Icebergs and Field Ice

Mar 22, 2003
5,224
664
273
Chicago, IL, USA
quote:

Had Hichens thrown the helm 'hard over' even 15-30 seconds before the impact, Titanic should have responded almost immediately by heeling into either a wicked starboard or port turn. Such an aggressive turn made at such a fast speed would, in my opinion, have resulted in a pronounced rolling of the vessel which would have been noticed by everyone onboard. This would have been a grabbing on to the wall or railing kind of manuever.
Opinions on what this should have resulted don't count here. What does is available data. That is where trial data comes into play. Forget about Olympic, there was a reference I've seen of a full speed turn done on the Titanic during her trials where it was noted that she took on a slight heel that caused no discomfort. I'm not at home now to dig up where that came from, by I curious enough to see if the heel angle can be estimated from known data that is available. When I get back I'll dig that stuff up.

Trial data can be very useful to test different hypotheses in either an analytical approach or a simulated approach. If you want to use a simulator it best to put in the turning characteristics of the ship you are trying to simulate, some I've said many times before regarding certain simulations done at that MMA.

BTW, I was on the USS Saipan a couple of years ago when she put through a 21 knot hard turn to port as it were. You did not have to grab onto anything.​
 
May 9, 2001
741
2
146
Yes Sam you are 100% correct, opinions don't really count, only data. This is as it should be.

Drawing inference only from the short duty cycle of Titanic's wake as shown in Rev. Brown's pics leads me to think that Titanic was a fairly nimble vessel. Keep in mind that that wake ememates from the back of the ship. Such a short distance of cycle between turns indicates the stern of Titanic was almost 'fish-tailing' to borrow a driving term. Surely the helmsman's arms would be tired after such a series of manuevers. Imagine how quickly the binnacle in the wheelhouse must have been rotating during such a trick. Think on how fast the horizon out ahead of the ship must have appeared to go by from the Captain's point of view.

Some suggest these turns were to calibrate the ship's compass. Possibly. But could it not also be a captain and his senior officers finally seeing what this brand-spanking-new, top of the line, thouroghbred hot rod was truly capable of?? Had her propellers been made of rubber, she would have left three black streaks of smoking water behind her.

Or am I incorrect in that observation?
 
Dec 2, 2000
58,582
373
283
Easley South Carolina
>>Drawing inference only from the short duty cycle of Titanic's wake as shown in Rev. Brown's pics leads me to think that Titanic was a fairly nimble vessel.<<

And a fairly stable one too. The photos I saw didn't show any dramatic heel. I can't say the same for every ship I've been on but then a lot also depended on how fast the ship was going. At minimum steerage way, you really don't notice extreme rudder angles but at really high speeds, I can gaurantee that you will.
 
Dec 4, 2000
3,225
476
213
The model ship used at MMA for simulation does show an outward heel in a hard-over turn, but it would not throw anyone out of bed. On a real ship it would be enough to notice, if you had a mind, but not enough to be uncomfortable.

All of this is at deck level. If you want to experience the fullness of a few degrees of heel, go aloft. The men in the crow's nest--Fleet and Lee on Titanic--would have felt greater movement because of being higher above the transverse rotation point in the hull. Both men reported exactly the opposite to the outward heel of a hard-over left turn ("hard a-starboard" in 1912 convention). They felt the starboard side lift slightly and the nest roll to port. This is in keeping with the starboard side being lifted as the ship rolled over something under water--as Parks and I described in our white paper on the "grounding" of Titanic.

--David G. Brown
 

Derek Gullon

Member
Aug 12, 2006
25
0
71
Not quite sure as to where to post this, and it's slightly off the current topic, if still relevant to the thread.

I have heard a few times of this picture taken the morning after by the chief steward on the Prinz. Does anyone have a digital reproduction of that image.. I'd be most curious to see it.
 

