton announced. Mean solar time at the Ambrose channel light vessel, the official arrival/departure point for ships going in and out NY harbor, was 4h 55m behind GMT and appears in Reed's table. But Sen. Smith asked what the time was in NY when Titanic foundered so he could put it in the record. Notice that he told Pitman that he was given ship's time and Greenwich time which he just happen to get from Lightoller. He also answered his own question after Pitman told him to take 5 hours off Greenwich time, but Smith wanted Pitman to work it out and gave Pitman the foundering time in GMT that Lightoller gave him just a few minutes earlier after Pitman asked him "Give me the Greenwich time, please?" What's funny is that Pitman got 11:47 by subtracting 5 hours from 5:47, something Sen. Burton immediately noted and Sen. Smith corrected to 12:47. The exchanges between the three, Pitman, Smith and Burton, is almost comical.

I have a suspicion as to how that 3h 27m difference came about, but I'll save that for another post. Just note that it never surfaced at the British inquiry which decided on something totally different altogether.
 
Nov 26, 2016
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Hello Marcus.that her forward progress was being hampered by a 1 + knot current. During the run from Noon toward the planned turning position named The Corner, the head current that hampered her also pushed her to the southward of her intended course. The result was that at 5-50 pm., when she turned onto her course for New York, she was about 6.5 miles ENE of The Corner.
Between 6 pm and 8 pm. her speed began to build so that between 6 pm and 8 pm in the evening., her average speed increased to 21.4 knots. After the conditions became flat calm, her speed increased to 22.5 knots and she maintained that speed until she hit the iceberg.
There is absolutely no doubt that Titanic's clocks were retarded by 24 minutes before she hit the iceberg.
 
Nov 26, 2016
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Hello Jim,
many thinks for that post #80, up to now I did not realize that Lowe referenced to the log taken at 6 o'clock, somewhow I have overlooked this.
But some objections come up.

Just to fix the basic conditions first.
The noon position is 126 miles before the corner, based on noon observations, as i understood Lowe's testimony. The place to hit the ice berg, you assume nearly the same as me, 41-45' N and 49-56' W is 132 miles behind the corner. These two add up to 258 miles.

Either you or Sam told me, if the ship was heading to the corner, she must not necessary pass through it. Agreed, of course I am aware of this.
But because of the flat angle of 25 degrees the point can vary some miles without considerable change of the sum. 5 miles to NW make 256 miles, 5 miles to SE make 260 miles. So we have chance to play some games.

Now about the log. The log indicates miles travelled through the water.
From Saturday noon to Sunday noon Titanic travelled 546 miles over ground. Speed was 22.1 knots over ground average.
Assume a gulfstream of 0.4 knots this would make 22.5 knots through the water. Hichens took the log at 10 pm. It indicated 45 miles in 2 hours, 22.5 miles through the water. There we are! I don't know why Hichens had to give a separate testimony about this, there is no reason to get upset. Titanic made this 25 hours the day before.

Rowe read the log after collision, it showed 260 miles from noon to collision.
This works out either 22.2 knots in 11,7 hours, with clocks not retarded or 21.5 knots in 12.1 hours, with clocks retarded. As the revolutions were not changed, may be one engine doing 76 rpm iso 75 for some time, i would exspect the log should always indicate the same speed through the water. The results would rather suggest there was no clock retardation, for the first.

Now we come to Lowe. The log indicated 126 miles at 6 pm, speed 21 knots through the water.
When i have a look on my map at the corner and to the NE of it, it shows northatlantic current of 0.4 to 0.8 knots. This will reduce the speed even to let's say 20.5 knots.
Here my problem with the log. If revolutions are unchanged, why does the same log indicate 21 knots in the afternoon and 22.5 knots after 8 pm? Can this be explained by changed weather conditions?
You found the turning point 41-57 N and 46-52 West. I am wondering why this is south to the corner? Probably your current is directed to East, the current in my map is going ENE, right opposite to Titanic's course.The two branches before and after the corner add up to 260 miles.

