Boxhall's CQD position

Samuel Halpern

Samuel Halpern

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Very interesting analysis Georges.
 
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Georges Guay

Georges Guay

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Thank you Samuel but honestly, without your book(s) data I would never have been able to expose such an analysis! Thanks to you then … ;)
 
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Georges Guay

Georges Guay

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Smith Calculated Distance Run:

Collision Time:
23:46 LAT = 22:13 NYT
NYT + 05h00 = GMT
22:13 + 05h00 = 03:13 GMT

Time elapsed between 23:46 LAT and 03:13 GMT:
[(24:00 - 23:46) + (03:13)] = 03:27

Running Time between 22:36 and 03:27:
23:46 + 03:27 = 03:41 GMT
[(24:00 - 22:46) + (03:41)] = 05h05

Distance Run:
05h05 x 22 knots = 111.8 nautical miles

True Distance Run:
23:46 – 02h02 = 21:44 NYT
23:46 + 02h58 = 02:44 GMT

Time elapsed between 23:46 LAT and 22:36 GMT:
23:46 + 02h58 = 02:44 GMT
19:38 + 02h58 = 22:36 GMT
(24:00 - 22:36) + 02:44 = 04h08

Distance Run:
04h08 x 22 knots = 90.9 nautical miles

Difference:

Smith; 111.8 calculated miles - 90.9 true miles = 20.9 nautical miles :oops:
 
Alex Clark

Alex Clark

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Robert Duane Ballard, a US Navy officer and professor of oceanography at the University of Rhode Island, discovered in the early morning hours of September 1st,1985, the RMS TITANIC wreck. The most probable position where the liner sank was given as 41°43.5’N / 049°56.8’W. Titanic enthusiasts jumped on the occasion to compare the wreck position against Smith and Boxhall CQD’s. It was found that the former distress position was 20 nautical and the latter 13 miles, both further to the west. Boxhall 41°46’N / 050°14’W CQD is recognized to be the official distress position.

Since 1985, every enthusiast tried to explain how a 13 miles offset could have happened. However, deducing 13 miles offset from the CQD against the Wreck position is at the source an incorrect navigation and shiphandling principle. It is absolutely impossible that at the time of collision, the liner was brought dead stop in split seconds, in still ocean waters and iceberg right by her side so to rest at exact wreck position. At the time of collision, the vessel was further east and south due to set & drift meaning that the erroneous distance was even greater!

Everybody saw in the movie Smith rushing in the navigation bridge. After hearing what Murdoch had to say, he ordered to close the watertight doors and the engines all stop (which was already done in real life), then he ordered finding the carpenter to sound the vessel. There is something missing here; the captain should then have told the mate that he was taking over command. The mate would then have notified him that the engines were ordered all stop, the elm hard over to port, the vessel swinging to starboard and there was nothing in sight.

The captain would then make sure the berg was clear before ordering the elm amidship. Later, we have testimonies that the commodore clutched the engines astern and then ahead followed by stop for good. That was a very audacious for not saying a reckless maneuver to fiddle about the engines after hitting ice in open waters. A damaged or loosen propeller(s) blade(s) could have been propelled against the hull and or a shaft been misaligned making the stern tube via the stuffing box, to both ingress more water. At least, the engine settings were slow and for a short period of time to the extent that the liner drifted mostly dead on her own inertia for a minimum of 15 minutes.

In the very best conditions, a fully standing by engine crew would crash stop the lightship giant in over half a nautical mile while being beaten up by enormous vibrations. That never happened. Titanic colliding at 22½ knots was developing 2 billion ft/lbs kinetic energy! According to Samuel studies, the titan went from 38 ft/s (22½ knots) at elm amidship, to 35 ft/sec (20¾ knots) at elm hard over and then to 34.5 ft/sec (20½ knots) after impact.

In 2013, A New Method for Accurate Prediction of Ship’s Inertial Stopping Distance calculated by the ALE (Arbitrary Lagrangian Eulerian) algorithm was elaborated. When compared with shipbuilders’ experimental basin data, the results calculated by ALE algorithm reach a precision of 98% while the results calculated by Captain Topley empirical formula (1988) reach a relative precision of 90.4%. Here is the formula:

View attachment 48362
SJ = The inertial stopping distance
v1 = The ship’s speed at dead stop or dropping anchor
v0 = The ship’s initial speed at stopping
C = The time halved constant of ship’s speed and can be calculated or interpolated from Table 1.