Dennis Evans

Member
Jul 27, 2006
6
0
71
From the information provided here the Titanic requires thousands of feet or less with other combinations of reported evasive manuevers to stop from the reported full throttle speed and factoring in the time delay of the order of commands and engine response then what is the qroup's personal opinion of a likely distance that the iceberg was observed from Titanic and a possible time of observation and collision?
 
Jan 5, 2001
2,299
97
178
Hi Dennis,

quote:

what is the qroup's personal opinion of a likely distance that the iceberg was observed from Titanic and a possible time of observation and collision?
I'm not sure we will get a group consensus...but it would be interesting to hear the range of views, wouldn't it?

Best wishes,

Mark.​
 

Derek Gullon

Member
Aug 12, 2006
25
0
71
Oddly enough I had that same question in my head about 3 days ago. As a result I poked and prodded around some and based on the testimony's and various other sources, the nearest I can figure is this:

From the time lookout Fleet saw the iceberg until 1st/O Murdoch gave the reverse/hard to port order, a delay of approximately 7-10 seconds, (it really depends on whether or not Mr. Murdoch saw the iceberg and gave the command before or after the communication from the nest) that we'll never know, as I'm sure we know the human perception of time is varied on a good day, and this was most certainly NOT a good day.

This being said Q-master Hichens said in the US inq.
"....All went along very well until 20 minutes to 12, when three gongs came from the lookout, and immediately afterwards a report on the telephone, "Iceberg right ahead." The chief officer rushed from the wing to the bridge, or I imagine so, sir. Certainly I am inclosed in the wheelhouse, and I can not see, only my compass. He rushed to the engines. I heard the telegraph bell ring; also give the order "Hard astarboard," with the sixth officer standing by me to see the duty carried out and the quartermaster standing by my left side. Repeated the order, "Hard astarboard. The helm is hard over, sir."

Senator SMITH. Who gave the first order?

Mr. HICHENS. Mr. Murdoch, the first officer, sir; the officer in charge. The sixth officer repeated the order, "The helm is hard astarboard, sir." But, during the time, she was crushing the ice, or we could hear the grinding noise along the ship's bottom. I heard the telegraph ring, sir. The skipper came rushing out of his room - Capt. Smith - and asked, "What is that?" Mr. Murdoch said, "An iceberg." He said, "Close the emergency doors.""

-Extract from the US Senate Inquiry, Day 5 Wed. April 24, 1912

Now this is where things get fuzzier. How long did it take for Capt. Smith to get from his cabin to the bridge?

Having said this nearest I can figure it they had at the most 20 seconds from sighting to impact, at a speed of 21 kts. (avg. speed taking into account what little effect reversing the engines would have had in the time available from the 22.5 kts I understand they were travelling), thats 35.4 ft/sec.. Which translates to at best 700 ft. from the bow to the iceberg.

Please note these are the calculations of an amateur. If anyone has more information I'd love to see it.
 
Jan 5, 2001
2,299
97
178
Hi Derek,

I'm sure others will have a more detailed critique for this debate, but I did want to comment on the issue of the engines:

quote:

at a speed of 21 kts. (avg. speed taking into account what little effect reversing the engines would have had in the time available from the 22.5 kts I understand they were travelling)
I agree that the ship's speed through the water prior to the iceberg sighting would have been around 22.5 knots. Personally, I'd put it slightly higher...perhaps by a few tenths of a knot, but it's hardly a significant difference for the purposes of this debate.

My differing opinion comes in the 'reversing engines' debate. I am aware that Boxhall testified that Murdoch ordered the engines reversed, but Scott and Dillon indicate that a 'stop' order was received prior to the collision. Their testimony has been discussed in detail before on this board so I won't repeat it here. Neither of them testified to the engines being reversed at all before the accident, and I think even if Murdoch *did* order the engines reversed there would have been no time to do anything other than stop them prior to the collision (if that). I did post some Olympic data further up this thread...of course we need to bear in mind that we'll never know the response time of the engineers.

While we can all come to an educated guess as to the time, none of us will be able to come up with a definitive answer...and it's going to be the different viewpoints in this debate that will be most interesting IMHO.