As I am skeptical about the speed of 21 knots, I would like to play four cases:

Speed over ground from 12 to 8 pm: 20.5 knots
distance travelled: 164 miles
remaining distance: 96 miles
Speed from 8 to 11.40 respectively to 12.04: 25.9 / 23.4 knots

Speed over ground from 12 to 8 pm: 21.0 knots
distance travelled: 168 miles
remaining distance: 92 miles
Speed from 8 to 11.40 respectively to 12.04: 24.9 / 22.4 knots

Speed over ground from 12 to 8 pm: 21.2 knots
distance travelled: 170 miles
remaining distance: 90 miles
Speed from 8 to 11.40 respectively to 12.04: 24.3 / 22.0 knots

Speed over ground from 12 to 8 pm: 21.5 knots
distance travelled: 172 miles
remaining distance: 88 miles
Speed from 8 to 11.40 respectively to 12.04: 23.8 / 21.5 knots

Indeed we get realistic results with retarded clocks only.
With 21.2 knots on the branch before the corner we meet well the 22 knots estimated by Boxhall.
But the log should have indicated a bit more, 21.5 or so.

kind regards
Markus
 
Mar 22, 2003
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The patent log measures distance travelled through the water, not distance made good. If the speed of the ship dropped to 21 knots for a 6 hour period, then the distance through the water shown on the log would advance 42 miles every two hours when log was taken. As Lowe explained, when asked about comparing engine revolutions to the log readings,

"We ring him [the engineer] up, and we see how she is doing with the revolutions, whether she is going faster or going slower; and you will find a corresponding difference in the log."

We were told that the ship was carrying 75 to 76 rpm since noontime Saturday, and carrying 75 rpm as late as 11pm Sunday night. There was no increase or decrease in engine revolutions. We were also told that the two hour advance between 8 and 10pm was about 45 miles. We were also told that from noon to the collision the ship advanced 260 miles through the water by log. If the ship was making close to 45 miles by log every two hours carrying 75 rpm, then to advance only 42 miles every two hours between noon and 6pm the revolutions must have gone down to about 70 rpm over that time period in a corresponding manner.
 
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Aaron_2016

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The Titanic conducted a series of S-turns before she reached Queenstown. Did something similar occur afterwards which affected the real distance she travelled? Survivors also noticed the ship was listing to port on Sunday. Would that cause the ship to veer slightly off course? - Mr. Chambers - "The ship had a list to port nearly all afternoon." Would that also affect the ship's compass?



Titanicturning.jpg



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Rob Lawes

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It certainly wouldn't effect the compass. All ships compasses would have been held in a gimbled binnacle that would have ensured that it would remain horizontal in even the roughest seas.
 

Jim Currie

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Hello Marcus.

In the days of Titanic, there were different schools of thought among navigators as to the method of working DR positions. Many thought themselves to be 'modern', i.e. that it was, as they say in modern day parlance, 'cool' to use engine RMP to work-up a Dead Reckoning position.
You mention 'playing games' and 'flat angles'. That's fine, but in fact, if we want to arrive at the truth of the matter, we have to try and think like a practical navigator. For example, speed over the ground has been mentioned as an influencing factor. Nothing could be farthest from the truth. In fact, if you had made that reference to me or any other navigator back then, you would have been considered to be a 'little unhinged" since we though in terms of water. The very word ground held untold terrors for us. The term 'simple sailor' comes to mind.
5th Officer Lowe would have been considered a 'rebel' in his day. He used the patent log for what it was designed to do.. as an aid to navigation... not a scientifically accurate instrument upon which life and death depended. That attitude was prevalent at sea right up until the advent of Sat. Nav.
The evidence tell us that the patent log read o at Noon April, 14 and read 260 nautical miles a minute after impact. For the purist among us; since Titanic was making about 22 knots when she hit the ice (the combination of turning hard left and the effect of contact would have caused her speed to immediately begin to fall rapidly; this would suggest that at the moment of impact, the Patent Log read about 259.4 nautical miles. However, back to reality. Here is a little sketch I made some time ago:
Navigation on Sunday.JPG
You use the expression "Gulf Stream". If we are going to be exact, the Gulf Stream end as such at about 60 West and its ENE extension becomes the North Atlantic Current. It was the North Atlantic Current which effected the progress of Titanic. Anyone who has ever experience these phenomenon will tell you that their influence can be felt very abruptly. That's because both the Gulf Stream and to lesser extent The North Atlantic Current are relatively narrow, well defined bodies of fast moving, warm water. In the area of The Corner, it was flowing close to ENE that day. Here's is how it is described by Captain Charles Johnston who was in command of the revenue cutter "Seneca", which went out on the so called ice patrol off the Grand Banks of Newfoundland:
Limitation of Liability Hearings
"Q. And when the berg gets into the Gulf Stream , its tendency is to move in what direction under ordinary conditions, quiet conditions of water, ordinary conditions of water? A: - East between, longitudes 50 and 49, then rapidly curving to the north.region of We can get a very good idea of its northern margin if we plot the sea temperatures".