View attachment 48363
If we use 20½k as v0 for the ship’s speed after impact, 0.2k as v1 for the ship’s speed at dead stop and 9.8 as C interpolated from table 1 for Titanic deadweight, we found that SJ (the inertial stopping distance) equates 4.95 nautical miles.

If we then use Captain Topley empirical formula with the same data to corroborate ALE algorithm, while taking advantage of inserting the time it took for Titanic to stop as witnessed (11:45pm – 12:00pm), we found that SJ equates 5.0 nautical miles within a ¼ of an hour.

View attachment 48364

If we draw the result neatly on a nautical chart, making the vessel turning more rapidly at first to then equilibrate her lateral pressure forces and finally stabilize on a North heading by compass, the distance found from the wreck is 15.8 nautical miles, not the celebrated 13 nautical miles.

View attachment 48365
As I was reading Samuel’s book, I came across and froze to that sentence;
Senator SMITH; Mr. Boxhall, you seem to be the one upon whom we must rely to give the difference between ship's time and New York time; or, rather, to give ship's time and give the New York time when this accident occurred.
Mr. BOXHALL; At 11.46 p.m., ship's time, it was 10.13 Washington time, or New York time.


That very single reply is a very significant and reveling phrase! Like Samuel stated, it certainly played a role in the CQD miscalculations, since at 11.46p.m., ship's time, it was not 10:13pm New York time, but 09:44pm! Let’s see what I come up with…

«At 11.46 p.m., ship's time, it was 10.13 p.m. New York time»

In modern notation, at 23:46 LAT it was 22:13 NYT. Thence, 23:46 LAT – 22:13 NYT = 01h33 time difference between the liner and New York or 03h27 between the liner and Greenwich or 05h00 between New York and Greenwich.

When Boxhall made is famous calculations to deduce the CQD position, he used 23:46 LAT for the collision, 22:36 GMT as noted in his Celestial Navigation Logbook for the evening celestial fix and a speed of 22 knots.

1. Boxhaul Calculated Distance Run:
Collision Time:
23:46 LAT = 22:13 NYT
23:46 LAT – 22:13 NYT = 01h33
05h00 – 01h33 = 03h27 GMT

Running Time between the 22:36 GMT celestial fix and 03:27 GMT collision time:
[(24:00 – 22:36) + (03:27)] = 04h51

Distance Run:
04h51 x 22 knots = 106.7 nautical miles

2. True Distance Run:
23:46 – 02h02 = 21:44 NYT
23:46 + 02h58 = 02:44 GMT

Time elapsed between 23:46 LAT and 22:36 GMT celestial fix:
23:46 + 02h58 = 02:44 GMT
[(24:00 - 22:36) + 02:44] = 04h08

Distance Run:
04h08 x 22 knots = 90.9 nautical miles

Difference:
Boxhall 106.7 miscalculated miles - 90.9 true miles = 15.8 nautical miles

As I said previously; «If we draw the inertia stopping distance on a nautical chart, Boxhall CQD distance found from the wreck is 15.8 nautical miles.». Strange coincidence isn’t it?

Notes:

Astern power equates 40% Ahead power

Thomas P. Dillon;
engines brought to stop 1½ minute after impact
engines stop for ½ minute
engines brought to Slow Astern for 2 minutes
engines stop
engines brought Ahead for 2 minutes
engines Stop for good

Engines brought Ahead for 2 minutes supersedes engines brought Slow Astern for 2 minutes.

Case 2. Frederick Scott:
engines brought to stop 1½ minute after impact
engines brought Astern for 5 minutes
engines Stop
engines brought Slow Ahead for 10 minutes
engines Stop for good

Engines brought Slow Ahead for 10 minutes supersedes engines brought Astern for 5 minutes.

Thence, the liner drifted mostly dead on her own inertia...

Georges, im just getting my head around all the figures, is the suggestion that Boxhall position for the collision was perhaps closer to the mark but that the ship drifted to the wreck position afterwards, hence the seeming inaccuracy in Boxhall’s CQD position?
 
Jim Currie

Jim Currie

Senior Member
There is no evidence to show that a second helm engine order was given as part of the berg avoidance tactic. To be effective such an order would have to have been given immediately. In fact. the helmsman was pointedly asked about that and was very positive in his answer. I quote:

1314. You were given the order to hard-a-starboard? A: - Yes.
1315. Was that the only order you had as to the helm? A: - Yes.