Best wishes,

Mark.​
 

Derek Gullon

Member
Aug 12, 2006
25
0
71
LOL yes.. indubidably, (sorry my son is watching Mary Poppins, <chuckle>) ok then with the new #'s and my theory, ;) 37.9 ft./sec.*20 sec.= 758 ft..

Still not a huge improvement in distance, with an extra kt. and a half of inertial to add to her 'chat' with the 'berg.

umm, ouch? Although the extra speed would have assisted her in the turn. (sideline question; (may have been answered elsewhere) Anyone know what her turning radius would have been at that speed?)
 
Jan 5, 2001
2,299
97
178
Hi Derek,

quote:

Although the extra speed would have assisted her in the turn. (sideline question; (may have been answered elsewhere) Anyone know what her turning radius would have been at that speed?)
As far as I know, Titanic never really exceeded 20 or 21 knots on trials...so I guess the data for 22.5 knots is unknowable.

Best wishes,

Mark.​
 

Derek Gullon

Member
Aug 12, 2006
25
0
71
True Mark, However if the data for speeds to 21 knots is available one can extrapolate the approximate radius at 22.5 kts.

Granted it won't be a hard number, but it could serve to give us an idea of how quickly the bow was moving to port at the time of the collision.

- Derek
 
Jan 5, 2001
2,299
97
178
Hi Derek,

quote:

However if the data for speeds to 21 knots is available one can extrapolate the approximate radius at 22.5 kts.
I agree. Hopefully someone on this board will be able to do so...I'm assuming an increase in speed of 1.5 knots after starting at 21 knots would improve the ship's turning ability more than an increase of 1.5 knots after starting at 10 or 15 knots. In any case, although it wouldn't be definitive, as you rightly indicate it would be an interesting guestimate.

Best wishes,

Mark.​
 
Mar 22, 2003
5,224
664
273
Chicago, IL, USA
Derek:
quote:

Although the extra speed would have assisted her in the turn.
I'm not quite sure what you mean by assisted in the turn? If you are suggesting that the turning radius would be slightly smaller then I have to disagree. In practice, for the majority of hull forms, greater ship speed will reduce response time but increase overshoot. On Titanic the turning circle would have been essentially the same at 11 knots compared to 22 knots, but at the slower speed it would take about twice as long in time to turn the ship a given number of degrees (British Inquiry page 771).

As far the issue of when was the iceberg first observed, that is difficult to answer because we don't know how long it took Fleet to strike the crows nest bell from the time he first saw the berg. What we do know is that QM Olliver was on the standard compass platform when those 3 bells were struck indicating on object ahead. We also know from Olliver that the ship struck the berg as he was entering the bridge, and as Dave Brown said in another thread, he was able to see the peak of the iceberg pass the bridge wing off the starboard side. It has also been shown by experiment that it takes about 45 seconds to walk from the compass platform to the bridge not counting reaction time spent on the platform. Olliver said he left the platform after first looking up and not seeing anything. (He also would have had two funnels blocking his view of anything directly ahead). So the best I can guess at is about one minute minimum from the striking of 3 bells to the impact. If the ship did not start to go into a turn, then we are taking about 760 yards of forward movement.

It should be pointed out that a ship in a turn slows down because of increased resistance through the water during the turn without any engine order changes. For the Titanic this would have meant a reduction in speed from 22.5 knots to about 17 knots with full rudder applied if the ship were allowed to enter a turn before the collision. The real question is this: 'Was the ship turning at all when it collided with the berg?'​
 

Derek Gullon

Member
Aug 12, 2006
25
0
71
By assisted I mean, assisted with rudder authority. Believe me, as an aviator I am more than aware of the effect of speed on turn radius. ;) ok.. with that resolved I'm somewhat confused as to what you mean by "...the turning circle would have been essentially the same at 11 knots compared to 22 knots,...", unless the term "turning circle" is not what I understand it to be.