The field ice during the time of the disaster, had reached it's southern limit. The bigger bergs in that area were en-trained in the warm stream and moving eastward. These were the ones which Carpathia met with as she rushed in her rescue mission and the ones seen to the SE by Captain Lord when he was looking for survivors. These indicate the northern edge of the eastward flowing extension of the Gulf Stream.
The temperature logged by the Californian at 4 pm that afternoon when she was near to 48-30'West, indicate where the northern edge crossed the 42nd parallel. In the following chart I have plotted the information:
Temp-100m-eng.jpg

As for how I know Titanic was to the southward of her course at Noon? I calculated the Great Circle final course for The Corner. If she had been right on the prescribed line she would have been on a course of 236.5 True. In fact, she was on 241.5 True. Therefore, when they found the solar Noon position for April 14, they had to alter course 4 degrees to the right and aim directly at The Corner.
The reason why she was off course was the wind. Before Noon it was brisk from the NW...pushing her to the SE of her intended course. After Noon, when the course was set to 240.5 True, the breeze came round to the North and continued to push the ship to the south of her intended course. We know the prevailing weather conditions from the Log of the SS Californian which was in the same area around the same time. We also know that Titanic was in an ever-building, massive High Pressure area of weather thus the wind would veer through North then decrease.
 

Jim Currie

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The patent log measures distance travelled through the water, not distance made good. If the speed of the ship dropped to 21 knots for a 6 hour period, then the distance through the water shown on the log would advance 42 miles every two hours when log was taken. As Lowe explained, when asked about comparing engine revolutions to the log readings,

"We ring him [the engineer] up, and we see how she is doing with the revolutions, whether she is going faster or going slower; and you will find a corresponding difference in the log."

We were told that the ship was carrying 75 to 76 rpm since noontime Saturday, and carrying 75 rpm as late as 11pm Sunday night. There was no increase or decrease in engine revolutions. We were also told that the two hour advance between 8 and 10pm was about 45 miles. We were also told that from noon to the collision the ship advanced 260 miles through the water by log. If the ship was making close to 45 miles by log every two hours carrying 75 rpm, then to advance only 42 miles every two hours between noon and 6pm the revolutions must have gone down to about 70 rpm over that time period in a corresponding manner.
There is absolutely no evidence of a reduction in engine revolution. In fact all the evidence points to 75 rpm from Noon to impact.There is a suggestion by Lightoller that one engine may have been briefly running at 76 rpm. If it was then the Helmsman would have been very much aware of that.

In fact there is firm evidence to show that Titanic's engine speed was not altered between Noon April 14 and 6 pm that evening. Here it is:

"Senator SMITH.
Suppose the captain of your ship between the hours of 4 and 6 o'clock on Sunday, when you were off duty, had, because of information which had come to him from the steamship Californian, that he was in the vicinity of icebergs, ordered the ship to slow down, then would your point of figuring be accurate?
Mr. LOWE.
He ordered the ship to slow down, you say?...The junior officer that I relieved would have passed on the word to me before I relieved him, before I relieved the ship...We are informed of all. Wherever there is an altering of the course, we say, "She is doing so and so, and so and so." "All right." Then you are relieved...No. It is the White Star routine. The White Star Co. have regulations, just the same, in fact, as the Navy, and we all know exactly what to do, how to do it, when to do it, and where to do it. Everybody knows his business, and they do it. There is no hitch in anything."