A second helm order was given... but much later... when the iceberg was astern. This second order has been stretched by researchers to include Murdoch's attempt to clear the berg. However, an experienced officer like Murdoch would know that to be effective if at all, it would need to have been given as part of a flowing sequence of events.
 
Brody Tarrant

Brody Tarrant

Member
I remember reading some where that Boxhall asked that his ashes be dumped at 41°46N 50°14W.
 
M

Mark Baber

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Moderator
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25 April 1967: The final survivor from among Titanic's officers, fourth officer Joseph Boxhall, dies in Christchurch, Hampshire, England, at the age of 83. His body will be cremated and his ashes scattered over the site of the sinking. (Sources: Eaton and Haas' Titanic: A Journey Through Time; Encyclopedia Titanica: Fourth Officer Joseph Groves Boxhall,
Joseph Groves Boxhall : Titanic Survivor.)
 
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Vincent Brannigan

Vincent Brannigan

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Astern power equates 40% Ahead power

Im just wondering where you get this

When running ahead at 83 revolutions per minute on her reciprocating engines, the entire power plant would develop about 59,000 horsepower, of which 18,000 horsepower would be contributed by the turbine. (Halpern)
So you shut off the turbine the Triple expansion engines develop 41000 HP
Titanic sea trials ""crash stop" was performed in which the engines were reversed full ahead to full astern, bringing her to a stop in 850 yards (780 m) or 3 minutes and 15 seconds."
So there was enough power to stop her in half a mile at 20 .5 knots including "reversal tiime" (but probably not response time )
.
For reversal time
With engineers at the ready, it would take from 10 to 20 seconds to get the engines to start backing and about 50 to 60 seconds for them to start backing hard. (SAM)

So its 60 second or more for full power and then stopped in 140 more seconds How does the square with 40 % power?
 
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Georges Guay

Georges Guay

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x


Im just wondering where you get this

When running ahead at 83 revolutions per minute on her reciprocating engines, the entire power plant would develop about 59,000 horsepower, of which 18,000 horsepower would be contributed by the turbine. (Halpern)
So you shut off the turbine the Triple expansion engines develop 41000 HP
Titanic sea trials ""crash stop" was performed in which the engines were reversed full ahead to full astern, bringing her to a stop in 850 yards (780 m) or 3 minutes and 15 seconds."
So there was enough power to stop her in half a mile at 20 .5 knots including "reversal tiime" (but probably not response time )
.
For reversal time
With engineers at the ready, it would take from 10 to 20 seconds to get the engines to start backing and about 50 to 60 seconds for them to start backing hard. (SAM)

So its 60 second or more for full power and then stopped in 140 more seconds How does the square with 40 % power?

I am also wondering where you get this; «So there was enough power to stop her in half a mile at 20.5 knots...»

Here is the testimony of Edward Wilding, Harland & Wolff naval architect, at the British enquiry;

25295. The trials that I have were made again off Belfast Lough. Both engines were running at about 60 revolutions, corresponding to a speed of about 18 knots. The helm was left amidships and both engines were reversed. The way was off the ship in about 3 minutes and 15 seconds from the order to reverse engines being given, and the distance run was just over 3,000 feet. I might mention in that connection that, so far as we on the bridge could see, the engines were not reversed as quickly as we had seen them, and the distance is probably a little on the large side; but that is what we actually observed, and it would be very difficult to put an estimated correction on it.

Both (reciprocating) engines running at about 60 revolutions,
- noting that the architect made no mention of the turbine, neither of its revolutions
Corresponding to a speed of about 18 knots,
The way off the ship took about three 3 minutes and 15 seconds from the order to reverse the engines
The crash stop distance run was just over 3,000 feet,
So far as we could observe on the bridge, the engines were not reversed as quickly as we had previously seen them,
- interesting to note that the time needed to reverse the reciprocating engines varies depending on which chief or senior engineer was in charge at the maneuvering stand and its tolerance to risks;

- Carefully engineers waited for clutching the linkage until the engine had stopped,
- Experienced engineers would throw the linkage when the engine was doing just a few remaining rounds,
- High skilled engineers would switch the engine astern at the most possible remaining round,
- Brutal engineers would just throw the linkage over, regardless of mechanical overloads or material frontiers!