The 'rate' of turn might be the same, (i.e. 3 degrees/sec., what we in aviation call a standard rate, or rate 1 turn.)

Example: a cessna 150, (single engine, light trainer) will execute a beautiful rate 1 turn inside a 1 nautical mile. An Airbus 320 however will most likely take the better part of a 5 square miles to accomplish the same rate turn. Note in both scenarios the a/c in question is still changing heading at 3 deg./s.

So extrapolating that to Nautical vessels, I would suspect the same reaction. Therefore, the Titanic (in nominal circumstances) at 22 kts. would take let's say (and realize I have NO idea what the real numbers are here these are just for example) a 1 nm. radius to complete a 180 degree turn, whereas at 11 kts. I would suspect it to take .5 nm. radius to complete the same turn. the time required may in fact be longer at 11 kts. but the RADIUS of turn is smaller.

On the topic of time from sighting to impact if there was 1 min, the distance to the berg on initial sighting was 37.9 ft./s * 60 s.= 2274 ft.. So approx .37 nm.

On the point of ships slowing down in a turn due to resistance, I agree wholeheartedly. As I said, the parallels from ship dynamics to aircraft dynamics are wonderful. My return question is, how long would it take for the Titanic to bleed off the 5.5 kts in that turn. Certainly not instantaneous I would think.
 
May 9, 2001
741
2
146
I've often found that comparing aircraft behavior to that of large ships to be problematic. There's too many different forces at work to make them directly similar. And unless your flying a Rutan Starship, most prop driven birds are being pulled through the air instead of being pushed like vintage age ships were.

Not to say ideas about Titanic's behavior cannot be inspired by the actions or handling of aircraft, but only that aircraft are very, very different from ships and caution must be used when attempting to make fair comparisons between the two.
 
Mar 22, 2003
5,224
664
273
Chicago, IL, USA
Hi Derek: Always good to see a fellow aviator on this site. In this particular case Yuri is quite right. The two are not exactly the same. As you know an airplane turns because it is put into a bank and the component of lift of the banked wings toward the inside of the turn is what actually turns the plane. Most people don't know that the rudder on an airplane is neutralized once the plane put into the bank. It counteracts adverse yaw in setting up the bank, but is not needed while the turn is maintained.

On a ship it is different. The rudder is needed not only to begin the yaw movement but to maintain the drift angle between the ship's heading and its direction of movement. This is exactly equivalent to maintaining a certain angle of attack of the wings on a plane by use of the elevator controls. (We just trim it to get rid of the pressure.) The ship turns because of the hydrodynamic effect of the water flow on the ship's hull pushing it toward the inside of the turn, just like aerodynamic pressure on the wings of an aircraft creates lift for a certain positive angle of attack.

The statement I wrote had to do with turning radius. The final turning radius at higher speeds does not significantly change with speed for a given rudder angle. However, the time to complete a turn does. Thus, if takes 37 seconds to turn 22 degrees at 22 knots, it takes about 74 seconds to turn the same 22 degrees at 11 knots. For the Titanic, the final turning radius was about 1925 ft which was obtained during trials with the ship going at 20.5 knots entering the turn. The drift angle for a ship the size of Titanic would be about 8 degrees in such a turn.

For more in depth information on the science of ship turning characteristics and maneuverability, I recommend: http://web.nps.navy.mil/~me/tsse/TS4001/support/1-11-1.pdf.
 
May 9, 2001
741
2
146
An aside: As a teenager, I loitered freguently at the local general aviation airport. I even had one of my first jobs as a lineman/FBO clerk. At one time I even had my student's certificate but never made it beyond solo flight. I still love flying and hope to someday have the time and resources to go after my private's.
 
May 9, 2001
741
2
146
But is the turning radius constant if the engines are not kept at constant thrust? I think not. The same hydrodynamic effect pushing against the hull acts as a resistance to forward momentum, reducing speed, and reducing turn radius proportionally to forward speed.
Correct?