That is standard procedure in all British Merchant Vessels, Sam.
In any case the ship slowed down therefore the run time between Noon and impact was 12 hours 4 minutes.
 
A

Aaron_2016

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Did the Titanic pass any ships (overtake them) or possibly see eastbound ships that may have recorded her position or distance from their ship when sighted? I recall the son of Mr and Mrs Straus was on an eastbound ship at the same time the Titanic was steaming westbound. Would they see each other? Here is footage of the Queen Elizabeth passing the Queen Mary. Not sure if they are in mid-ocean but is that how close ships passed each other?

Skip to 2:10




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Nov 26, 2016
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Hello Sam,
about your post The patent log measures distance travelled through the water, not distance made good...

What conclusions can we take from this? Either the revolutions where changed, or the log was slow.
With the turning point Jim has proposed the mileage travelled over ground from noon to collision was 260 miles.
This is what the log indicated. Because of the north atlantic current, 0.4 to 0.8 knots, for 9 hours, it should have indicated
4 ... 7 miles more.
How precise can a log exspected to be? It's just a screw in the water, not a gear wheel on a tooth bar.
If it lost 7 miles of 260, that's an error of 3 percent, the best what one can exspect.
45 miles from 8 to 10. Are we sure that the log was read every two hours sharp at full hour?
May be, the one quartermaster read it 2 minutes before 8, the other 1 minute after 10, than we have 3 minutes additional
elapsed time and one mile more.
Personally I would judge the revolutions were not changed, as I can not immagine any reason for that.
The ship slowed down because of gulfstream between noon and somewhat 8 or 9 p.m.
Beeing under the influence of Labrador current, which was heading to south, the ship could speed up again.
 

Jim Currie

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Hello Sam,
about your post The patent log measures distance travelled through the water, not distance made good...

What conclusions can we take from this? Either the revolutions where changed, or the log was slow.
With the turning point Jim has proposed the mileage travelled over ground from noon to collision was 260 miles.
This is what the log indicated. Because of the north atlantic current, 0.4 to 0.8 knots, for 9 hours, it should have indicated
4 ... 7 miles more.
How precise can a log exspected to be? It's just a screw in the water, not a gear wheel on a tooth bar.
If it lost 7 miles of 260, that's an error of 3 percent, the best what one can exspect.
45 miles from 8 to 10. Are we sure that the log was read every two hours sharp at full hour?
May be, the one quartermaster read it 2 minutes before 8, the other 1 minute after 10, than we have 3 minutes additional
elapsed time and one mile more.
Personally I would judge the revolutions were not changed, as I can not immagine any reason for that.
The ship slowed down because of gulfstream between noon and somewhat 8 or 9 p.m.
Beeing under the influence of Labrador current, which was heading to south, the ship could speed up again.
Hello Marcus,

The Cherub Patent Log as fitted to Titanic was actually a very accurate little instrument It was equipped with non kinking trailing rope and an external governor wheel. As you point out, it indicated a distance of 260 nautical miles at impact. Since we know where Titanic was at Noon and where she is now, we can deduce that the log supplied to Titanic was extremely reliable. You are correct in pointing out the variations in time keeping. A minute on a ship making 22.5 knots equates to a distance of 2280 feet 0.375 of a nautical mile or in the case if Titanic, 2.8 ship lengths.

There is no evidence to show that the Labrador Current was anywhere near Titanic that night. In reality, if she was able to make 22 knots at 76 rpm under normal conditions of wind, sea and swell, then in perfect conditions..i.e. new engines, clean bottom and the absence of wind, sea or swell, she would have reached her optimum speed; which in this case was 22.5 knots. You will remember that Boxhall thought that she would make 21.5 knots under ordinary conditions but 22 knots in the conditions experienced after dusk that night.
 

Scott Mills

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I think it is clear that Titanic resumed making way after the collision. We can quibble about the time she was underway after the collision (as many of you know I err on the side if 10+ minutes), but the fact is, she resumed making way. So for me the question involves knowing for how long that was or making inferences to try and discover for how long that way. Then you'll have your answer.