The Senior 2nd Engineer in charge of the engines, John Henry Hesketh, as well as the Assistant 2nd Engineer in charge of the boilers, Johnathan Shepherd, were both all way up in front of BR6 at the time of the collision (SH). Consequently it took about a minute and a half just to stop the engines, while the berg was already 2 ships length astern. That’s the consequence of steaming at Sea Speed toward a known arctic field ice without an Engine Room ringed to Standby.

60 Revs / 18 knots / 3 minutes and 15 seconds / distance just over 3,000 feet

If I use Samuel’s formula from Speed vs. Revolutions paper, at 60 revs the crash stop speed was certainly not 20½ knots, maybe not even 18 knots, but possibly closer to 16 knots if not less.

Speed vs. revolutions formula when the central propeller was engaged (V1);

V1 = 0.563 R^0.8472 for Revs ≥ 50 rpm turbine engaged

Let’s see the result if we use 60 revs;

V1 = 0.563 R^0.8472
V1 = 0.563 x 60^0.8472
V1 = 18.1 knots or the same result as the naval architect.

Now, let’s see Titanic speed prior the Crash Stop test if the central propeller was disengaged and only «both engines running at about 60 revolutions» as mentioned by the architect

Speed vs. revolutions formulas when the central turbine was disengaged (V2);


V2 = 0.488R^0.8472
V2 = 0.488 x 60^0.8472
V2 = 15.7 knots

or

V2 = 0.65^1/3 V1
V2 = 0.65^1/3 x 18.1
V2 = 15.7 knots

or

V2 = 0.866 V1
V2 = 0.866 x 18.1
V2 = 15.7 knots

The Marine Casualties Investigative Report of the cruise ship COSTA CONCORDIA

2) Speed of the ship was not decreased but remained between 15 and 16 knots, even beyond the point of turn planned but not respected at a speed of 16 knots, the ship as shown in by "manoeuvring booklet" (Annex 31), required 1299 meters (0.7 miles) in order to stop his momentum. The ship was found that speed bow to the ground at a distance from the coast than half a mile, as shown by the tracks AIS / VDR (the distance of half a mile to sixteen nodes is covered in about 2 minutes).

At 18 knots, Titanic needed 3,000 feet to stop while Costa Concordia similar in displacement but equipped with state of the art propellers in line with twin diesel electric twice as powerful, needed 4,000 feet to stop from 16 knots! There is something that doesn’t add up here, even if Titanic was making 16 knots!

Astern power equates 40% Ahead power

Why Full Astern Power is usually less than Full Ahead Power?

- The propeller blade section is designed for maximum efficiency in ahead thrust,
- In astern direction, angle of attack is high on back of the blade,
- The propeller will absorb very little available power due to severe eddying and cavitations occurring on the face. Therefore, efficiency is very low.

Blade Face and Back

The face of a blade is considered to be the high-pressure side, or pressure face of the blade. This is the side that faces aft (backwards) and pushes the water when the vessel is in forward motion. As the propeller blade cross section is similar to an airfoil, the back of the blade is the low pressure side or the suction face of the blade. This is the side that faces upstream or towards the front of the vessel. When going astern, the convex face becomes the high-pressure side while the concave blade becomes the suction face. The propeller efficiency is therefore severely disrupted.

A vessel going from Dead Stop to Full Ahead 16 knots will take on average half the distance to go from 16 knots to Dead Stop. That’s what I consider to be the lost in power efficiency of 50% when gong astern. Back then in 1912, I would tend to be generous by saying that the lost of propeller efficiency was closer to 40% than 50%. That’s what I meant by Astern power equates 40% Ahead power. It as noting to do with the engine power but rather that the propeller blade section is designed for maximum efficiency in ahead thrust and loose considerable thrust in the astern direction.

Therefore,

Engines brought Ahead for 2 minutes supersedes engines brought Slow Astern for 2 minutes.
Engines brought Slow Ahead for 10 minutes supersedes engines brought Astern for 5 minutes.

Thence, after the helm was ordered back amidships after the Hard-a-Port stern avoidance maneuver, the liner drifted mostly dead on her own inertia toward the North magnetic and for a distance up to 5 nautical miles, to finally make her red sidelight be visible by naked eyes to Californian...
 
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