As for the actual course she steam after the collision, I suspect that many of the officers did not tell the whole truth in their testimony (and you really have no good reason to think they did), which complicates everything; however, at a minimum we know she did make way for some indeterminate amount of time after the collision. We also know that some sort of evasive maneuver was undertaken to avoid Titanic's collision with ice.

Leaving aside my thoughts (I've no desire to complicate the discussion)... if as most believe, Titanic steamed slow ahead as part of a damage assessment before anyone believed her to be fatally damaged, then it is easy for me (as a non-mariner) to assume that any head way after the collision would have been in a straight line from where the ship initially came to rest. Now I assume that whatever was done to avoid colliding with the ice could have very easily resulted in an alteration of the heading the ship was traveling on; ergo, you would have a non-planned course change resulting in a heading Titanic traveled along for a minimum of 5 minutes.
 
Mar 22, 2003
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Marcus, as I said, the patent log measures distance travelled through the water, not distance made good. According to Jim, however, Lowe got a distance from noon to the corner of 126 miles by taking the log reading at 6pm. Nowhere did Lowe say that he got that distance by taking the log. He did say that they could use the log to check the speed of the ship. What he did say was: "I used the speed for the position at 8 o'clock, and got it by dividing the distance from noon to the corner by the time that had elapsed from noon until the time we were at the corner." The distance from noon to the corner came from knowing the ship's noontime position and the position of the corner point. Given that the ship had run a total of 1549 nautical miles to noon on April 14th, it can easily be shown that had about 126 miles to go to reach the corner that day. (Adding 126 miles to the 1549 already travelled gives a total travel distance from Queenstown to the corner of 1675 miles. From previous voyages of Olympic over the exact same route of travel in 1911, the travel distance from Queenstown to the corner point ranged from 1674 to 1677 miles. So we see that 1675 miles fits right in with that narrow range.) Also, Lowe used the wrong time when he did that little speed calculation for Sen. Smith. According to both Pitman and Boxhall, the ship turned the corner at 5:50pm, not 6pm. A run of 42 miles every two hours by patent log between noon and 6pm is totally inconsistent with making 45 miles by patent log every two hours that was observed between 8 and 10pm that night unless the revolutions had changed, which we were told did not happen.

The only mileages by log that we were told about is 45 miles by log from 8 to 10pm, and 260 miles by log from noon to the time of collision. Now let me ask, is a run of 45 miles in two hours consistent with a run of 260 miles in 11h 40m, or is it consistent with a run of 260 miles in 12h 04m? The first, 11h 40m, gives a 2-hour average of 44.6 miles; while the second, 12h 04m, gives a 2-hour average of 43.1 miles. For me, the answer is very simple.

As for the Gulf Stream, that I will save for another time.
 
Nov 26, 2016
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Hello Sam,

Nowhere did Lowe say that he got that distance by taking the log. He did say that they could use the log to check the speed of the ship.
What he did say was: "I used the speed for the position at 8 o'clock, and got it by dividing the distance from noon to the corner by the time that had elapsed from noon until the time we were at the corner."


Indeed Lowe's testimony looks some how contradictionary. But after long consideration I found a way to make it fit.
The statement "I used the speed for the position at 8 o'clock, and got it by dividing the distance from noon to the corner by the time that had elapsed from noon until the time we were at the corner." puzzeled me for a many years. Where did he know from that they were at the corner at 6 pm?
He cannot simply assume a time and then calculate the speed from it and claim this is accurate.
The statement "we had the log" appears just offhand in the discussion with senator Smith, therefore I never took notice of that before Jim put my nose upon.
Lowe came on watch a 6 pm. He had to work out the DR position. The log was read at 6 pm and indicated 126 miles. This happened to be the distance from noon position to the corner.

Now Lowe had two possibilities to work out the DR position:

a) the clumsy one:
Position at 6 pm: corner 42N 47W
distance to be travelled from 6 to 8: 42 miles, right on the track, as there was no way to find where the turn exactly was made.
Result: 4 arc minutes to south, and 42 miles accordingly 57 arc minutes to west, thus the DR position would make 41-56 N and 47-57 W.

b) the accurate one (*)
The log indicated 126 miles at 6 pm, but the turn was made 10 minutes early, 3,5 miles before the corner.
Thus the position for the turn would have been 42-02 N and 46-56 W.
From there we have to proceed now 45.5 miles (42+3.5) on the 265-course, again 4 arc minutes to south and 45.5 miles accordingly 1°01 to west
and we find ourselfs located on 41-58 N and 47-57 W.

Now lets compare these two:
the clumsy version: 41-56 N and 47-57 W
the elaborated one: 41-58 N and 47-57 W

I should say, for DR position both are satisfactory.
Just the way as Lowe explained to Senator Smith is somewhat skin-deep or uncouth.
I have the impression he was not keen on detailed explanations as Senator Smith would not have understood anyway.

I have much more to say, but will continue in another mail.

Kind regards
Markus

(*) this remembers me somehow on Captain Queek in "The Caine's Mutiny" speeking to his officers:
You have four ways to do your work, the right way, the wrong way, the naval way and my way.
Do it my way and you will get along!
 

Jim Currie

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Hello Sam.

You wrote:

What he did say was: "I used the speed for the position at 8 o'clock, and got it by dividing the distance from noon to the corner by the time that had elapsed from noon until the time we were at the corner." The distance from noon to the corner came from knowing the ship's noontime position and the position of the corner point.
Also, Lowe used the wrong time when he did that little speed calculation for Sen. Smith. According to both Pitman and Boxhall, the ship turned the corner at 5:50pm, not 6pm. A run of 42 miles every two hours by patent log between noon and 6pm is totally inconsistent with making 45 miles by patent log every two hours that was observed between 8 and 10pm that night unless the revolutions had changed, which we were told did not happen.

Yes he did.. and yes he did..., Sam. However, even a First Year Apprentice knows that a ship does not follow a pre-planned course., only a railway locomotive or Tram does that. Lowe was no different. Although he never served as an Apprentice, he was certainly a wee bit advanced from the days when he started to work his way up in the world. Just think carefully about what he was trying to get over the the good Senator.
For a start-off, although he would most certainly have known how far the ship was from The Corner at Noon that day, he could not possibly have known how far Titanic travelled between Noon at 5-50 pm., because he was off watch between 4 pm and 6 pm. Not only that., but neither could his betters have known the answer to that question.
If, however, like his betters, Boxhall, Pitman and Lightoller; 5th Officer Lowe had thought of speed in terms of rpm; then, when he was questioned as to what speed he used to arrive at his 8 pm DR, he would have instantly replied 21-5 knots, sir", not "as a matter of fact it was 20.95 knots."
I'm sure that you are perfectly well aware of the foregoing. Consequently, I can only assume that you have an ulterior motive for avoiding the truth; much in the same way that you are deflecting the question as to why Boxahall made the following statement regarding ship speed...

" I thought the ship was doing 22 knots....Q 15646. Was it an estimate you formed on any materials as to revolutions or as to the patent log?
A: - No, I never depend on the patent log at all. It was an estimate that I had arrived at from the revolutions, although I had had no revolutions that watch; but, taking into consideration that it was smooth water and that there ought to have been a minimum of slip, I allowed 22 knots.


The foregoing evidence begs the question: if the water had not been smooth and there had not been a minimum of slip, what speed would Boxhall have used.? Would it have been 21.5 knots? What do you think his reply should have been?

The only mileages by log that we were told about is 45 miles by log from 8 to 10pm, and 260 miles by log from noon to the time of collision. Now let me ask, is a run of 45 miles in two hours consistent with a run of 260 miles in 11h 40m, or is it consistent with a run of 260 miles in 12h 04m? The first, 11h 40m, gives a 2-hour average of 44.6 miles; while the second, 12h 04m, gives a 2-hour average of 43.1 miles. For me, the answer is very simple."

Forgive me for saying so, Sam but that is a strange question. Very seldom, if ever is the speed of a ship or any other mechanical means of transport consistent over any appreciable length of time.

Marcus quoted the words of Captain Queeg in the excellent story of "The Caine Mutiny". I am reminded of a story I was told as a young lad back in Scotland. It went something like this:

A mother had a son who she adored and in whom she could see no wrong. When her young Adonis reached the age of 18 years old, he joined the famous Scottish Army Regiment of The Argyll & Sutherland Highlanders.
Eventually, after basic training, her son, Callum and his mates took part in a march past in front of the General and their admiring relatives.
First there was a roll on the drums, then the pipes struck-up a blood-stirring Highland marching tune. The Regimental Sergeant Major sucked-in a great breath then yelled..."Byeeee the right, quick march". Young Callum led with his left foot!
Callum's mum was no slouch, she spotted the error right away. Her immediate response was:
"Would ye look at that now, the whole bliddy lot of them are out of step except our Callum".

I rest my case.
 
Nov 26, 2016
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Hello Jim,
your post #87
As for how I know Titanic was to the southward of her course at Noon? I calculated the Great Circle final course for The Corner.
If she had been right on the prescribed line she would have been on a course of 236.5 True. In fact, she was on 241.5->240.5 True.
Therefore, when they found the solar Noon position for April 14, they had to alter course 4 degrees to the right and aim directly at The Corner.


I calculated the Great Circle as well many years ago.
I divided it into three rhomb lines, 540 miles each, thus they add up to 1620 miles.
The courses of the three rhomb lines are: 259.1; 249; 240.5;
The course of the third line happens to be exactly the same as given by Lowe.
(Lowe gave 33 seconds of arc more. I am wondering how he was able to get that?)
This gave me good confidence that i really got the Great Circle approximation by rhomb lines right.

The positions in my model are:
Fastnet: 51-22 N 9-36 W
1st intermediate point: 49-40 N 23-30 W
2nd intermediate point: 46-26 N 36-4 W
Corner: 42 N 47 W

Now my question: How did you achieve 236.5 for the last line?
Even if I split it into four segments I get 239.7 for the last one. The length overall decreases from 1620.3 to 1619.3 miles.
 

Jim Currie

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Funchal. Madeira
Hello Marcus.

Memory's a bit dim now and have lost my notes. However, I worked the problem in exactly the same way as the officers of Titanic would have done.
The course they used was laid down for them. However, If they had had to work the entire Great Circle Course. they would have split it into 10 degree rumb line segments so as to facilitate the use of the Traverse Tables. Then they would have used the Haversine Tables and the logarthmic functions of angles tables.
They would have used the sine and haversine formulae applied to the spherical triangle APB where P = Pole, A = initial position, B the final position,angle A the initial course and angle B the final course. The distance being side AB.

Distance: Hav. BA = Hav P. sin PB+ hav(AB diff PB).

Initial Hav A= hav PB minus ha.v(AB diff AP divided by sin AB,sin AP.

Final Course: Hav. B = hav PA minus hav.(BA diff BP) divided by sin BA, BP...

Note: Hav, = natural haversine and hav = log haversine. sin - log sine of the angle.

As a matter of fact, my distance works out to be exactly 1618 nautical miles. It depends on the departure coordinates used.

Cheers!

Jim.
 
Last edited:
Nov 26, 2016
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Hello Jim,

do we know from somewhere that the great circle from fastnet to Corner was split into 10 rumb line segments?
In the book which i have about astronomical Navigation there is an example for the great circle from Tokyo to San Francisco.
They split it just into three romb lines. The three rumb lines add on to 4491 miles, which is just 31 miles more than the great circle.
When the great circle from fastnet to Corner is split into three Segments, we have 1620 instead of 1618 miles.

There is no need to split into 10 Segments for the benefit of 2 miles. Did WSL split in that way?

Markus
 

Jim Currie

Member
Apr 16, 2008
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Funchal. Madeira
I have no idea, Marcus. I only know that back in the old days, that was the value used in all teaching establishments. the idea then, was to make the GC curve as smooth as possible and to ensure that the Traverse Table values of 600 minutes of D Long were not exceeded.